Author: David de Regt

After over a year with the power system, and several tweaks, I’m at the point that I’m very happy with where things have landed, and figured it was time for an update. I also convinced a buddy boat of ours, Inquest, to do the same system, and we’ve been iterating with each other for the last year, which continues to be helpful. The original post from last year has more details on some of the history on why I went in this direction, if you’re interested, but this post will be self-contained about the current system if you just want to know where we landed and the benefits.

Why 48V?

Let’s get the basic question out of the way — why the heck did I go with 48V? Most boats are 12V, with some natively 24V, but no one is doing 48V.

So, I don’t just hate myself. I mean, obviously there’s a little of that, but there are some tremendous advantages. If you look at off-grid systems for homes, they’re all 48V, and my target was a lot closer to an off-grid home than a traditional “boat”. And a lot of that is because converting back and forth between 48VDC and 120VAC is more efficient than to/from 12VDC. Similarly, for MPPT conversion off solar, downconverting to 48V is more efficient than all the way down to 12V. But even moreso, at house-level loads (i.e. regularly dipping into multiple kilowatts), the sizes of cables that you need to run to safely transfer power to/from 12V batteries is some combination of absurd, heavy, and somewhat dangerous.

Running 5kVA inverters with 12V batteries, we would need to run four 4/0 cables each for the positive and negative terminals (and, realistically, to be safe, another set of four for the ground), to each inverter — they need around 1000 amps! With 48V batteries, we only need to run one each. Simpler, cheaper, far less inflexible cable to run around the boat, and generates much less heat at the terminals from 1/4 the amp load. I only have to run 4AWG wires from each battery to a common terminal, because 100 amps is more than they will ever see.

Finally, because of the low amp loads, battery chargers are simpler, cheaper, and more efficient. The same Quattro in 48V that charges at 70A will only do 120A at 24V or 200A at 12V (28% less power). Where I would need multiple MPPT chargers for my solar bank, I can instead use a single not-horribly-expensive one. Basically, everything in the 48V world is smaller, lighter, cheaper, and more efficient.

The downside to 48V, of course, is that you now need some way to feed your native 12V loads, but that turns out to not be too bad of a problem to solve, as I’ll discuss later. That said, many devices are coming natively in 48V these days — we have a native 48V windlass that plugs right into the house bank, POE networking gear uses 48V, there’s a new generation of thrusters out that use 48V, and even watermakers are starting to come out in 48V. So it’s becoming more standard in the marine world, but I would say it’s still in the “bleeding edge” territory for most things.

Batteries

The core of the system is a 600Ah 48V house bank, made of six 100Ah BestGo packs in parallel. I picked these packs because they, at least at the time, were the best value in US-company-warranty-backed Lithium packs available (the 6 batteries were around 11k$ shipped to my door). They’re also IP66-rated, which, on a boat, in a cabinet right under the A/C drip tray, next to a washer/dryer unit, and with the A/C water lines running literally right over them, seemed like a good idea. Lastly, Will Prowse did a teardown on them and found the build quality to be unmatched in their price range. They’ve been working flawlessly for me, with very little temperature buildup even under heavy charging and discharging.

The batteries form the core power storage for the system, which is then mostly transformed to the other working voltages around the boat (12V and 120/240VAC), though more and more native 48V equipment is coming available. I’ve converted to a larger 48V windlass which pulls directly off the batteries and I’m running Starlink directly off POE from the batteries.

You can read about lithium batteries and what a different world they are than any sort of lead-based batteries, but you really have to live with them daily to appreciate how amazing they are. There’s no memory, so you don’t have to worry about equalizing or seeing your capacity dwindle every day since you last equalized. You can happily draw them down to 20% or lower and still get thousands of charge cycles out of them. You can pull huge loads off them and the voltage sags by a couple percent, not 10-20%. You just treat them like a big dumb bucket of power — you charge up by filling the bucket, you use it by taking power out of the bucket — and there’s nothing else to think about. It’s just that easy. We will never go back to lead after living with lithium for a year.

Inverters

One of the goals of my system was to run 100% of AC loads through the inverters, and hence have no difference in anything on the boat between running off batteries and off shore power or the generator. I wanted to build the system to just leave the inverters on 100% of the time and not have to care. Leave the water heater on full time, it’ll be fine, and you can shower whenever you want and not have to think about it, basically like you’re living in a house.

And it’s worked — every night, Hannah and I charge our phones off outlets with integrated USB ports that are powered off the inverter, because it’s easy and the tiny efficiency gains by going directly to DC don’t matter to us anymore.

I went with two of the Victron Quattro 48/5000/70 units. The Quattros have several neat features for us:

• Auto switching between shore power and a generator, with different input power limits for each.
• Supports constant draws of 4kw each, and burst up to 8kw for a brief period of time, like for A/C compressor startup.
• Charges at up to 70A each (though with the 4kw limit, this tends to actually be more like 60A, in our experience).
• PowerAssist — if you’re on shore power/generator, and you need to pull more power than the input power gives you, it will simply augment the extra load from the batteries. When we’ve been stuck in situations with only a single 15A 120V outlet available on a long extension cord, PowerAssist has been awesome — run the A/C for a while, batteries slowly drop, turn it off, batteries charge back up.
• Handles split phase power, even when we’re plugged into single phase power — one inverter charges and the other inverts, but the boat still has 240VAC available.

I was thinking there would be a lot of nuance to getting this system to work correctly in a wide variety of circumstances, but there was actually only one semi-hidden thing I had to figure out. You really need to fire up their ancient Windows-based administration software and specifically change the two inverters to disable “Switch as Group” — this means that, if one leg has power and the other doesn’t, or if the second leg isn’t actually split phase (i.e. run in parallel with the first leg due to lazy marina electricians), the first inverter will still switch to using that external power, but the second one will stay as an inverter, providing that second leg of phased power for the boat. We have used this feature dozens of times at this point in the last year and a half, and it really is what makes the system set-it-and-forget-it under virtually all possible shore power electrical wackiness.

12V System

This area has undergone the most iterations since getting this boat. My original system was basically using the Port start battery as a “12V house”, and using DC-DC converters to keep it charged/fed, with the converters feeding all but burst-overloads (i.e. dinghy lift, windlass, etc.) However, this system had two primary categories of downsides:

1. Your “house” is your start battery — if something goes wrong with the dc-dc converter, you’re rapidly going to nuke your start battery. There was an ACR that would keep the other start battery isolated, but still, one of your motors would be dead for a while until you got enough stuff safely running to nurse it back to life.
2. When you crank the motors or otherwise pull high current (windlass, etc.), the lights in the boat dim, some sensitive devices reset, etc. The DC-DC converters don’t keep up with engine cranking, so the voltage sags down to ~11V, which isn’t enough for many devices. I kept having to put small buck-boost converters on sensitive electronics like the router and the N2k network to keep them from dropping out every time I fired up in the morning.

I ended up wanting to move to a completely isolated 12V house setup that had nothing to do with the start batteries, and, ideally, was not, itself, battery-backed at all. I spent too much money on a 3000W 48->12V converter from Zahn, but after a couple weeks of being frustrated at how it did not respond well to transients (flushing a toilet made all the lights in the boat dim), we dinghied back to the boat one afternoon to find the entire 12V system dead with the Zahn board having completely died.

I returned the Zahn and decided to go with the tried-and-true-and-cheap Orion-Tr converters, and am now using three in parallel. That gives 90A of continuous and up to 120A of burst capacity, which is more than if we had every house-DC device on the boat turned on at the same time, and a bunch of redundancy (2 of them can die and we can still survive on a single 30A Orion-Tr). I have a backup switch to link the 12V house back to the port start battery if I need to, for some reason, which is also very helpful — if something goes wrong in either direction, I have another 12V system waiting. It also means I can do maintenance on aspects of the power system without actually having to turn the lights off, which has come in handy a few times.

Charging from the Alternators

One of the weak points of the original power system was charging the 48V house system off the alternators. My engines don’t have any sort of kit available to mount a second 48V alternator on them, and there’s not really a good place for one to hack one in, so I’ve given up on that route and am sticking with 12V alternators so that the motor systems are still self-contained for safety/redundancy.

So, with 12V being where I was stuck, the factory “80A” (I never saw them able to put anywhere near that amount of current) alternators weren’t gonna cut it. For the port side, I ended upgrading to a Balmar 94LY 210A alternator, which required a little custom hacking on the alternator bracket to make it fit, but ended up nestling in there just fine with the factory belts.

So, now I have the ability to generate something north of 200A while under way. But how can I utilize that when it’s at 12V and my batteries are at 48V, and how can I make sure it only tries to pull that charging current when there’s actually alternators providing that current, and not just drain the battery down?

I originally got in on an early alpha test of the upcoming WakeSpeed WS3000 bidirectional DC-DC converter, which was something that you would plug between your 12V start battery and your 48V house battery. When the 12V system was charging, it would pull current from the low side and send it to the high side to charge the house batteries. Then, when the motors were off, it would send power from the 48V high side to the low side to trickle charge any of your 12V loads (or, in my original case, “my entire 12V house load”).

To control the alternator itself, I first tried using a WakeSpeed WS100, a simple 3-stage charger. However, we quickly found that, the way the WS3000 was working, it was basically fighting with the charging algorithm of the WS100 and confusing the hell out of it, since it wasn’t responding like a battery would. I ended up converting to using a stupid-simple automotive adjustable-fixed-voltage regulator, which worked great for a while and I just locked to outputting 14.5V. After several months, though, that unit just magically stopped working and I switched to a Balmar BRS-2T, which is just a beefier adjustable-fixed-voltage regulator, and that’s been solid ever since.

Unfortunately, after working extensively with Wakespeed for around 9 months to tweak the WS3000, we both came to the conclusion that the way they were approaching the charging algorithm needed some fundamental reworking. They were more focused on other product areas, as a tiny company, so they had to put the project on ice for a while and come back to it at some point, but it had left me without a particularly usable solution here.

I ended up buying a Calex 3000W Bidirectional DC-DC converter board as a bit of a hail Mary and built some software to control it with a Raspberry Pi. I was thinking that a basic PID control loop would work really well to have the unit basically self-report how much current you could pull off it — if voltage dropped below X, pull less current; if voltage goes above X, pull more current; and just keep continuously tuning. Turns out, this idea actually worked unbelievably well. The very first outing, I watched the telemetry with joy as we started out idling and watched the converter fill in the current that the diesel preheaters were using. Then as we added RPMs, the motors heated up, and the preheaters turned off, it switched to charging the high side and the current quickly jumped up and found its happy place all on its own, every time we changed RPMs.

At this point, when at hull speed, I can safely pull ~180-190A from the 12V side to charge the high side at around 45A, for hours on end. When we’re on plane at higher RPMs, I easily cap out the 3000W converter around 225A of low side draw. It’s fully automatic, and just works, running in the background, doing its thing.

It’s really a game-changer for us — when we’re moving every day, we can usually get pretty close to fully charged with every trip, combined with solar. We’ve put very few hours on the generator since getting this system tuned around late June, despite spending almost two full months without plugging into shore power in Maine this summer. Inquest also installed this same system and has been beta-testing the BoatKit setup and has ended up in the same place — very little generator running required anymore.

Solar

The boat originally came with four older rigid solar panels that were nominally rated at around 200W each. That just wasn’t gonna cut it — we go through a lot of power. Also, the rigid solar panels are heavy.

I’d had very good experience in the past with flexible solar panels and using Eternabond tape to hold them down to fiberglass — the panels on our last boat survived a (non-direct-hit) hurricane just fine, and installation becomes non-permanent and super-easy. After measuring really carefully and deciding how much to work around the radar tower and FLIR on the front, I settled on putting 15 of the SunPower 170W flexible panels up top, for a nominal power capacity of 2550W. To help with shading issues, I connected them up in five parallel groups of three panels. This put the panel voltage at around 90V, with a peak current of around 28A. Better still, the total weight of the 15 flexible panels, including installation tape, is still less than the 4 rigid panels they replaced.

Getting the wiring routed semi-cleanly was not a fun endeavor, but in the end it looks pretty decent, and no one can see it from below anyway! It’s all running through a single Victron 150/70A MPPT charge controller, which seems to be doing a great job, after replacing an initial buggy one with an RMA’d one that’s now fine.

As you can see, solar is covering a significant portion of our usage. We basically only went significantly over on hot days when we had A/C on or overcast days where solar was bad. But even with running A/C regularly (it was a hot summer, even in Maine!) and all the other crazy things we do, we only averaged around an hour a day of generator usage (usually 2 hours every other day). So, the solar system is a complete success.

Generator

The boat came with a Northern Lights 12kW generator, configured to output two phases of up to 50A of 120V. It’s a simple but known-to-be-reliable generator with fully analog controls and simple maintenance. This is actually a pretty perfect setup for the boat, because it matches the shore power input size (50A/240), and the two inverters want to pull around 8kW from it when charging the batteries. Running a diesel at high load is much more efficient than running at low load, so in our setup, we only run the generator when we need to charge the batteries, not just to run loads.

To keep us from having to think about generator timing, for the most part, I’ve set up a full autostart/stop system. Since the generator is fully manual/analog, I had to install a DynaGen TG410, which can be configured to take a single input line of high/low voltage and trigger a start/stop of the generator. It runs the preheater for a set interval, cranks, checks for voltage, etc. — it’s a full generator controller, basically.

I then configured our Victron Cerbo GX’s generator start/stop module with simple simple parameters — fire up when we go below 40% SOC, stop at 85%, and during quiet hours (middle of the night) only start in an “emergency” of 20% SOC. With this setup, we basically don’t have to think about charging. If it gets lowish at any point, the generator charges back up. Or we can easily manually trigger timed generator runs if we want to take control of the situation. Super helpful.

Monitoring

One of the key reasons my cabinet looks like a Victron ad is because of how nicely the whole system plays nicely together to tie into the Cerbo GX. It’s a cheap box you add onto your Victron setup that you can plug a little touchscreen (Touch 50) into for your power panel, and it displays all kinds of neat info, also allowing you to control important aspects of the system. But it also connects to your boat’s internet and can stream your data to the VRM online system for monitoring reasons (it can email you with issues) and digging into data in more detail.

After over a year of having this system, the sheer novelty of the monitoring system has worn off, but it is still incredibly useful. Especially after installing a third party modpack called GuiMods, you can fit a pretty crazy amount of critical data on one screen. We have detailed info about the shore power and usage, what the inverters are doing, AC and DC loads at present, state of the batteries, the solar array, our pile of temperature sensors around the boat, and our tank levels.

The Cerbo is really what seals the deal on the Victron suite, at least for me. The rest of the equipment also appears to be top-tier, but the Cerbo tying it all together is some sweet icing on the cake.

Summary

The system is really honed-in at this point. We can plug into any power source from 15A/120V to 50A/120-240V and the system just works. Speaking of plugging in, unless you already have a motorized shore power cord setup, just go get a SmartPlug. It’s just worlds better and safer, in every way. Stop delaying or saying it’s not that important. It is. Just do it.

We very rarely have to pay attention to power in the slightest unless we want to run A/C for a while, at which point we usually want to plan a generator session to make sure we start the night with pretty-full batteries to make sure we can keep the A/C on for the whole night and still be fine in the morning. Power stats are a fun thing to watch, rather than something to be carefully managed. There’s always hot water and ice in the icemaker, the TV can go on whenever, and I play computer games on a desktop computer with a giant monitor all night.

The system’s mature form is now designed around redundancy, with many different ways to do everything from charging the 48V batteries to powering the 12V house system to starting the engines or generator. It’s being run full time on two boats that are both techy liveaboards that spend more time at anchor than in marinas.

Hopefully sometime in the next year I’ll be able to get the BoatKit stuff out to the wider world so this last piece of the 48V puzzle can be accessible to the masses. But even without that piece that ties the 48V system to the motors, the rest of this setup is still something to consider if you’re looking at rebuilding your power system. Hit us up with any questions!

Note: This post has been superceded by an extensive newer post going into the details as the system has evolved over time.

Around the time we decided to buy the Endeavour, I had come around to the idea that, if we instead committed to sticking with our old boat, I was going to have to redo batteries to non-lead-based technology of some sort. I was tired of always running out of power, managing/timing generator runs, carefully running as absolutely little as possible, timing showers to after we made a travel hop, etc. and wanted a change for our next year+ of east coast cruising.

When we looked over this Endeavour, in the electronics cabinet I found mostly original equipment with a few awkward slightly newer pieces thrown in. I quickly came to the conclusion that, if we bought it, it was a good excuse to do a complete writeoff of what it came with, and go nuts with something I’d be really happy with for years.

A couple weeks before we looked at the Endeavour, Kevin @ Airship posted a fantastic blog post talking about their power system. They’d been working on it over the last year, and were finally pretty happy with it. They had decided to do what most boaters consider pretty crazy — run 100% of their AC power through inverters. I’d been contemplating a system like that for a while but it seemed like absolutely no one did it, so it had been simmering on my back burner throughout 2020. However, when this article came out, it validated all of my beliefs about a modern power system for uses like ours:

• Lithium really does live up to the hype in liveaboard boating usage
• Heavily load your generator if you’re going to bother starting it — running a 9-12kW generator and pulling 1kW slowly charging batteries is inefficient and bad for your generator
• Run everything through inverters and use power boost as needed if shore power isn’t enough
• Get to a place where you barely have to think about power on the boat anymore

Throughout 2020, every day we weren’t plugged in at a marina, power was a foremost concern and dictated much of our scheduling. When are we going to generate so we can time our showers around the limited duration hot water? Are there people around us? Crap it’s 8pm we should probably not generate at this point, but our batteries are getting lowish so we have to either go to bed early or just read books or whatever to avoid using too much power overnight and drawing the batteries down too low.

Early in the trip, the mental load of managing all this was a little fun, even though we were already used to it from before we came out east. To semi-quote JFK, we don’t do these things because they’re easy, we do them because they are hard. But at some point it’s basically just an algorithm and it gets old to manage. So I decided I was done with it.

Victron Quattros

The Slowboat article led me to a newer suite of products from Victron called the Quattros that are a bit of a godsend for this sort of marine off-grid system. These actually go above and beyond the standard age-old inverter/charger combo unit. There’s two AC inputs, so you can put your generator in one, fix the current limit (50A for us), and then plug the second one to shore power, and, from a monitoring panel, easily update the current limit depending on whether you plug into 50, 30, or even 20A at a marina. Then it would use whatever power source was available as input.

Our boat has one 230VAC device currently: the older watermaker that came with it. While I may replace it someday, I wanted to make sure that we could support it, so I needed to keep the full split-phase system that the boat came with. I also figured I’d probably upgrade the heating/cooling to a chiller system that would much rather be on 230VAC than 120VAC. While there’s a few options for accomplishing this, I decided to go with using two slightly smaller Quattros (5KVA) in a split-phase configuration, so that if one of them broke, I’d be able to quickly rewire/reconfigure the system to still function off the one remaining unit until we could get a replacement.

The Quattro has a bunch of neat features, not least of which is the PowerAssist functionality, which is part of what really sold me on the system. If you’re plugged into shore power of a certain amperage, and your panel needs to draw more power than the shore power can provide, the Quattro will fill in current from the batteries. So if you’re in a smaller marina with single-phase 30 amp, you can run the microwave for a while or the air conditioning, and it will fill in any extra power requirements over the limit. Then, whenever you drop below 30 amps again, it’ll go back to charging the batteries up with whatever spare current is left. This is really useful for marine air conditioning units, which traditionally require huge loads at startup (30-40 amps) for a few seconds, which tends to blow breakers, but this system totally avoids that problem.

So pretty early on, I decided to pick up a couple Quattros, and was able to move on to figuring out what to do for batteries. The first step down the carefree-power path I’m heading down is getting a silly amount of battery capacity, so this was going to likely be the most expensive part of the new setup, and hence required a ton of research.

Why Lead Batteries Are Terrible

Lead batteries have a bunch of nasty characteristics for long-term usage. When you start at 100% charge, you can only really bring them down to around 50% before you risk dangerously shortening their life span. So you start charging there. Then, once they get back up to ~80% charge state, they start increasing internal resistance and accepting charge slower and slower. Traditional logic is that to get from 85% to 100% takes ~3-4 hours for lead acid batteries. So you just don’t do it if you’re at anchor. You cycle between ~50% and ~85%. We had our auto-generator-management on the Meridian to cycle from 55-85%. So if you have, say, 1000 Ah of capacity, you get to use ~300 Ah of it from your main cycle. Not a great return.

But wait, it gets worse. The chemistry of the anodes in lead batteries is such that, when you run them down, on the exposed areas (where the electrolyte goes down), they get a little lead sulfate coating that you need higher voltage to get through. And you only uncover that surface up to the % that you charge back up to. So when you cycle up to 85% and then back down again, 15% of the anode starts building an ever-thicker coating on it and starts to crystallize. The next time you charge back up, to get back to 85%, it takes even more time than last time. By the time you cycle 50-85% ~4-5 times, you’ve lost 10% or more of your battery capacity, and you’re actually cycling between 50 and 75% — now you get 200-250 Ah of your 1000Ah bank to avoid damaging your batteries.

The only way to restore that capacity is to get back to 100% with a really long generator run as soon as possible, and every few weeks you need to run an “equalize” cycle that runs very high voltage through the batteries to “break through” that crusty shell on the anode and get your lost capacity back. It’s a pretty terrible system, all in all. And so not only are you constantly just managing these tiny-range % cycles on your batteries, you’re also managing plating that you need to work these really-long generator cycles in to break through, and every few weeks get a full ~8-10 hour generator run (or be in a marina) in place to do an equalize cycle.

Even being “nice” to your batteries and following things by the book, even “good” AGM lead batteries only get around 500 cycles down to 50% before they’re at a fraction of their initial capacity. So, doing 1-2 cycles a day, we basically had a year or so before we were working with a pittance of capacity. After a year of this game, and changing out the batteries once already, I was pretty tired of it and ready for a change.

I spent some time looking into Firefly (carbon foam-based) batteries and a couple other intermediate chemistries, but very quickly settled on a much better option.

Lithium Batteries

Lithium, specifically LiFePO4 chemistry, is in a category of its own in the battery world. These batteries can be around 1/4 the weight of traditional lead-acid batteries (either FLA or AGM) for the same capacity, and around half of even a carbon foam-based setup. So on things like boats, where weight is the devil, if you want a ton of capacity, you go Lithium, or you end up putting a thousand pounds of lead somewhere on the boat. The weight consideration is a nice boost in and of itself, but the biggest wins with Lithium are actually in usable power.

Remember my rant above about the fun 55-85% cycles on AGM and how you can’t get back to 100% without a ton of time, and the memory effects you need to counter? Yeah, those are gone with Lithium. You can safely draw them down to 20% and charge right back up to 100% and get 2000-3000 of these 80%-capacity cycles out of them. If you only draw down to 50%, you get 5000 or more. Better yet, that 20-to-100% cycle is at full speed the whole way. The batteries accept an essentially full rate of current from the bottom of the barrel right up to the last topoff. So you can really just use them as a reservoir like a fresh water tank — top off when it’s easy, let it live low if you want to and understand the risks, and add a little bit if you want here and there.

To do a little math here, the Endeavour came with 800Ah of AGM. With a 55-85% standard cycle, that gives us 240Ah of capacity to burn through in between running the generator. Getting the same weight of Lithium batteries gives us 2400Ah, and with a 20-100% standard cycle, that’s 1920Ah. That’s an eight-fold improvement in usable capacity for the same weight. Plus you’ll get many years out of the packs with the 2000+ cycle lifetime. The primary complaint about Lithium batteries is up-front price, and rightfully so. They’re expensive. But especially if you’re going to spend any significant time on your boat, do all parts of the math — cycle time and cycle count. You might find that lithium batteries actually save you significant money over several years.

So, I’ve convinced you to buy a pile of Lithium batteries, right? Great. I’ve been watching Lithium (LiFePO4, not Li-ion) batteries for years, and they primarily break down into two main camps: US-assembled-and-warrantied packs for around 1000$-per-kwh; and Chinese-assembled-and-basically-un-warrantied packs for around 300$-per-kwh. Forum posts for years have talked about the Russian Roulette of trying the latter — sometimes you get some gold, often you get half-capacity packs, and one dies a few months later and the company has completely disappeared. So, if you go that route, way over-buy for your intended capacity and still pray. For what’s actually our home, I didn’t like either of these approaches. I wanted at least 20 kWh and preferably closer to 30, which was putting the cost of option 1 well into stupid territory, and option 2 still at expensive enough to be a real investment, without any guarantee of success.

The other problem is form factor. Many makers have been making drop-in battery replacements instead of taking advantage of the big improvement that Lithium gets you on power density (capacity per space). So you get, for example, a Group 31-shaped battery for 700-1000$, and it’s still the size of a full Group 31 battery, is only 100 Ah, and is packed full of foam to fill out the space. So, for most of the better units, if you want to get up to 20 kWh or beyond, you end up with a huge amount of space.

Many people go the DIY route, where you buy bulk Lithium cells from China, throw your own battery management system on it, and solder it all together. But especially for a liveaboard marine environment, I wanted something slightly less hand-crafted than that with at least a vague weatherproofing certification claim. I had confidence I could make the DIY approach work, but at what cost, when every time I screw up a little bit we could be in a pretty bad situation?

In the last few months, however, Electric Car Parts Company, a company that’s been around in the US for quite a while, and imports and sometimes warranty-backs various overseas options, came up with a new option: the BestGo “Preferred” packs — 12V, 400Ah, a hair under 2000$ each, with integrated battery management (a whole different topic, but suffice it to say you want this). That’s 5kWh for under 2000$ — slightly more expensive than the cheap-chinese-pack option, but a huge discount on all of the US-backed packs. It comes with a reasonable warranty, backed by the US company, and the form factor is awesome.

When I did the math, I’d be able to swap the four 4D batteries that came with the boat with four of these packs in a virtually identical rectangle (1″ wider, exactly the same length, and about an inch taller). I’d go from 9 kWh of AGM up to 20 kWh in the same space, at 2/3s the weight. And there was a nice little space next to the current battery area to put 2 more if I wanted, to get up to 30 kWh and have weight parity, with 4x the capacity. A plan started coming together. Shipping was going to be a little complicated, since they get “dropshipped” directly from China with a ~6 week lead time. So, we knew that as soon as possible after closing on the boat, we’d have to place the order and sit somewhere for a while.

12V? Bleh. Maybe 24V?

Up until recently, the only thing that made sense on your boat was sticking with whatever its native house bank was. Most boats are 12V, some larger boats are 24V, and none are 48V. You don’t want to change your house voltage. Everything on your boat is designed around it — lights, relays, toilets, macerators, electronics, your engine computers — virtually everything electric that you interact with on a daily basis.

For the longest time, I’d been assuming I’d get a huge stack of 12V battery power, run enormous cables to some huge inverters, just like Slowboat did, and that’s just life on a boat. But there’s a big downside to this approach. 12V is a terrible voltage. Humanity has been using it on mobile vehicles for decades and decades, and it’s so ubiquitous that it’s hard to change at this point. But especially for larger power demands and physically larger installations, it’s terrible. You lose so much voltage over such a short distance that everything is heat management and giant cables. Running, for example, 8 kW of power through 12V to power your inverter means pushing around 1000 amps continuous. That safely requires four 4/0 cables per lead (4 for positive, 4 for negative), and is still converting a bunch of electricity directly to heat. It didn’t excite me, either from a cable management perspective nor from a safety one. Doable, but really not ideal.

This runs into our next problem. With lithium batteries, due to some nuances of the battery chemistry, you really need to run a battery management system on top of the raw battery cells. However, most of the BMS systems don’t really support continuous draws over 100 amps. Even with 6 batteries, that’s only a 600 amp continuous draw. At 12V, that actually isn’t enough to fully feed the inverter behemoth I was looking at doing — I need around 1000 amps. However, BMSs tend to work at the same amp rates independent of voltage. So while the BestGo 12V 400Ah pack supports 100 amp draw rates, the 24V 200Ah pack also supports a 100 amp draw rate, but that’s getting twice the energy out of the pack.

I started investigating running a 24V subsystem — a main large house bank at 24V, with a tiny setup at 12V, and running converters to run power both ways. When the alternators were running, it’d charge up to the 24V house bank, otherwise the 24V house bank would live-convert down to 12V to handle constant loads. Victron makes a bunch of Orion units to deal with exactly this sort of problem, and it’s pretty manageable. However, at the end of the day, I was struggling to convince myself it was worth it. 24V halves the current requirements, but it still adds all the complexity of a new voltage level, and chargers are still fairly low-current. Even going ballistic on chargers, it was going to be ~8 hours on generator to refill a 25kWh drop. There had to be a better way.

48 Volts

Most home off-grid solutions use 48V. It’s still “low voltage” so it’s safe to work with, you get much easier and safer wire runs, and it’s a lot closer to 120V than 12V, so inverting it back to AC is a more efficient process. For off-grid home solutions, no one has 12V to deal with — you’re just storing energy to convert back to AC all day for your house. However, the more I thought about it, the more it seemed like this off-grid usage was actually pretty analogous to our higher-demand usage on the boat. We ALSO have a 12V system that has low-but-constant demands, but, over the course of a day, we lose way more power to an inverter than we do to the 12V loads. Computers, cooking in the convection oven, running the air conditioning, hair dryer, water heater, etc. It all adds up to an order of magnitude more usage than the DC stuff. So what happens if we optimize around that AC load instead of the DC load?

Well, as it turns out, the Victron Quattro comes in a few different sizes at 48V, one of which actually looks great for our needs. Significantly higher power conversion efficiency than the 12 or 24 volt models, actually smaller size and lower weight, and, best of all, a 70A battery charger in each unit (remember 70A at 48V is a lot of power). This started looking pretty compelling. For this to work, though, I needed some way to get, at a minimum, power from 48V to 12V to power the hungry fridges and electronics of the boat.

The Victron Orion line has a cheap and simple 48->12V 30 amp DC-DC converter, which would easily run our house loads 98+% of the time, at very low conversion loss. There’s also a whole pile of 12->48V battery chargers around the world to be able to charge the 48V bank from the motors. I fairly quickly pieced out a set of devices that would entirely solve this problem for me. You keep a small 12V starter “house” battery as a power sink in case you, say, run the toilet and water pump at the same time, the 30A DC-DC converter runs load the rest of the time and quickly recharges any actual over-30A-usage from the small battery.

This seemed like a slam dunk. It was a silly project, but I liked it, and it also seemed like it could be genuinely awesome. Fast charging from the generator, run anything on the boat off the inverters with pretty small size cable runs. Let’s do it. I went with six of the BestGo 48V/100Ah batteries from ECPC and got them ordered up, and got an order together from a Victron supplier for a stack of stuff.

Wakespeed WS3000

As I was about a day from pulling the trigger on a whole slew of stuff, I just kept searching for an even more efficient way to do the 12<–>48 conversions. I had an answer that I found satisfactory, but it still just felt like there had to be a better way. Something interesting popped up on one of my google searches — a PDF of a brochure that didn’t seem to be linked to anywhere. It was from Wakespeed, a company mostly known for their line of alternator external regulators. It mentioned a new product coming soon, a “WS3000”, with this picture, and no other details:

It had to be too good to be true, right?.. I immediately sent Wakespeed an email describing what I was trying to put together, and that it seemed like this WS3000 was the magic bullet to tie my whole system together, but I wanted to confirm that this was what they were going after. Amazingly, that night, I get an email back from the co-owners of the company, “The WS3000 sounds like an excellent solution for your application!”, and offered a phone call the next day to discuss a potential collaboration.

Well, turns out, what I wanted was exactly what they’re trying to build. No one has a good way to bridge legacy 12V systems and high-energy lithium 24 or 48V power banks, so they saw a market opening, and jammed a 3000 watt crowbar into it. Their timeline was getting super-early alpha hardware assembled in a month or so, which was around when my batteries were going to show up, so our needs aligned very well, if I was willing to tolerate early development software and hardware and help them tweak it all. We started planning how things would go by email while we waited for our respective ducks to get in a row.

One interesting insight Al had was to just use my port start battery as the “12V house” battery. With only a 30A converter, I needed some sort of middle buffer, especially since the windlass pulls off the house setup by default on this boat. However, with a 3000 watt converter always at the ready, that changes the game. The idea seemed interesting enough to at least try for a while, so I went ahead with that plan — merge the port start battery with the “house” positive bus, and then feed the house off the WS3000, with the port battery as just a backup/energy sink a 15 foot wire run away. As a safety measure, add an ACR setup to keep the starboard engine+battery isolated from the port/house battery, so that if something went to hell and the port side fully drained, we’d still be just fine to fire up either the starboard side or the generator and restart the rest of the boat from there to get back on our feet.

With the rough circuitry figured out, I started ordering things.

The Build

I had 6 weeks to wait for the batteries to show up, but also a ton of other projects to do on the boat in the meantime. And also, converting over to the “no-12V-house” setup was going to involve a bunch of rewiring. Finally, even when the batteries arrived, there was too much to change to possibly do in one big full day, or even a full weekend, to ensure that we’d be ready for working again Monday morning. So I had to figure out how to stage things out to give myself the best chance for success.

I spent several days going through the two engine bays and simplifying things. The factory and modded wiring in here was incredibly inefficient. Really long large-diameter wire runs to junction points that then had really long large-diameter wire runs back to near where the run started in the first place. Very questionable choices. At the end, I was able to pull out ~80 lbs of cable and end up with a more resilient setup, and get actual wire runs that were topologically similar to my ideal-state block diagram from above. I got to a place where I had both engine bays happily wired up with an ACR between them and the port loads all run to a set of terminal posts on the firewall that I could later run 4/0 cables up to the main electrical panel area when I was ready.

Once the engine bays were ready, which took way longer than I expected, I started dismantling everything possible from inside the electrical panel area to get down to the bare minimum needed to run the boat every day — basically, just the existing mastervolt 12V inverter/charger.

Eventually, over the course of a few days, two freight shipments showed up with the batteries and a stack of Victron stuff, and I was ready to go. I made a pretty serious tactical error here, and despite my plans to first merge the port battery in as the “house” battery, get that working, and then move onto installing the 48V setup, I got cocky. I can just dismantle the panel, throw the batteries in, mount up the Quattros, and be off to the races later in the day to do cleanup, right? How hard can it be. Well, turns out, quite hard, when you forget some important nuances.

To get through the day, when it came time to pull the plug on the charger setup, I wired the house setup to the Port battery, but didn’t really think about how small capacity the port battery was, nor did I have a good idea of what our steady state DC power usage was, since the factory gauges were really inaccurate and I hadn’t measured with a good ammeter or anything. So, barely a few hours into the rewire job, I realized I’d heavily drained the port battery, and quickly threw the manual switch on the ACR to join to the starboard battery to buy me some time. But this kicked off a frantic battle to get something, anything, in place that could keep the 12V system charged while I worked. I’d thought I had several more hours before I needed to be in this state, but now quickly needed a solution, or to revert to throwing the old house batteries back in to buy myself some time.

I decided to just go straight to throwing a couple of the 48V batteries in place, adding the Orion (48-12V DC-DC converter), quickly wiring it in, and using that to get the system into a recovered state so I could breathe and more thoroughly finish other aspects of the install. For those paying attention, why do I have an Orion when the WS3000 is coming? Backup. Given how utterly dependent we are on 12V power, I want at least 2 ways to keep 12V power going, especially given that one of them is in an alpha-level development phase.

Eventually, late into the night, I got one of the inverter/chargers up and running enough to start charging the 48V batteries from shore power, as well as power outlets on the boat, so we were in a breathable steady-state. I’d misjudged the length of 8 gauge triplex I needed to make nice-looking wire runs between the Quattros and the panel, as well as that I needed a stack of 8 gauge ring terminals, so I had to hack stuff together for a few days while I waited for more parts to arrive in the mail. But several lessons were learned, and a few days later, everything was finally in a full-power-usable state, though not cleaned up very well.

With the last final-gauge wiring hooked up, I was able to disconnect shore power and run about 4000 watts through the inverters for an hour before we got bored of how uneventful it was, and also the boat was really cold since we were running all the air conditioners at full blast on a not particularly warm day, so Hannah wasn’t thrilled. Then I flicked the shore power switch back on, it started charging back up at 120 amps into the 48V bank, and we were back to full in under an hour. It was a pretty magical experience to see it all come together in the end.

I spent the next many days getting the batteries properly hooked up together and secured for rough seas and cleaning up a bunch of wiring in anticipation of someday soon actually leaving a marina.

Panel Considerations

One thing I didn’t think about until much later than I should have was the electrical panel. Boats are usually designed with a front-door circuit breaker breaker + selector panel. You can select shore power (1 or multiple inputs around the boat) or generator, so that, just like with a home installation, you don’t back-feed into the grid. Then, you have a small AC panel that the inverter covers — usually outlets on the boat and the microwave. Then larger AC panels with the bigger loads on the boat that the inverter can’t cover — air conditioning, stove, water heater, etc.

This new strategy blows both of those systems out of the water. As mentioned above, the Quattro takes the generator input straight into itself, so you don’t need to “select” the generator anymore — it can just always be enabled, and can never back-feed into the grid. Also, we’re running the entire load through the inverter, so your runs go from shore power/generator through a front-door breaker, and then straight into the Quattros. Then the output from the Quattros go back and drive the entire AC panel. No more thinking about what works on the inverter or having to fire up the generator. Everything is battery-backed, usable no matter where you are.

This is neat and all, but since no one does a setup like this, there are no off the shelf panel building blocks to do anything like this. So, for now, I’ve kinda hacked my panels to do what I want — joined the “inverter” panel to the rest of one leg of the AC panel, removed the physical block between the generator and shore power connectors and now just use them as breakers, and ran the source wires back to the Quattro output for the panels. It required running a bunch of pretty large-gauge triplex wire (8 AWG for safe continuous 50 amp AC over these distances) back and forth ~6 feet between the panel and the back wall, but it worked out in the end.

Finally, I repurposed one of the 120VAC panels for 48VDC for now, mostly just to coordinate my two DC-DC converters for now, but hopefully over time I can get more 48V-native devices (like a windlass!), since it’s such a better power transport voltage.

Once I get everything more final in the coming months, I’ll probably end up contracting with Paneltronics’ custom panel wing to build a new custom AC management panel for the new reality, but this all works quite well for now, in the end.

Monitoring/Observability

As a total dork, one of the parts of this system I was most excited about was the monitoring/observability aspect. On the old boat, there was pretty much just a voltage display, current in/out display, and state of charge number to the nearest whole % point. This new system is a little different.

The Cerbo GX is a cheap addon for your Victron network that lets you connect all of the individual pieces of your power setup and upload all the data to the internet for observing, as well as convert it to NMEA 2000 messages so the rest of your boat network, like chartplotters and Maretron displays, can display all the power information as well. It has a little touchscreen addon, the Touch 50, you can get for it as well that nicely mounts into your power panel and gives you quick access to all of the info on your power system as well as deep configurability through a touchscreen. It’s a pretty great little setup.

One of the key parts of the observability is the Victron SmartShunt, which is a nice little all-in-one current shunt plus electronics to measure it and integrate it into your Victron network. So I can monitor voltage and current in and out of the low side and high side battery banks and alarm on a whole slew of different characteristics, which was really helpful in the early WS3000 debugging days. It also allows monitoring an auxiliary battery, so I can monitor the otherwise-isolated starboard battery bank from next to the port one.

It’s a nice little interface that even does a calculation of how much power is “disappearing” outside of what it knows about for generation/consumption, and calls that “DC Power”, which happens to nicely correspond to how much power is going from the 48V bank to the 12V house loads. So, at a glance, I can see how much AC power and DC power we’re using, as well as the solar generation and house battery bank levels. Then I show the 12V port/house battery voltage and SOC levels on the little Maretron display at left there, along with our two holding tank levels.

The level of insight this system provides is amazing, both live and using the VRM portal to go back in time and see what everything was doing throughout the day, even showing holding tank level history.

Generator Management

One of the primary tenets of the new system was around effectively utilizing the generator when we do run it, and another was getting to the point of just not really thinking about power usage. So, I wanted to make the generator control fully automatic.

The generator is a 12kW Northern Lights unit, and has a pretty manual panel — you have to hold the preheat button for a few seconds, then hold the start button until it catches, then keep holding the preheat button for a few more seconds until it’s running nicely, then you can let it run until you press the stop button. Being a fully-manual two-handed operation, automatic generator start/stop wasn’t going to be as easy as it was on the Onan generator from our last boat, so I had to go digging.

I found an affordable unit by Dynagen, the TG-410, which you can see mounted in the picture above in the monitoring/observability section, that allowed custom generator control basically through plugging the oil pressure/water temp sensors in as inputs and then running the start/stop/preheat outputs through relays. Setting it up was fairly trivial, once I reverse-engineered the current generator wiring harness and made a new plug-and-play harness to the Dynagen that would let me fall back to the stock controller in a few seconds of swapping a big 8-pin connector. Getting the preheater timing, start-detection conditions, and sensor curves right took a little while (and I still don’t have the temperature one quite dialed in yet), but now it starts and runs without a hint of complaint, and stops when you ask it to. The next step was external control based on battery conditions.

The Dynagen supports taking an input where 12V = generator should be running, ground = generator should be stopped; and its job is to make those conditions happen. The Cerbo GX actually supports a complicated automatic generator management system via conditional setup that, in the end, powers a relay on or off. By putting 12V on the NO and ground on the NC lines, I ran the common output to the TG-410 and it worked right out of the gate. The Cerbo GX supports standard conditions like SOC-based low/high levels for start/stop, but also quiet hours, emergency low/high levels for during quiet hours, and even time-based runs (i.e. it’s been too long, please run).

After a few days on anchor to tweak the settings, I’ve settled on 40-90% runs during the day, and 20-30% runs for emergency night settings. With these settings, ideally I essentially never have to touch the generator myself, though I’m sure I’ll keep fine-tuning this for a bit.

WS3000 Tuning

A couple weeks after I got the main power setup working, the WS3000 alpha hardware showed up in the mail and I added it to the system.

It’s been a really interesting device to tweak. I’m still working through a bunch of learnings with Wakespeed, and we’re learning as we go. The bidirectionality is a nontrivial problem to handle. You need to detect when voltage falls below a threshold and immediately switch to pulling current from the high side to feed the low side up to a setpoint, but when the voltage rises above the setpoint on the low side, you get to pick when to try pulling current off it to charge the high side. But how quickly do you pull current off? Too quickly and you drop it below the setpoint and then you need to fill back in, and get in a really awkward cycle. Too slowly and you’re letting the alternator “charge” a full battery and wasting potential charging. So there’s a bunch to tweak.

After working through a couple major early kinks, we quickly got off to the races of a working system for the basics, and getting to the finer-grained tweaking. So far we’ve largely been playing with the hysteresis between charge points, and what to put the setpoint at to maximize charging from the low side but also keeping the voltage high enough to actually put current back into the low side battery in case you overrun the 3000 watt converter and pull some capacity out of the low side battery.

A really interesting problem we discovered early on was that the preheaters on the Yanmar diesels in this boat are hungry. Each engine pulls ~200 amps from its start battery for ~5-8 minutes after a cold start. The alternators are only 80 amps each under the best of circumstances, and I mostly measure around 45 amp output at idle, leaving a huge current shortfall for the batteries to fill. The WS3000, of course, tries to fill in for the shortfall, but it can’t quite keep up, so it does draw some current down from the start battery every startup. So we’ve been tweaking the voltage setpoint to make it so that it will charge back up after the preheaters turn off. 13.2V was not enough to get anything appreciable back into the start battery, but 13.6V has been a good compromise so far.

Similarly, when raising anchor, we have double the problem, since we have 200 amps of preheater on the port battery plus the windlass pulling 300+ amps as well, vastly exceeding the WS3000’s capacity. This is causing voltage dips in the whole house setup, causing some devices on the NMEA 2000 setup to freak out whenever the windlass is powered, so I’ll need to address that pretty soon with a buck-boost converter expressly for the NMEA 2000 setup.

Next, at 13.6V, you’re pretty close to the alternator output voltage, so it’s way harder for the WS3000 to figure out how much current it can pull off to send to the 48V batteries. So we’ve found that, at 13.2V, it can pull twice as much current than at 13.6V, so we have some competing interests here in the settings.

Finally, the solar setup on the boat was originally plumbed into the 12V side, but with the WS3000 in there now too, it was getting confused with multiple different devices vastly changing voltage levels and sending current in and out, so I ended up moving the solar up to the 48V side pretty quickly to simplify things for the WS3000.

I’m sure we’ll be tweaking settings for quite a while to really dial in the last effective charging nuances, but the system is already working really well, and I’m sure this will be a great addition to other boats trying to follow in my (and the other few alpha testers’) footsteps. Hopefully this writeup gives other people the confidence to come play in these waters!

Summary/The Future

It’s been a long road, but in a Marie Kondo world, this setup brings me joy. We have the battery capacity to run the A/C all night on anchor, wake up, take a shower with hot water because we just leave the hot water heater on, then turn on a crockpot for dinner that night, run a load of laundry, throw some lunch in the microwave, and spend the day playing video games on a power hungry desktop computer. On an extreme usage day like that, we only need to run the generator for a few hours to top off again in the evening. Working full time in more normal fashion, each of us separately taking taking daily showers, spending all day on our computers on video calls, cooking meals, and watching TV all night, we can easily go two full days on anchor before running the generator to catch up. If we were really being frugal, we could go a week or more in between topoffs. And this is before I even add real solar.

Over the coming months, I expect to keep tweaking things pretty steadily. I still have a lot of optimizing to do to get our power loads down while we’re on anchor — right now, I’m running a ton of electronics all night until I dial in a good anchor alarm setup that gives me confidence. And we tend to leave things plugged in all night because we can just be lazy now and not really think about it. This is really the real measure of success here — Hannah doesn’t even slightly think about power usage, and I only barely think about it, thinking less with each passing day. Living aboard and working full time while boating brings enough challenges, we don’t want to also be dealing with power management all the time.

I was originally planning on diving right into an enormous solar setup — my measurements say I can easily get around 3000 watts of solar onto the roof and still have walking access for maintenance. I’ve wired in a new (Victron, obviously) charge controller sized for it, all plumbed in and configured. But once I saw just how long we can go on the setup without generating, I pumped the brakes and haven’t gotten around to even picking which panel to buy yet, much less getting 8 of them delivered somewhere. The ~800 watts on the roof help quite a bit on good days, so I know that quadrupling the generation should make us essentially never need to generate. So I’ll get around to it. Just not as immediately as I thought I would.

I hope this inspires others to build setups like this on their boats, and I’ll keep updating the blog as I make improvements throughout the year. Feel free to reach out blow with comments/questions, I’d love to hear everyone’s thoughts.

The Endeavour TrawlerCat 48 is a tall boat. It’s around 17 feet from the water to the flat top of the skylounge roof, with anything on top of that obviously making it worse. That flat roof is around the same height as the top of the anchor light was on the Meridian, for comparison. With harsh bridge restrictions on the great loop (19’6″ maximum bridge in Chicago, for example), from the moment we considered buying this new boat, we knew we’d have to get creative with how to put stuff on the roof and still fit under things.

The boat came with what I’m pretty sure was the original factory mount and electronics setup — a 2008-era Raymarine radar dome, a Glomex analog TV antenna booster, and a non-LED light. It was, at least, on a folding tower, so you could lower it out of the way of bridges. However, the wiring was pretty questionable — they basically just cut a big hole in the roof next to the mount and then ran the wires into the interior from there, rather than running it through the tower itself. I basically decided to eliminate every aspect of the factory setup and start over from scratch.

From the final internet and instrument setup on the old boat, as well as some new toys I knew I’d end up buying, I knew roughly what I wanted to put on the new boat:

• Three Poynting 402 LTE/3G antennas
• Two Poynting 496 2.4/5Ghz WiFi antennas
• Airmar WX220 ultrasonic weathervane
• Vesper Cortex GPS (dedicated GPS for the AIS system)
• Shakespeare SiriusXM Antenna (could also put it on the roof somewhere else, but I want as much room for Solar as I can manage)

I poked around at a bunch of SeaView options, since they seem to be the only real game in town for larger-scale instrument masts, but really nothing off the shelf fit my bill. However, I noticed a custom build section and said why not give it a shot, figuring it’d be crazy expensive.

Within a day, Jason at SeaView had gotten back to me, and to my surprise, based on my rough description, he actually gave a surprisingly affordable early price estimate that made it worth proceeding. I professionally mocked up a rough idea of what I wanted, based on the other legos they had on their site, and he went to work.

A couple days later, some neat looking CAD mockups showed up:

From there, I took some more careful measurements of the back of the roof, since he said he could easily guesstimate how far things would be able to fold, and if we should adjust the design to compensate.

He did some math, determined that it was going to stick up a fair ways, and we iterated a bit more. We lowered the sweep angle of the “wings” such that it’d be able to just clear down to the sill above the door — the best we could possibly do.

At this point, it looked awesome, and we gave the goahead and put down a deposit. 5 weeks of leadtime started then. This was all done from the rental house on Key Largo, well before we moved onto the boat, since we knew it’d have such a long lead time. So we got started ordering all of the various antennas that’d go on top, and went back to sipping margaritas every night.

Fast forward 6 weeks, and about half way through our stay at Cocoa, a pallet shows up (which YRC unceremoniously drops in the street and drives away without calling us):

We unwrapped it and got to work! The first major job was disassembling all of the old stuff and patching any necessary holes from that job. Hannah loves what I did to her yoga space all month. Also, when we went to actually remove the old folding mast, it was on what turned out to be a painted solid fiberglass plate, which must have been 5200’d down to the roof, because it took a pretty good chunk out of the gel coat when it finally pried loose. The sledgehammer was clutch for this and Hannah couldn’t believe how hard I was wailing on the damn thing.

With impending possible rain and the day waning, we decided to not be too ambitious for the day and just go for getting the plate mounted up.

A week prior, I’d ordered a foot square 3/8″ thick aluminum plate to be the backing plate for the new mast, knowing that the roof wasn’t all that thick, was just cored fiberglass, and just had some flimsy wood on the bottom to space off the roof panels for wires to run. So with the mast finally here, I took some rough thickness measurements and brought the top plate over to the hardware store, and ended up buying some 1/2″ diameter countersunk bolts and matching fasteners.

Hannah and I spent a while measuring and cutting the appropriate holes in the aluminum plate, then we roughly lined up where the folding panel would go on the roof, marked the holes, and proceeded to drill half inch holes straight through the roof. After some tweaking, the plate looked like it’d mount up well, so then we took the 2.5″ hole saw and slowly cut a huge hole through the roof right in the center of the plate. Not stressful at all.

At this point, everything looked ready to go, and so we pulled out multiple tubes of 4200 and 5200 and frantically started our work. We coated all of the exposed fiberglass with 5200, filled in all of the wiring and screw holes from all of the things we took off with the old mast, and then lined all of the new area that needed sealing with a tube and a half of 4200. We had no time to take pictures of this part, unfortunately, and we were also covered in 4200. We threw the new plate on top, quickly bolted it down to the aluminum backing plate, just as it was vaguely starting to stiffen up, and stood back to clean up and admire our handywork.

Rain was predicted later in the evening, and we were pretty exhausted, so we called it for the day and went inside to other projects.

The next day, we resumed work. We figured we should do some more final test fits at this point to see where we’d landed. We’d done some really rough “hold the heavy thing up to the wall and see how we feel about it” checks that seemed fine, and, fortunately, they held up under final prototyping.

CAD is neat. Even though I’ve been a software engineer for most of my life, and the process, decomposed, is thoroughly uninteresting at this point, it’s still sometimes amazing when you can give someone some rough napkin calculations over the internet and they can get something calculated and fabricated that lands within millimeters on your handbuilt boat. Everything looked great, so it was time to get down to the dirty work of actually building the mast.

Boy did that turn out to be an unexpected pain in the ass. The outside of the mast looks lovely, but of course the inside has sharp edges and corners and support structure that make running wires through it a chore. It took us nearly two hours, and we both sunburned the crap out of ourselves since we kinda lost track of time in our annoyance, to get everything mounted up and wire-fished through the beast. And when it was all together, we had a nice rats-nest-of-the-gods that we had created for ourselves. However, at this point, it was just an awkward game of muscle-ups to get the assembled mast, now twice the weight, up onto the hinge, and bolt it all up. Of course, we discovered that the antenna arrangement I’d picked meant that, at full droop, the LTE antenna tips JUST touched the ground, so Hannah got to hold it all up while I ran the cables into the roof, since it couldn’t rest there. Measure once, cut twice, or something.

It looked great! Just one problem.

Hannah was now able to go read a book while I spent hours running and cleaning up wiring, and testing the results.

This whole time, I’d been very nervous about the hinging process itself, since the size and location of things meant that the cord moved almost a foot through the tube when the mast went up and down. With no room in the ceiling, it was going to to be a challenge to make it so that we could raise/lower this thing several times a day in Florida and then every so often past that, without eventually snagging a wire on something in the ceiling and making for a very expensive and time-consuming problem. I decided to try out using braided plastic sheathing over the section of wire that would slide in and out of the roof hole, and spaced off the roof panel by a little over an inch, to give a little bit of play for the cables to live in. Some early testing looked promising, so, at the end of the day, we put the roof panel back up and had a drink.

It looks a tiny bit awkward if you’re really looking for it, but it’s pretty hard to notice otherwise. I’ll probably tweak it over time to try to make it a little more flat across the roof, but I’m incredibly pleased with how well it all came out in the end.

We finished off the project by ordering a rubber stop for the mast to touch down against and keep the antennas from hitting the floor while everything is lowered, and it worked out perfectly.

Hannah’s already had to raise and lower it for a bunch of the bridges coming up through Florida, and it’s worked like a charm. So, cross our fingers, maybe this project is basically all done, at least until the next gadget catches my eye…