Rewiring a UK boat to USA specs

[Lowcountry]

Greetings, all. I've just put a Hans Christian 33 under contract. She was wired for the UK, so she's set up for 220VAC. I live in the US and will be bringing the boat over once I've closed on her. Instead of switching out the UK wiring, I was pondering the feasibility of keeping that system intact (in case I ever bring the boat back across to the Med), and adding in a separate US 30amp 110VAC shorepower service. My electrical requirements wouldnt be that great. Maybe four outlets, a water heater and a small reverse-cycle AC unit (8000BTU). This would require adding a new charger/inverter and disconnecting the existing charger/inverter from the battery bank and ship's electrical panel. All of the new service would require adding US spec AC wiring, of course, as the gauge of the UK wiring is insufficient. So basically install the 30-amp inlet, install the US-spec AC wiring, US-spec charger/inverter, water heater (or simply swapping the heating element), wiring and outlets. It doesn't appear to be too complicated to do this, but I'm absolutely not an electrician. I spoke briefly on the phone about it with a professional certified marine electrician who didn't think it would be too problematic to achieve. Do any of you here have experience with anything like this? Thoughts? What am I missing?

[Crown Royal]

I have helped do a couple boats and we did them all a bit different the main thing that helps the most is that all marinas in USA have 230v available at most of their well now. The trick is the special cord you need to get.

[mjscottinnc]

So I have to wonder why you're not considering a step-up transformer to run all the existing 220V systems on the boat? Transformers work wired up either way, 240 -> 120 or 120 -> 240 (same transformer can be step-up or step-down). Using 240 would be preferred for a hot water heater. There may be an issue for 60 Hz vs 50 Hz if there is really old equipment, if it 10 - 15 years old it will not be a concern. Most newer devices are designed for 'universal input voltage' which is 85 - 250 VAC 47 - 63 Hz.

[Lowcountry]

I'll have to research this a bit more, as I was under the impression that it would be cost and size prohibitive. A brief online search yielded some small-unit possibilities below the $2,000 mark,which would be cheaper than adding in a 30amp service. Thanks for the suggestion, I'll study up on this possibility.

[Lowcountry]

Unfortunately, here in the Carolinas and in the Bahamas, which is where I will be sailing mostly, I have not seen 220 service in any marinas. Maybe on the mega yacht docks, but not where the small fish like myself end up.

[Bean Counter]

this might do : https://shop.pkys.com/Victron-Energy...6A_p_2429.html

[asistephen]

I’m in the Uk ���� And the opposite to OP I’m looking at buying from the USA as more choices of boats at better prices in my opinion . And the plan will probably be sail back to UK for couple of years then off around the world via the usual routes do the ARC through Panama Canal and so on .

What is the rest of the world on 240 v or what ? Is the USA the same not ones on 110 or whatever it is ? Can you just buy a box that takes it all and sorts it out

Also what plugs do they use around the world are they all different ?

[Lowcountry]

Bean Counter, I'm not sure of the dimensions of that unit, but it says that due to its weight there are shipping restrictions. It is strapped to a pallet and shipped as road freight. Doesn't sound like it's going to work very well for a 33'sailboat.

[artisanmach]

I am with Bean Counter, I have that exact isolation transformer on my 37' boat and it works perfectly. it only weighs 50 pounds.

[Lowcountry]

Artisanmach, can you explain to me how you have that unit wired into your boat? 30amp inlet wired into the unit, and then the unit wired into the AC side of the ship's electrical panel? Or is it something more complex?

[Dockhead]

Why don't you give us a list of AC electrical equipment on board, and a rough schematic if you have it?


The answer really depends on what stuff you have on board.


If it's just sockets (more or less), then I think your idea is a good one. Just leave the old system (might come in handy some day) and put in a new system in parallel with its own shore power inlet and own distribution panel (assuming you have room for that, but if the system is simple, this can be small).


Most modern battery chargers will run on either 110v or 230v, so you ought to be able to connect that to the new system (and upgrade it if you can't), but don't use the existing wiring, breaker, or ANYTHING -- 110v is twice the amps for the same power.


Your immersion heater will be 4x less powerful so you might want to change that.


Do you have any permanently installed AC appliances? If not, then I wouldn't overthink or overengineer this, and I would definitely not use a transformer just to be able to reuse existing wiring to get to sockets you'll have to change anyway

[De.windhoos]

Originally Posted by asistephen

I’m in the Uk ���� And the opposite to OP I’m looking at buying from the USA as more choices of boats at better prices in my opinion . And the plan will probably be sail back to UK for couple of years then off around the world via the usual routes do the ARC through Panama Canal and so on .

What is the rest of the world on 240 v or what ? Is the USA the same not ones on 110 or whatever it is ? Can you just buy a box that takes it all and sorts it out

Also what plugs do they use around the world are they all different ?

Here you go. Full list of what country uses what voltage, what hertz en wat power plug

[Cheechako]

I agree, what is your use of 120V now? Is it possible the 220v wiring IS adequate as long as you know your amp draw limitation?
In home wiring, even for a big 1500 watt load, 120 volt specifies 12 gage and 220 volt specifies 14 gage. So not a huge difference.
You could limit the load with the amperage of the main breaker.

[artisanmach]

in my case, the isolation transformer is to deal with galvanic corrosion. it feeds shore power to my Victron inverter/charger that feeds my 30 amp panel. I can feed 120 to 120 or 230 to 120 with proper adaptor.

[Lowcountry]

Originally Posted by Dockhead

Why don't you give us a list of AC electrical equipment on board, and a rough schematic if you have it?


The answer really depends on what stuff you have on board.


If it's just sockets (more or less), then I think your idea is a good one. Just leave the old system (might come in handy some day) and put in a new system in parallel with its own shore power inlet and own distribution panel (assuming you have room for that, but if the system is simple, this can be small).


Most modern battery chargers will run on either 110v or 230v, so you ought to be able to connect that to the new system (and upgrade it if you can't), but don't use the existing wiring, breaker, or ANYTHING -- 110v is twice the amps for the same power.


Your immersion heater will be 4x less powerful so you might want to change that.


Do you have any permanently installed AC appliances? If not, then I wouldn't overthink or overengineer this, and I would definitely not use a transformer just to be able to reuse existing wiring to get to sockets you'll have to change anyway

So really the whole purpose of this is to be able to install and operate a reverse-cycle marine air conditinoner, albeit a small one (8000BTU). That's it. I live in Charleston SC, and it's intolerably hot in the Summer months, so there has to be an AC unit on board. The boat is already fitted with a diesel heater, as it is coming out of Scotland. I don't need to run any other Alternating Current appliances. There is no generator on the boat, so the juice will have to come from shorepower. I still think the most straightforward solution is the one in my initial proposal, which is to wire in a basic 30amp service. Any input from you all is much appreciated. Thank you.