Rewiring a UK boat to USA specs

[GILow]

For the OP, my neighbours bought their boat from Canada about six months ago. It was wired for 110 volts.

They elected for the full conversion to 240 and it has been an utter disaster. 6 months down the track and I hate to think how much money has been spent. The boat is sometimes plugged into THREE power outlets on the dock and always at least two in an attempt to keep things running

Last I heard they had only half of their aircon working, thankfully in the bedroom. The simple act of putting on the oven seems to require prayers to a number of gods and frequent resetting of circuit breakers.

I can't help thinking they should have gone the way that SV Jedi suggested, albeit in the opposite direction. Very easy to bring 240 volts onboard and then step it down to match the boat's 100 volt requirement.

[Lowcountry]

GILow, sounds like they may have a bigger boat with more complex needs than I do with my 33-footer. I need 4 AC outlets and a small reverse-cycle air conditioner, which I will buy and add after the fact, so HZ won't be an issue. That's it. There are no 240VAC appliances on board this boat like air con, washer, microwave, etc. None of that.

[Pete7]

Originally Posted by duncan_ellison

Lowcountry: It was briefly mentioned somewhere above, but just to re-iterate. A 220V wired boat has very thin AC wiring compared to a 110V wired boat.

Might be worth checking how the UK boat has been wired. I think mine has a ring main system installed during the build so similar to UK houses. Whilst this cost more, there are some advantages over say a star wiring pattern.

Pete

[GILow]

Originally Posted by Lowcountry

GILow, sounds like they may have a bigger boat with more complex needs than I do with my 33-footer. I need 4 AC outlets and a small reverse-cycle air conditioner, which I will buy and add after the fact, so HZ won't be an issue. That's it. There are no 240VAC appliances on board this boat like air con, washer, microwave, etc. None of that.

Yes, good point.

Edit: Just reread your original post, my ramblings are not useful.

[s/v Jedi]

Originally Posted by Lowcountry

I believe that the safest and most simple solution is to approach the situation as if the boat were completely new with NO AC ELECTRICAL COMPONENTS OR WIRING. So, add EVERYTHING NEW required for basic 30amp shorepower service. New inlet, new breaker panel, new inverter/charger, new 8000BTU air conditioner unit, new AC wiring, new AC outlets. That's it. Let's forget about the water heater for now, as that's an unnecessary distraction. I can always run the engine for hot water. What do you think of this approach? Let me reiterate that no components currently on board the vessel would be included in this new system. It would be a completely new, from-scratch PROPER USA-SPEC AC system. Does this sound feasible? Expense is not my top concern. Safety is.

So you're willing to take the old genset out and put in a new one, just to get 60Hz from it? Normally, it is the genset that is the deciding factor.

If a 60Hz genset is in the picture, this is the schematic; note that it's very similar and that one get delete the 2nd inverter/charger from the system, loosing redundancy and capacity but save on cost.

[NorthCoastJoe]

If you have the space for a second stand alone system.

New 30 amp feed https://www.westmarine.com/buy/marin...4?recordNum=12

New Blue Sea PN:8043 https://shop.pkys.com/Blue-Sea-8043-...UaAgxLEALw_wcB

4 duplex outlets and proper boxes
10 Ga wire from feed to Blue Sea panel
12 Ga wire from panel to outlets.

3 colors of wire, hot, neutral, ground,
It should not be hard to do.

[MarkSF]

If the boat has a ring main wired with 14 gauge, isn't that equivalent to star done with 12 gauge? The point of ring main is that the current can go both ways around the ring, so the wiring shares the current.

[Sailing Drummer]

To add to what NorthCoastJoe says, add a residual current device between the 2.

[Lowcountry]

Originally Posted by s/v Jedi

So you're willing to take the old genset out and put in a new one, just to get 60Hz from it? Normally, it is the genset that is the deciding factor.

If a 60Hz genset is in the picture, this is the schematic; note that it's very similar and that one get delete the 2nd inverter/charger from the system, loosing redundancy and capacity but save on cost.

There is no genset on this boat. The only AC appliance on the boat is the water heater. That's it!! It has 7 AC outlets, but I'm only talking about adding 4. I also want to add an 8000btu US-spec reverse-cycle air conditioner. I'm trying to add 4 outlets, all new US spec AC wiring, new charger/inverter and 30amp service to drive it. It's a simple system I'm talking about.

[s/v Jedi]

Originally Posted by Lowcountry

There is no genset on this boat. The only AC appliance on the boat is the water heater. That's it!! It has 7 AC outlets, but I'm only talking about adding 4. I also want to add an 8000btu US-spec reverse-cycle air conditioner. I'm trying to add 4 outlets, all new US spec AC wiring, new charger/inverter and 30amp service to drive it. It's a simple system I'm talking about.

Wow, you don't even have a battery charger? Well, that changes things. You can just put some breakers in to wire the outlets to a shore power inlet.

But when you start installing equipment with direct connections, or any battery chargers, you do need to look at the isolation transformer or at least a galvanic isolator so that shore power isn't going to eat up you propshaft etc.

[Tillsbury]

Originally Posted by 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.

It’s too heavy for normal post, but it’s only a box weighing 20kg or so. Definitely get one of these, which aren’t a bad idea in the first place (protects you and your boat from dodgy marinas and neighbours). It’s the gold standard for an AC installation.

A completely side benefit is that you can feed it what you like. So just install it immediately after your shore connector, and set the jumpers internally for 110v input 220v output. Leave your entire boat as UK spec (since you will have entirely thin wiring in it). Buy 220V versions of anything you need — AC, water heater, etc. You can run the inside of your boat entirely at 220V even though the marina only has 110V.

Bonus for you or your next purchaser: when you travel with the boat to a 220/240V country you only need to change the jumpers to 240V input and everything will carry on working perfectly, and continue to be protected.

[B_Hunter45]

I bought a 220V boat and converted it to 110V. BUT!!! this was a Hunter, made in the USA with a USA harness. Converting was a breeze. Water heater element, a few relays and microwave. So if the system is simple, no gen, no A/C then convertign a 110V boat to 220V is a piece of cake. Converting a 220V to 110V if the electric harness was built to the 220V standards is going to be very costly.

[Lowcountry]

Originally Posted by s/v Jedi

Wow, you don't even have a battery charger? Well, that changes things. You can just put some breakers in to wire the outlets to a shore power inlet.

But when you start installing equipment with direct connections, or any battery chargers, you do need to look at the isolation transformer or at least a galvanic isolator so that shore power isn't going to eat up you propshaft etc.

S/V Jedi, thanks again for your helpful responses on this thread. I really do appreciate the input. Yes, there is currently a charger/inverter on board, but I had planned to replace it with a US spec one. I am still strongly considering what Tillsbury suggested above, however. Keeping it 240, addinflg a Victron 3600 iso transformer and buying a Euro air con unit. I still have time to figure it out, as I'm not even home from viewing the boat in Spain yet. I plan to sit down with my marine electrician and go over all of these options to determine what works best for me. Please keep the discussion going, thanks!

[boom23]

I have not read all the posts, but here is what I have done on previous boats.

I have added a Victron Isolation transformer, which can (up or down) convert shore power voltage (does not change Hz) to whatever the boat systems expect to see.

I have added a 120V/60Hz inverter to power the new 120V plugs or circuits.

Remember that 230V circuits may have thinner wires from the factory due to lower amp requirements. You can either restrict amps or run new heavier gauge wires for the new circuits.

Resistive appliances (water heater) do not care about Hz. Most AC units work at 50Hz or 60Hz. Microwaves and clothes washers tend to care about Hz, and you might shorten their life by supplying them with the wrong frequency, but they are comparatively cheap to replace. You can read their power requirements on their motors or manuals.

[Lowcountry]

I will also say that I had about $7,000USD budgeted for all of this, but I'm flexible on that.