No, the autotransformer really doesn't do much for you. As used in the article it is really for American vessels that want 120V from a Euro 240V (or a US 240V) connection.
Probably the simplest, in overall terms, is just to add the little brother 3600W Victron isolation unit to your system. Set it up for 120V in, 240V out. Hardwire your 120V shore power cable to the input. Connect the output in parallel with your existing isolation transformer (put a switch/breaker on the output of each so you don't waste power feeding the xfmr that is not in use).
If you are at a dock with 120V power you drag out that cable, connect it, and just carefully monitor
your load so you don't exceed the capabilities of the 120V 30A circuit. If you are at a dock with 240 V power you drag out the cable connected to your existing 7000W unit.
It's extra expense and weight, but the 3600W can be had for about US$700 and it saves any fiddling around, allows long-term connections over the winter if needed, etc. You might be able to save a little getting something other than the Victron product, but not a ton.
That's an option I hadn't thought about and has the benefit of being a clean permanent solution if wired with a transfer switch and breaker as you advise.
The other benefit is that I am not buying a 120V charger, that can not be used if on 230V Generator.
Presently I have the 70a Multiplus charger and an old Skyla 50 that was purchased in 1991..... still works fine, but not what I would want to depend upon if the Multi went down.
I have plans on buying a 2nd Multiplus, since I've switched to induction cooking. So maybe time to retire the Skyla and put in the 2nd Multi, with the 3000W transformer as a step-up as I have the space to mount it in same area as the 7000w
We don't know how long we would keep the boat in the PNW and may head down to Mexico to defrost instead of returning to Asia, so this solution feels right...Thanks
For us, we have a 12V system and only 520Ah, so we have a 30A charger. Even if we happen to come in deeply discharged it can get us pretty much topped up overnight. We rely mostly on solar
, it does pretty well during the summer. And there's not a lot of sailing on the inside, so the motoring makes up any deficits.
Yes, I expect to motorsail a lot
We love Petersburg, and the marina is right in town, but Wrangell has a few more options for eating out if you like meals
away from the boat and are planning to spend the winter. I doubt you could find a slip in town in Wrangell, but you might be able to find one at Heritage Harbor just south of town. Shoemaker is several miles south and not convenient without a vehicle. IIRC Denali Rose (here on CF) keep their boat in Wrangell.