I'm looking for a 230v 50 amp double pole transfer switch so I can
switch my boat between 115v 30 amp and 230v 50 amp shore power. Any
ideas for a small one? There's a switch on the boat already that
switches between the 230v generator and 230v shore power but I can't
spot the manufacturer's name...

In case you're curious, I brought a Florida boat to SF bay where 230 v
marinas are scarce. It has a 230v ac refrigerator which I do need to
run at the dock and some aircons that I don't need here. My thought is
to put a 4kva 115230 volt transformer on board, and remember not to
try to run aircons from the 115 shore power. The marina could rewire
for a fee but if I do it on board it costs about the same and I can
take it with me.