additionally, would you use any propane in a boat?
I have a marine AC cruise air that the copper line some time ago must have broken by way of metal fatique where it meets the cruise-air unit. this is a simple copper flare with a heavy duty flare nut type of attachment.
Anyhow, I can recharge it with a flammable refrigerant that substitutes for R-22 since I have some here in the garage. But I know there would be a risk of a leak and then a possible boom.
I also think a flexible refrigerant line running to the evaporator would be a good idea.