hello Mjak, It really depends on how you use your boat and what you want hot water for. If you're always at the dock, plugged into shore power, definitely get an electric hot water heater. If you anchor out and run your engine to charge your batteries, then get one with an engine heat exchanger so you get hot water for shower and dishes at the same time you generate power. If you have solar and/or wind generator for generating power, you can still get hot water from engine heat exchange just from the time you're motoring into an anchorage. Make sure you get a marine water heater, such as Raritan (don't know what they have in land of Oz). On our 25-year-old boat the previous owner had installed a cheap Sears electric hot water heater to save money, and it had rotted out in the marine environment. My advice is to get as big a water heater as you have room for. The water will stay relatively hot, especially in warm environments, and make everyone happy to have a bit of hot water for a navy shower, etc. Also, a 20-gallon hot water heater increases your water capacity by 20 gallons....
Capt. Lee Carlson
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