Re: Storage hot water system

Bill Kinney


The answer is "it depends."  How do you use your boat?  If your boat spends most of its life connected to shore power, and if that is the only place you want to use hot water,  then an electric tankless water heater can work well.  

For a cruising boat that typically is off the grid, tankless systems are very problematic, no matter what the random youtuber might say.  If powered by propane, you'll be shocked how fast a propane tank empties. That might not be a problem if you are cruising in a populated area, but once you go remote, you'll find it necessary to go without hot water at least sometimes. Safe installation of a propane water heater is not impossible, but it is very difficult. Aside from the issues with additional propane plumbing, you also need to arrange exhaust in such a way that you can be 100% sure it can never be blown into the living space.

If DC powered, you'll put a huge load on your batteries, and if powered by AC, you'll again put a huge load on the batteries, and likely need a significant upgrade to your inverter.  Of course you COULD run the generator  every time you wanted hot water, but that would hardly be efficient or convenient.

Another input for "it depends" is where you use your boat.  For us, we are usually in climates where we don't really care about domestic hot water at all. We have actually been at the dock here in Grenada for about 2 months and haven't even turned on the hot water heater. We find that water coming out of the tap at 30C is quite sufficient for our needs. When we have been in colder climates, our normal cycle of running the generator for 90 minutes every other day gets us all the hot water we need.

Bill Kinney
SM160, Harmonie
Port Louis, Grenada.

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