Included in “all the comforts of home” boating is hot water. So it is unfortunate that our water heater sprung a leak. But it is fortunate that it occurred toward the end of the fair weather boating season. The water was slowly leaking from the bottom of the heater which, according to internet researching, is evidence of corrosion. This type of leak (as opposed to coming from a fitting or a hose clamp) is not reparable and the only solution is to replace the water heater. This original water heater lasted nine years. It would have lasted longer if the manufacturer included an anode to prevent corrosion. Most manufacturers now include anodes. It was a low cost water heater that wasn’t built particularly well. They still make them and I could have installed the same model but there are much better units available. I decided to go with a Torrid. They are manufactured locally on Bainbridge Island and are extremely well made. And they include an anode. Purchasing it was the easy part.
Before I could install the Torrid, I had to remove the old heater. In order to do that, I had to remove the water maker, the low pressure pump for the water maker, an 8D battery weighing 160 pounds, and the support holding up the engine exhaust tube. The old water heater is the square aluminum box to the right in the photo.
So I removed the water maker, the pump, and the battery and set them aside and out of the way. The floor of the cabin has removable panels that make it much easier to get big items in and out of the engine room. Here is the old water heater ready for the trash. 
With the shelf empty, I patched all of the holes and repainted it. It is now ready for the new Torrid.
I have been having intermittent issues with that 8D battery and since the old one is already out, I got a replacement for it. Evan helped the old man with the heavy lifting.
Now to put it all back together and hook up the new Torrid. The plumbing is copper so the push-to-connect fittings made installation much easier. Like most marine water heaters, this one has a heat exchanger that allows the water to be heated from the engine. Otherwise, we use the electric option.
Finally I added an expansion tank and an anti-scald valve. The expansion tank takes the pressure off the pipes as the water expands when heated. Using the engine to heat the water results in super hot water at 180 degrees, which will scald you very quickly. The anti-scald valve mixes cold water with the hot water to maintain a safe temperature at the faucets.
Here are pics showing the addition of the expansion tank and the anti-scald valve.
And the finished installation:
Fiddler 