The 11-gallon hot water tank fitted to my schooner was insufficient to supply both bathroom showers when we had guests aboard. This long article shows how a second tank was installed to double the capacity to 22-gallons. The water is heated both electrically and from the boats engine and is even enough to fill the aft bathroom bathtub.
2315 words 7 pictures. Price for this article $10
DOUBLE YOUR HOT WATER CAPACITY