Here's the dealio, I put a blanket on my water heater at home a long time ago and noticed my gas bill went down about SEVENTY PERCENT! !
So I put some of the same blanket material around the water heater in my van and noticed somthing: I heat up the water in the van water heater and then turn off the water heater - 24 hours later - the water in the van is STILL HOT!
So I was thinking, Hmmm - What if I heated up water for the boat only once a day? Maybe I could make a system where you only need to run the heater once and have hot water all day?
So I got that pressure can thing that Kevin told us about and I wrapped it in a water heater blanket and tested it - sure enough - after heating the can thing on the boat stove I came back the next day and still had hot water. The only problem was that the can needed to be portable so it could be placed on the stove once a day and the blanket could not be on the can when the stove was on or it would hurt the blanket - I needed to have the blanket somewhere else - so I thought "What if i wrapped a metal trash bucket with the blanket and put the pressure can thing in that?" So I tried it and it worked. So I figured the best place to mount the metal trash bucket with the blanket on it was in the galley.
SOOOO long story short - you heat up the water in the am or evening (like just before you take your shower) and your good for the whole day or the day after. 30 pumps will shower two people or hot water to use at the sink all day long.
I thought it would be nice to have hot running water right at the sink whenever you want it. Remember the old Dishmasters from the 70's?
It's kinda like that -