[hamiam]

I have done it on several of my boats and it does take a while to heat up the water unless you spend a fair bit of cash on the water heater itself. Practical Sailor did a review and found that Super Stor warmed up the quickest and Isotemp held heat the longest. Its a trade off as if you get a small tank it will heat more easily but run out of water quicker and vise-verse for a bigger tank.