R&R of CT 41 hot water heater

[Found at Sea]

I was having a great weekend on board my CT41 "Dawn Treader" when I noticed the water pressure pump was running more than normal. I filled the tanks thinking that they must be low and following the fill-up my pump began to cycle on and off about every 30 seconds and hot water started showing up in the bilge. I began tracing all of my hot lines to find the water heater tucked back under the cockpit deck on the port side of the mizzen mast was leaking big time. Quite a bit of rust on the bottom of the tank and copious amounts of steaming water lead me to believe that the old unit had failed. Probably seeping for some time. Those of you who have the same arrangement will know that access is quite limited for replacement. I have a second tank also on the port side forward of the stove under the counter in the galley but it never worked and had a tag on it indicating it was abandoned some years ago. Advise from the CF community regarding R&R of either of these tanks is appreciated in advance.

Many thanks,
Found at Sea