This picture could have been a Photo Forum Project all by itself. To remove the lower aft partition from the Head you have to remove almost all of the trim and the cabinet outboard of the sink. Its not hard, just lots of screws and a pile of pieces.

View into the Starboard Locker through the Head

I started off by making a full size three dimensional cardboard template of the tank I planned to use.
(If you adopt this project to another boat DONT skip this step, originally I thought the tank would have the 14” side up, after putting the cardboard tank in place it turned out that the 10” side had to go up.)

Finding out where the fittings had to go was made possible only by having the full size unit in place. Once I found out which side was up I marked the bottom of the template on the hull. I added a half an inch for the base thickness and a second half inch for room above the tank for straps and padding.

The blocks are 8” long pieces of 2 x 4 with the top cut on a 20 degree angle to approximate the flare in the topsides and the back sanded to match the hull contour at each location. They are bonded in place with 3M 5200.

Base Blocks in place

After the blocks were in place I used a piece of half inch plywood to support the bottom of the tank. As you can see it has been scribed to match the hull, had the “T” nuts installed for the hardware and given a coat of West Systems epoxy. All of the hardware has to attach from the bottom since the tank and base have to be installed together. The “T” nuts were installed into counter bores to keep them from contacting the tank.

The Base

The brackets were mace of 1/8 inch by 1 ½ inch stainless angle, cut to the required width. The upper brackets attach to the toe rail bolts.

End Brackets

Of course all the toe rail bolts didnt happen to be in the right location, so the center bracket spans two of them. The extra holes are there because I wasnt sure exactly where the lower bracket would end up, and its a lot easier to drill stainless on the drill press at home.

Center Bracket

Here is the base installed. The three straps in the photo are 1/8 x ¾ inch stainless. There will be a fourth one installed opposite the center one on the inboard side attached to the locker lid hinge screws and four angle brackets attaching the base to the hull blocks.

Base installed

Here is the tank, it’s from Raritan Engineering, Part Number TK239, 10” x 14” x 48”. You send them a sketch and they install the fittings where you want them. These are all on top. This causes a few small problems with access and means that you need a dip tube in the pump out, but it also means fewer potential leaks.

28 Gal Tank

The tank is in place for a test fit of all the parts! I still have a few things to do, like relocating the deck fitting for the pump out, installing the plumbing and putting the head back together.

All in all this isnt to bad a job, especially since it doubles our capicity fron 14 to 28 galllons.

All the stainless came from McMaster-Carr, and if you havent visited their website do it. http://www.mcmaster.com/ they are an industrial supply house with no minimum order, a great search engine and a catalog that is about 4 thick. They have just about everything and ship UPS most oders are filled and shipped in less than a day.

The last picture!