Tag Archives: diesel tank

Replacing the diesel tank

Our diesel tank – Ariel is hull #7 – is located in the port cockpit locker on a shelf at the forward end of the locker. Contrary to what is printed in the CD manual, Ariel’s diesel tank was 30 gallons, not 43. It was made out of 5052 1/8″ aluminum and secured to the forward locker bulkhead with two aluminum straps. I discovered the leak in the old tank when one of the marina yard workers hollered at me for pumping diesel on the ground during my spring commissioning. Naturally, I told him he was crazy and that there wasn’t anything in the bilge but a little water. I was wrong.

After I confirmed the location of the leaks, I used a reciprocating saw to cut the tank into four sections small enough to fit through the cockpit locker opening. The original tank was 14″ wide and the locker opening is 12.5″ so there was no way to get it out in one piece. The cause of the leak was pitting in the bottom of the old tank that had eventually worked its way through, presumably caused by condensation over the years (yes, we have a fuel/water separator and do our best to keep our tank clean and full). Essentially the tank had weeped diesel onto the shelf on which it was mounted for part of the winter months, eventually dumping about 5 gallons of fuel into the bilge.

I seemed to recall reading about CD owners who cut their cockpit locker opening to fit a new tank, but I was not at all interested in that route, so I designed a tank that would drop through the opening and still provide a reasonable amount of fuel. I drew up a design and sent it to Luther’s. I requested an additional port to accommodate the fuel polishing circuit, which Luther’s added without charge. I also did my best to locate the fittings as close to their original locations so I could drop the tank in and reconnect things without having to make modifications. All three of the fuel fittings have draw tubes to minimize the chance of introducing air into the fuel pickup.

When I installed the new tank my initial plan was to reuse the aluminum straps that secured the old tank by adding shims to account for the narrower dimensions. I quickly scrapped that idea and bought 1/8″ flat aluminum strapping and bent up two straps that conformed to the new tank width.

The new tank is 24 gallons, which is plenty for Lake Michigan. I dropped it in and plumbed it in a couple hours. It was necessary to move the exhaust hose temporarily from the inboard side of the cockpit locker in order to make room for the tank to slide in. I’m very pleased with the quality and finish. It matches my supplied dimensions exactly.

Luther's drawing of the new diesel tank. Great Company!

Luther’s drawing of the new diesel tank. Great Company!

The new diesel tank in place but before the new hold-down brackets had been constructed and installed.

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