We also converted our aft water tank to diesel and at the same time re-plumbed the fuel lioness. It accomplished a number of objectives.
Since we had a diesel generator, we added fuel pickups from all three tanks. The original Hylas system had a single pickup that provided fuel to both the main engine and the genset. Adding the second pickup to each tank was easy because the tanks already have threaded tank inlets. Just need to solder a tube to an elbow and cut to the correct length. For this second pickup we ran the tube to the bottom of the tank which proved very valuable. When the genset ran it was pulling fuel from the very bottom of the tank, so it was constantly taking any bad stuff in the tank, unlike the main engine pickups which were a little over a 1/2inch off the bottom. If the genset fouled it isn't a crisis.
Also by having a pickup on the bottom we can easily check the quality of fuel in the tank because we also added a transfer pump and racor filter and plumbed them to allow polishing the fuel in each tank separately. When you take on fuel just run it through the polisher for a few minutes and then check the racor for water or other pollutants.
Also, the pickup on the bottom allows emptying the tanks completely. Generally we switch tanks when we get down to the bottom 20%. That leaves a lot of fuel unused. With the transfer pump we can completely empty each tank.
One other addition was a hand pump in one of the pickups, just a simple squeeze bulb like in the dingy fuel line. This makes changing fuel filters very easy. Change the racor filter and refill with the squeeze pump. Then change the engine mounted fuel filter and refill with the squeeze pump. Some people don't like using these hand pumps because they can fail, but if the hand pumps are in a genset pickup or an extra pickup it doesn't really matter. Also, if you plumb with imagination the hand bulb pump can back feed the other pickups and blow out any dirt at the inlet to the pickups.
Also, when re-plumbing you can arrange it so that both the main engine racor filter and the gender racor filter can feed the main engine. Then by throwing a valve or two you can switch filters while underway.
Finally, we used this project to relocate the manifolds from the area of the nav station floorboards to the area above the two fuel tanks just forward of the companionway steps. The floorboards are much easier to access in this area, so doing any of the above is simplified.
If anyone wants a schematic of our fuel system please send me an email at
burtpreston50@gmail.com.
After 40,000 miles the tanks were very clean and we never had a problem with fuel, despite spending three months each year in the Bahamas.
Burt Preston
Exuberant
H44-83