Anyone who is familiar with my boat or has followed my projects over the years should already be aware that I have an outboard engine with a 3 gallon steel running tank that sits in a small well in the cockpit. Access to the well is easy, and through a hatch that lifts up as long as the tiller is raised to a near vertical position. In this hatch is the fuel tank and the manual primer ball to pump fuel to the engine, and herein lies the two main problems with the design. The first issue being that to prime the engine, which is required anytime it has either been tilted up or has not ran in a while, you have to raise the tiller to near vertical to get to the primer ball, which is easier said than done when you are ready to start the engine before dropping sail. The second issue is that the tank only holds 3 gallons of fuel, and for those summer days where you are motoring long distances with no wind, or traveling through places like the East River by NYC, you can easily wind up needing to refill the tank while underway, which also cannot be done without the tiller raised nearly vertical, and cannot be done without someone else to take the helm (tiller pilot couldn’t help since the tiller must be raised out of position).
It has long been my desire to add a larger tank to the boat below deck to eliminate the issues mentioned above, but a fairly daunting task since it involves so many individual additions to the boat to do a proper job. I had considered the project for the last couple years but kept putting it off because I just wasn’t ready to tackle this large project yet, when the decision was firmly made for me last fall. A few weeks before hauling out I pulled both the running tank and my 5 gal can out to fill up on the fuel dock when I noticed the metal seam at the bottom of the running tank was looking pretty bad. It was already rusting when I bought the boat, and the surveyor even suggested I replace the tank before it got much worse. The dock master also noticed how bad it looked and commented that he thought it was time for a new tank. How prophetic he was, as a few weeks later when I went to move the boat to the working dock to have it hauled out, I had a puddle of gas under the tank where it rusted through the seam and leaked out about 3/4 of a gallon of fuel, most of which had evaporated leaving me a oily mess to clean up. It was finally time to redo the fuel system.
I was going to have to address the fist issue with getting access to manual primer ball to prime the fuel system as a whole new issue since the tank was going to be relocated down in the lazarette and the primer ball would be hard to access. I decided that I wanted an electric fuel pump to prime the system, but maintain the manual primer ball for cases where the electric pump may have failed, or just otherwise isn’t desirable to use, and since I was going to be adding a larger tank where the fuel will likely sit for a longer period of time, and be out of sight where visual inspection of the tank is difficult if not impossible, I was going to need a good water separator and fuel filter. I decided on the following schematic.
Now that I had a plan, I hard to start putting together the parts to make this all work. Earlier in the year I had been talking with Gary Jones, owner of the 1992 Hunter 27 Wind Dancer from Missouri, and he was having similar complaints with his 3 gal tank, and was about to have RDS Aluminum make a new tank for his boat. Early this spring I got out to the boat prepared with a bunch of space cardboard and measured how much space I had and built a mock tank out of cardboard to make sure I was able to fit it into the lazarette and slide it into position behind the rudder post and underneath the swim platform where I wanted to install it. Once I had my measurements figured out I setout to draw out my new tank design, and this was what I came up with. I’ll get to the actual installation details a little later.
Having grown up around boats I knew that the two most common challenges with internal fuel tanks, aside from keeping the fuel clean, were A) knowing how much fuel is actually in them, and B) keeping the fuel level sending unit in working order. Luckily for me there have been significant advances over the years and the traditional resistive meter with a float on an arm is no longer your only option. The new “gold standard” of fuel level sending units is now the WEMA sealed units that use a floating magnetic ring riding over a sealed tube with sensors inside the tube that can detect the position of the magnet around the ring. Since the electrical components are completely isolated from the tank, and it has virtually no moving parts, the only thing that can likely go wrong is the magnetic ring gets gummed up and stuck to the sensor tube.
Having confirmed that RDS installs WEMA sending units by default, I was just left to approve the final drawings and start ordering all the related parts I was going to need to make everything work.
Continue on for component details and thru hull fittings in Part 2