Thursday, June 23, 2011

Fuel system

This is going to be the first of a few posts relating to my fuel system. I'm glad I did not bid building this system for someone as I'm finding this job burning up a lot more time and material than I would have guessed.

The first order of business for building the fuel system were installing the fill pipes. I have four integral tanks in the engine room with a capacity between 1200 - 1300 gallons. I have one 200 gallon tank that I will use as a day tank. The day tank will supply the main engine and generator with fuel. On the aft deck of the boat I'll have two fill locations, one fill for the starboard tanks, and one fill for the port side tanks. Both the port side and starboard side fuel fill pipes have ball valves in line to direct fuel to either the forward or aft fuel tank on each side of the boat. When I want to fill the forward port tank, I close aft ball valve and open the forward valve. Likewise, when I want to fill the aft port tank, I close the forward ball valve, and open the aft valve. When the tanks are full, all the ball valves on all the fill lines are closed. The fill pipes are steel pipe, 2" sch. 40.

The tank vents are 1" steel pipe sch. 40 and will exit the boat with the fill pipes and terminate at the fill stations.

After the fill pipes were fabricated I turned my attention to the fuel transfer piping. With four tanks on board, and one of those tanks being used as my day tank, I have to be able to transfer fuel from any one tank to any tank I desire. In order to transfer fuel I'll utilize an electric pump with a manual pump as my back up. Each tank has a dedicated pick up tube that extends to about 1" above the tank bottom for the transfer system. I added a second pick up tube to each tank to give me the option on using the second pick up tube for feeding the machinery while still having a stand alone fuel transfer system. The fuel transfer system has a large Racor filter that will clean the fuel and separate any water in the fuel before the fuel goes to the day tank.

I wanted to get a decent flow rate out of my transfer system, and because I was a little nervous about friction loss in the transfer pipe, I used 3/4" sch. 40 steel pipe for the transfer system.

I'm in the excavating business, and I'm always calling to have underground utilities marked before I dig on a job site. The marking companies spray paint the location of the various utilities on the ground using the following colors: red for electric, blue for water, yellow for gas, orange for cable and phone, and green for fuel or oil related. Given I have to paint the pipe to protect it, I have chosen to paint all the fuel related parts in the engine room green.

There is a lot to the fuel system, and I feel as if I got a good start on my first week of working on it.


  1. Conall,

    Looking good!

    Designing, fitting and welding the fuel system plumbing for my six tanks plus a day tank added about a month to my project. I spent many nights dreaming about piping...

    I put the specs for the manual fuel transfer pump that I'm using under comments on my blog. I would consider that the ability to transfer fuel is a critical system and there needs to be more than one way to do it.

    Have you done any electrical on your boat yet? I'm just getting into this and it is requiring a lot of study. Especially when it comes to AC and DC in the same hull.


  2. Thanks Peter,

    I agree, the fuel system is sucking up huge amounts of time. I wish I had socket welded and made the fill, transfer and return lines internal to the integral tanks ( Oh well, maybe on the next one I build).

    I have a small start on the electrical system in that I have some AC and Dc behind the hull liner. All wire is home run to wheelhouse and distributed from there. Batteries in engine room w/ 1000 amp hours @ 12V. Inverter. 10kw diesel genset. 4kw generator powered off the hydraulic system when the main engine is running. AC and DC panel are separate panels in wheel house. Sub panel in ER for both AC and DC.

    My order of work is complete fuel system. Complete hydraulic system. Complete steering system. Complete water system. Start electrical system.

    Nigel Carter has a good book on electrical system. He has some good diagrams on balancing the system and how to handle charging loads.