Fuel Delivery Twin Engines

[db2]

I would like to invite comments on the fuel delivery system of my Californian 42LRC with twin Perkins 6.354Ts. Each engine runs on 2 tanks, the 4 tanks are not interconnected. The port tanks are 150 gal new aluminum. The outlets are at the bottom and there is a manifold with 2 petcocks. The returns are at the top and there is a manifold, but no petcocks. Obviously, the design is to run the port engine off of these 2 tanks simultaneously. The starboard side is the same but the tanks are steel and there is a tee after the filters to run the generator.
I guess I could just run it this way but I am tempted to at least install petcocks for the returns so that I can run each engine off of either or both tanks. Should I consider connecting the manifolds and setting it up to run the engines off of any of the 4 tanks? Also, the fuel lines are well made rubber with swivel gas type brass fittings with swagged collars. should I stay with these if changes are made or are barb fittings with hose clamps OK. I have a small electric pump with filters that I was planning to use as a transfer/polish system, but it would certainly make the plumbing more complex.

 

[Scary]

I would set up a fuel management manifold

Both of my twin engine boats have been set up to supply and return fuel to any of the fuel tanks. Detroit and Cummings engines return fairly large amounts of fuel. This allows you to transfer fuel if it is needed. Usually fuel is drawn from pickup tubes from the top of fuel tanks. The reason being that debris and water would settle to the bottom of the tank and not be picked up by the engine. The generator pickup is usually set higher so to leave emergency fuel below its pickup. Normally the generator would run out of fuel first not leaving you stranded. My current boat only allows the generators to pick up from a dedicated 290 gal tank which I can transfer to or draw fuel from for either of the mains. The mains have four tanks to draw from one 490 gallon keel tank and two 400 gallon saddle as well as the 290 keel tank for the gennys, Total of 1580 gallons. A 57 ft Carver I delivered to Newport carried 800 gal in two tanks that were connected with a balance line that could be closed . Each engine draws fuel from just one of the tanks and returned to same tank. The balance tube was supposed to even out the fuel from tank to tank. Lots of ways to skin a cat.

 

[markpierce]

I have four tanks supplying a single engine, using one tank at a time (or any or all if desired), returning fuel to same, switching tanks on occasion to avoid a list. Find it easier to manage using a single tank at a time. Have separate manifolds for fuel toward engine and returning to tank(s). With two engines, you're likely to prefer a slightly different strategy.

 

[Edelweiss]

I would like to invite comments on the fuel delivery system of my Californian 42LRC with twin Perkins 6.354Ts. Each engine runs on 2 tanks, the 4 tanks are not interconnected.

Sounds like somebody did some modifications along the line.

Depending on the year and style of your Californian there could be variations. But if your boat is a Marshal tri-cabin with twin port and starboard aft cabin beds, you would of had two 120+ gallon tanks under each bed. The port tanks feed the port engines and the starboard tanks feed the starboard engine, with a tee at the filter that feeds the generator.

Originally there would have been a cross over hose with a valve on either end, between the two port and two starboard tanks to equalize the fuel levels. Sounds like someone removed this line. This could cause your boat to list a little if you run the generator a lot. Unless there is a reason not to, I would re-install the cross over system.

The swagged collar fuel lines are bullet poof for the most part. I had one hose start weeping right at the fuel filter, probably caused from over flexing, which I replaced. The rest outside of the engine room looked fine. There is a 1 1/2" hose barb under that swagged collar and as a precaution I added a stainless steel clamp to each behind the collar anyway just to be safe.

My boats over 35 years old and I've never had a problem with this setup. Plus it corresponds to the KISS principle which is a good thing!!