Diesel Fill Manifold

I would like to set up the diesel tanks on my 46’ motorsailer so that the port and starboard fills are connected to a common manifold, enabling both port and starboard tanks to be filled from either side of the boat. However, I am not sure how to go about this.

If the fill pipes went directly and independently to their respective tanks, the fuel would flow straight down for about 18” and into the tank. The only way I can see to move the fuel from side to side is by installing a horizontal pipe athwartships, maybe 12” below the level of the deck fills. It seems to me fuel is just going to back up and spill out the fill with this set-up. Does anybody know how this is typically done?

Regards,

Sea Jay

 

Connect both tanks with an overflow pipe near the top of each tank. You can fill both from one side and use the other filler neck as a vent.

If you want to be able to equalize the contents after a lot of fuel has been drawn from one tank, connect the tanks near the bottom as well and use a ball valve that is normally closed.

 

You won't get better advice than that! .. and save money on small fills and hose and suffer forever. (the other fill can't be the only vent - just for filling)

 

CDK,

I'm not sure that will work for me as the tanks are polyethylene and I'm not wild about poking holes in them. (I suspect the overflow pipe you suggest would have to be in the 1-1/2 to 2 inch range). But maybe I could use your idea in another way...I could place two small tanks under the fills with the overflow pipe you suggested...really just a big bulge in the connecting pipe to relieve pressure and capture splash. I'll have to think about this.

Mark,

I agree about large fills!

 

It's starting to sound complicated, Seajay. I think it was assumed that the tanks didn't exist yet. Would it be worth it to you? Unless you completely fill up, fuel will favor one side and your crossover hose will need to be big, as well.

 

My suggestion is only useful if there an inspection hole or tank element hole large enough to position and hold a thru hull fitting plus neoprene ring, while someone else puts a ring and nut on the outside.
I did this once in a tank where I underestimated the distance from the hole to the wall and used a bent piece of wire to position the feed thru. It's possible.....

 

I think I may have found the solution. I went and dug out the tanks from my storage area. It had been some time since I looked at them and when I did, I remembered that there was an 1-1/2" NPT insert on one end, near the bottom of the tank. I missed this detail when I ordered the tanks and really wasn't very happy when I saw it. I would have prefered to have had all of the openings on the top. Well, maybe it will all work out fine. I was going to have to close off that insert anyway, so now I'll just use it for the cross-over pipe.

 

Crossover is good but do valve.

 

IF you are neat a tank mfg place , they will usually spin whatever fitting you desire into the tank for $20.00.

Its a 5 min job , cut hole with rotary saw , and a 1 1/2 HP router installs the fitting in about 15 seconds.

You could do it at home IF you made a plug to fit the new fitting that allowed it to spin ,therefore heat, melt, and weld itself in.

 

Mark,

Valve - yes!

FF,

I watched Ronco spin on the fittings for my water tanks as you suggested. Pretty slick. But as noted above, I found an insert at the bottom of the fuel tanks that will work for me. Thanks for the input anyway.

Regards,

Sea Jay