Fuel Transfer Idea

[Notorious]

I do an annual long distance trip with fuel on-deck in bladders. I typically transfer the fuel via a 120 volt pump into the aft tank through the fuel fill on the gunnel. This system works alright but if the weather is up water can get into the fuel fill.

I'd like your thoughts on tapping into the fuel return system to empty the on-deck fuel. The return lines are relatively small diameter but it would allow an easy connection the either fuel tank.

Any problems with this strategy besides the small diameter of the return line?

Thank you.

[Glory]

If your boat is Detroit Diesel powered you are returning more fuel than you use in the return lines.

I may be possible to to tap into the fill line below deck, I would install a valve so when not in use you don't make a mess when fueling.

[racclarkson@gmail.com]

Used bladders on a previous boat. Simplest and safest for me was to make a threaded fitting to replace filler cap and quick connect hoses to it and bladder. You’ll have to get a machinist to thread a short nipple as the filler is not NPT. Not a hard or expensive job.

[Pascal]

You should be able to find banjo nylon fittings that screw in the filler. I ve bought a 90 degree elbow to make pumping out easier, male thread to the fitting and banjo on the other end to connect the pump out. You can then use adapters to go to smaller size hose as needed

[rustybucket]

We transferred fuel regularly on our old 38 Ocean. I mounted a dc transfer pump (old fuel priming pump) in the bilge and a 3 way valve so I could direct which tank we were transferring to. Then from the transfer pump I ran a hose to under the salon couch. It was about 15' long and coiled up in storage under the couch.

One end of the hose was connected to the pump, the other end was free, so I could pull fuel from whatever I wanted to no matter the seas. We used everything from Drums to bladders and I made connections for all of them. We called the hose the 'straw' b/c that's basically how we used it. It was the boats straw to suck down fuel.

For your situation you could just have the hose and a flared fitting on the end of it to connect directly to the bladder. It doesn't really matter what you connect to, a return line would be fine, so would a supply line (as long as there is no check-valve between your connection and the tank). Also, most of my tanks have a plug or two in the top that could easily run a new line to.

If bad weather is expected you could hook everything up when you are at the dock so all you have to do is throw a valve and hit a switch to begin the transfer.

Our transfer rate was very slow due to the type of pump but we didn't ever have to worry about priming the pump. Generally speaking we were never in a hurry to transfer. Usually started the transfer when we were about an hour from our destination (oil rig) so it was finished when we arrived and we could move the bladder/barrel out of the cockpit.

[Boatsb]

Get a spare fuel fill cap and drill and tap a fitting into its top. Replace the one with that when filling. No water will get in.

[Pascal]

No need to drill and tap. Get banjo fittings. That's what I use to pump out. These elbows come in different threads. You can even get a banjo cap to seal the fittings to avoid having the hoses hooked up and in the way

[SEVEN]

Those work so good. Highly recommended it for pump outs. Used to take turning the pump on 3 times to get everything out. Know, it sucks both tanks dry within minutes. Without it I was sucking air and not waste.

[Boatsb]

Fueling too fast where the vent cannot keep up with the input will blow the tanks apart.

I've never seen a small boat able to take fuel out of a pipe that large.

You need to use a pretty small pump so that you don't blow the tanks up from the vents not being able to pass all that airl

[racclarkson@gmail.com]

Fueling too fast where the vent cannot keep up with the input will blow the tanks apart.I've never seen a small boat able to take fuel out of a pipe that large.You need to use a pretty small pump so that you don't blow the tanks up from the vents not being able to pass all that airl

Right. The gravity feed in fuel line sized lines in a closed feed is safest.