Poly Fuel System Config

Gents,

Thanks for the forum, I've already picked up a lot from reading it. Hope I don't ask too many obvious questions.

I'm considering re-tanking my 32' Delta. It's configured as a powertroller in SE AK. It currently has a nightmare of a fuel system, and I just want to gut it and start over. 25 year old steel tanks which appear to be in good condition, but due to the size of the tanks, I can't get to much of them to inspect them, then you have the old copper lines, questionable gate valves, etc. And, it's got enough tanks for 700gal, which is way more than I'll ever need and I want to convert that space into more fish capacity. (it used to have a v8 engine and they wanted to run from Seattle to Sitka without stopping for fuel) When filled, they really squat the stern down, and that leaves me wanting to not keep them filled so I can carry more fish.

So, I've just about decided on (4) Moeller 40gal tanks. 160 gallons will be plenty for this boat and the trips I do. My reasoning is that it'd open up a space so I could actually service all the connections and keep an eye on things. With 40 gallon tanks, the lack of baffles shouldn't be too big of a problem in my opinion, and corrosion won't be an issue anymore. And, if I get a shot of bad fuel from a tender or some remote village, I can yank the tank, clean it, and get back to work.

So my question is: How would you configure the 4 tanks? They will be in the stern of my boat. I have a diesel, so I obviously have a fuel return line. Ease of bleeding is also a priority for me too. If anybody has a schematic for a 4 tank system or some advice, it would be greatly appreciated.

Thanks! FV Adagio

Just thinking aloud: Probably route supply and return lines from each tank to a convenient spot. Then have four valves tied to engine supply, four valves coming from engine return. Open one sup valve and one return valve to the tank you want to use, the rest of the valves closed. You can experiment with running two tanks at once, but that can be tricky as a bubble in a line can divert fuel in ways you don't expect. System should work fine. Just put valves where they are easy to get to.

Welcome to the forum!

A couple of Groco Six Port Fuel Valves might help simplify your installation.
GROCO MARINE PRODUCTS

There are fuel tanks , and there are boxed of fuel.

For a gas boat a box of fuel is fine as the consumption is usually high and the engine doesnt mind a bit of water in the fuel.mIGHT STUMBLE A BIT BUT NOT STOP.

Diesels get unhappy with water in the fuel , SO THE FUEL MUST BE DE WATERED.

This is usually done with filters , but the filters fail Big Time if you get a batch of poor fuel, or a deck fill leaks.

Another solution is a day tank, where only the cleanest fuel is used to fill it.

The S&S tank is not off the shelf , but in a remote area at least one of the tanks should have a real sump you can drain the water from.

Remember polly tank installation is a 2 step procedure . The tank must be filled with fuel for a day or two to expand before you foam it in place.


Perhaps just a custom day tank?

Yacht Design - Type Plans - Sparkman & Stephens

www.sparkmanstephens.com/yachtdesign/design_typeplans/‎

If fuel tank replacement is absolutely necessary has anyone ever priced these bladder tanks?

Marine Fuel Bladders and Auxiliary Fuel Tanks

I say a video once where they replaced the bladders tanks in a C-117 through a 16" or so port.. they had a small guy crawl inside the bladder through the hole to aid fitment.. looked a touch creepy

HOLLYWOOD

Hollywood, I've never used one of their tank liners but I did sell their on deck bladder tanks back in the seventies and eighties. ATL makes a first class product and if they say it works, I believe them.