1 fill hose - 2 tanks?

[andreas.mehlin]

Im about to install to new fuel tanks. Question is, is there any problem having a T or Y connection splitting up the fill hose to the tanks? Should I have a valve to control it or will it be ok when when is full it still finds it way to the other tank? Of course dont wanna have any leaks but I guess the won't be much of pressure when one tank is full cause the fuel is finding the way with the least resistance. Right?

[jamhass]

Having separate fills minimizes the problem of fuel contamination. With only 1 fill, any contamination (fill with water for example) contaminates both tanks. With 2 fills, maybe you realize the error in time. What happens if a single deck fill leaks water in rough seas?

[TheOffice]

My Hylas has 1 fill for 2 tanks. But Jamhass makes a good point.

[andreas.mehlin]

Yes...Good point but there is no way I could run 2 hoses....1 was gard enough

[Cheechako]

I had one boat that way. The bronze Y was well above the tank tops, I doubt there would have been much contamination at all between tanks.
IIRC that system was a bit prone to burping back a lot when filling though, but who knows if that was the reason.

Valves will restrict filling quite a bit unless you oversize them to have 1.5" INSIDE opening with adaptors. Most boats are hard enough to fill....

[captmikem]

On large yachts and ships the fuel inlet port(s) go to a manifold which you can then open the valve(s) to the tank(s) you wish to fill. This works well.
What you are talking about is a simple two outlet port manifold. It should be no problem as long as the hoses and vents are large enough.

M

[Squanderbucks]

If this is a diesel boat. Why not build in a crossover pipe at the bottom of the tanks tith a shutoff valve That way you can fill one tank or both. Also if you open the valve it levels both tanks. To fill just open the valve and fill the fuel will fill both tanks equally. Uses a large 1-1/2” crossover pipe/hose to keep up with the flow.
If you really wanted to be fancy or have an additional feature use a couple of three way valves and you could close the shutoff valve and open one or both of the three ways and drain or flush the tank if ever needed.

[Scorpius]

Mine has been like that since 1988 with no problems. In order to avoid contaminated fuel in one tank vs. the other (assuming you have separate fillers or valves) you would have to fill each tank at a separate fuel dock - not very practical or convenient. Since I started using a Baja filter in 1990 (bought from DownWind Marine in San Diego after getting contaminated fuel there) I've never had a fuel problem. You can watch for crap accumulating in the filter as you are refueling and stop if it is bad. It certainly slows the refueling process but heck, I'm a sailboat! I still take less time to fill at the fuel dock than the average power boat.

I also use biocide religiously when laying Scorpius up for the winter.

[Kd9truck]

I would put a gated Y in, leave 1 tank empty but for when you go off shore

[thunderhoof]

Presumably, you have a single line to your engine from your tanks. If you adopt the suggestion of Squanderbucks to have a valved crossover and the engine feed is from the same tank as the fill line then you can run from a single tank most of the time, keeping fuel fresher. The offside will need to have some fuel with biocide to prevent growth in the tank.
I prefer the idea of having separate lines from each tank to a selector valve before your primary fuel filter. If you fill both tanks and then close the crossover you will have a reserve system such that whenever tank A is low you will have an easy switch over to a full Tank B.