Fuel Hose Layout

[Wideocean7]

Having resigned myself to the fact that I have to replace one of my aluminium diesel tanks (and probably the other a bit down the track), I thought it would be timely to check the hose arrangements (of which I know bugger-all!).

There’s a tank either side of the engine. The current set-up is that fuel is drawn from both tanks (or just one if a valve is closed) via 5/16” hose. Then the fuel goes to the engine via a Filter Boss and Racor filters. Returned fuel goes to both tanks – there are no valves to isolate one or the other tank (which I thought a bit strange). There’s also an equalisation line connected to the bottom of each tank. The rough sketch shows what this looks like.

With heaps of info gleaned from this and other forums and Nigel Calder’s books, my thinking is this:
a) Intall 2 manifolds in an easily accessible position – one to manage the supply and the other for the return. This would enable fuel to be drawn and returned to the same tank, or returned to the other after polishing.
b) Get rid of the equilisation line as many have said it’s a leak risk. I’d replace it with a transfer pump with hoses teed-off the supply lines (with appropriate valves needless to say). I’m not sure yet if this is needed or even a good idea but I thought the option to rebalance the boat might be useful?

I'm a bit in the dark about "best" practices so feedback would be really appreciated.

One last question - where do you get your fuel line fittings? I've hunted high and low here in Australia and all I can find are those from a car parts shop and only in brass.

Thanks All.

[Uncle Bob]

Originally Posted by Wideocean7

Having resigned myself to the fact that I have to replace one of my aluminium diesel tanks (and probably the other a bit down the track), I thought it would be timely to check the hose arrangements (of which I know bugger-all!).

There’s a tank either side of the engine. The current set-up is that fuel is drawn from both tanks (or just one if a valve is closed) via 5/16” hose. Then the fuel goes to the engine via a Filter Boss and Racor filters. Returned fuel goes to both tanks – there are no valves to isolate one or the other tank (which I thought a bit strange). There’s also an equalisation line connected to the bottom of each tank. The rough sketch shows what this looks like.

With heaps of info gleaned from this and other forums and Nigel Calder’s books, my thinking is this:
a) Intall 2 manifolds in an easily accessible position – one to manage the supply and the other for the return. This would enable fuel to be drawn and returned to the same tank, or returned to the other after polishing.
b) Get rid of the equilisation line as many have said it’s a leak risk. I’d replace it with a transfer pump with hoses teed-off the supply lines (with appropriate valves needless to say). I’m not sure yet if this is needed or even a good idea but I thought the option to rebalance the boat might be useful?

I'm a bit in the dark about "best" practices so feedback would be really appreciated.

One last question - where do you get your fuel line fittings? I've hunted high and low here in Australia and all I can find are those from a car parts shop and only in brass.

Thanks All.

For the fittings consider stainless steel, they are available in hose size and various thread size, online and no doubt personal shopping where possible.
Don't know whats available in your location but the stainless shop at Taren Point in Sydney has a good selection.

[Wideocean7]

Thanks for the lead. I’ll check them out.

[stormalong]

By separately selecting the source and return tanks you run the risk of overflowing a tank. If you select to draw on tank A and return to tank B which is already full you will have fuel overflowing out your tank vent into the water.

Two possible design solutions:

Have an equalization hose located near the top of the tank but well below the tank vents.

Have the supply and return valves coupled together so that the supply and return always go to the same tank.

[tenchiki]

I was crewing on a delivery when that happened. The skipper changed the source to the other tank, but didn't change the return. When the return tank filled up, the engine just stopped (on my watch...). At first the skipper thought that the engine ran out of fuel, however after noticing that the source and return were different tanks and switching one of the valves (I forget which one she switched), the engine started right up without needing any bleeding. We figured that the back pressure of the full tank stopped the injector pump.


So it won't _necessarily_ overflow...

[wingssail]

For marine parts in Queensland look at Marine Warehouse and Whitworth's Marine. I think there are others. Brisbane especially and probably Townsville should have marine stores.

For fuel line routing I have the following suggestions:

1. put a racor filter on each tank so if one gets plugged you can select the other while you clean the filter.
2. Use two position valves (starboard and port) for both the feed line to the engine and the return line. Try to be careful that you select both of them or you will have an inadvertent transfer of fuel going on.
3. Remove the equalization line, there is little need for it. Don't plan on moving fuel, just select the one which has fuel in it. If you do wish to transfer fuel that can be accomplished by routing the fuel return to the tank you wish.

[Wideocean7]

Originally Posted by stormalong

By separately selecting the source and return tanks you run the risk of overflowing a tank. If you select to draw on tank A and return to tank B which is already full you will have fuel overflowing out your tank vent into the water.

Two possible design solutions:

Have an equalization hose located near the top of the tank but well below the tank vents.

Have the supply and return valves coupled together so that the supply and return always go to the same tank.

Thanks Stormalong. Point taken about potentially overfilling. I was thinking about a transfer pump from the top of each tank rather than a gravity-fed equalisation hose so that I have control over if/when to transfer. Does this make good or bad sense?

[Wideocean7]

Originally Posted by wingssail

For marine parts in Queensland look at Marine Warehouse and Whitworth's Marine. I think there are others. Brisbane especially and probably Townsville should have marine stores.

For fuel line routing I have the following suggestions:

1. put a racor filter on each tank so if one gets plugged you can select the other while you clean the filter.
2. Use two position valves (starboard and port) for both the feed line to the engine and the return line. Try to be careful that you select both of them or you will have an inadvertent transfer of fuel going on.
3. Remove the equalization line, there is little need for it. Don't plan on moving fuel, just select the one which has fuel in it. If you do wish to transfer fuel that can be accomplished by routing the fuel return to the tank you wish.

Thanks Wingsail. The Filter Boss has 2 Racor's connected to it with one being selected whilst the other is off-line or being cleaned/filter changed. It's in an easily accessible position and I was thinking of placing the valves/manifolds next to it so switching between tanks "should" be straighforward. I've taken on board the overriding views that the same tank should be used for supply and return. The only time I imagined returning to the other tank is if I were polishing new fuel in (say) the starboard tank and returning it to the empty port tank and as you say, the return hose can be selected to do this. I'm now thinking of removing the equilisation line as you suggest and transfer pump. The Filter Boss would do that job anyway I hope?!

[Wideocean7]

Originally Posted by tenchiki

I was crewing on a delivery when that happened. The skipper changed the source to the other tank, but didn't change the return. When the return tank filled up, the engine just stopped (on my watch...). At first the skipper thought that the engine ran out of fuel, however after noticing that the source and return were different tanks and switching one of the valves (I forget which one she switched), the engine started right up without needing any bleeding. We figured that the back pressure of the full tank stopped the injector pump.


So it won't _necessarily_ overflow...

Good example!

[wingssail]

Originally Posted by stormalong

By separately selecting the source and return tanks you run the risk of overflowing a tank. If you select to draw on tank A and return to tank B which is already full you will have fuel overflowing out your tank vent into the water.

Two possible design solutions:

Have an equalization hose located near the top of the tank but well below the tank vents.

Have the supply and return valves coupled together so that the supply and return always go to the same tank.

Stormalomg, I prefer NOT to try to make a system "fool-proof". The fools will find a way to get it wrong.

With the goal of simplicity, and leaving some responsibility on the operator, all we need is for them to understand that both the feed and return valves should be selected to the same tank unless some transfer is desired. If they set them incorrectly the consequences fall on them.

I personally have high expectations for people and they generally live up to them.

[stormalong]

Originally Posted by Wideocean7

Thanks Stormalong. Point taken about potentially overfilling. I was thinking about a transfer pump from the top of each tank rather than a gravity-fed equalisation hose so that I have control over if/when to transfer. Does this make good or bad sense?

Wideocean7: You can do a transfer pump to move fuel but is has to draw from the bottom of the tank. You could "T" off the existing pickup tube and discharge into the return line of the other tank. Here again you need to be careful to not overfill the receiving tank.

IMHO the best solution would be to mechanically link two valves so that the return always goes to the same tank as the draw. Not sure why you want to transfer fuel from one tank to the other unless it is to balance the fuel weight. IMHO Any fuel polishing system should return the fuel to the source tank.

The present equalization connection is a good way to get the load balanced. A valve in the balancing hose makes equalizing optional. I am not a fan of any bottom openings in a fuel tank on a boat but that is a decision you have to make.

BTW if you have to replace one tank and both tanks are the same age why not replace them both now? Why wait until you have a crisis with the other tank and have to scramble to get one made and replaced.

[Bill Seal]

Groco 6 port tank selector valve, switches feed and return together. Sort of expensive ($150) but fool proof.
BTW, What's wrong with your aluminum tanks? I'm replacing my black iron leaker with .125" aluminum and am hoping it will last forever

[wingssail]

Originally Posted by stormalong

...The present equalization connection is a good way to get the load balanced...

No, this is not a good way. Any period of sailing with the boat heeled over will result in all the fuel draining to the leeward side. Yes a valve will prevent that, but better, just delete the equalization link, it is unneeded.

[stormalong]

Originally Posted by Bill Seal

Groco 6 port tank selector valve. Sort of expensive ($150) but fool proof.

Well there you go, and only 1/6th of a boat unit. Considering the cost of dealing with a fuel spill it is a pittance.

[stevead]

If you didn't want to stump up for the Groco 6 port valve, you may want to price just a pair of three way ball valves.

For fittings, in addition to the normal marine suppliers in Australia, you could enquire at Enzed or Pirtek. I personally can recommend Pirtek. Although unrelated to your requirements, I've just cleaned up the hydraulic furling system on my partner's yacht, replacing a badly installed silicone covered hole through the deck for the hydraulic hoses with stainless steel bulkhead union fittings secured to a stainless plate and having the existing hydraulic hoses cut to length with new stainless steel hose tails crimped on.