Fuel stop cock – where?

[BabaYaga]

The diesel tank on my boat never had a stop cock.
I believe it should have, so installing one is on my list of winter projects.
But I can’t quite decide where to put it and would need some advice.
The scene:
The tank is under the ”floorboards” in the sb cockpit locker, with the take off pipe on the tank top. From here, the rubber fuel hose passes through a longitudal bulkhead into the engine compartment.
It makes a small loop, which includes a squeeze bulb, before entering the head of the CAV primary filter (this is placed slightly over the level of the tank top, which explains how I have got by without a stop cock for so many years).
After the CAV filter the fuel hose goes down to the engine, with its lift pump, secondary filter, injection pump etc.

Do I install the stop cock:

1. By the tank, directly after the take off pipe (where it might be very difficult to access in a hurry).

2. In the fuel hose, just where it enters the engine bay.

3. At the intake to the CAV filter head.

4. At the outtake from the CAV filter head.

Any thoughts?

 

[Bobobolinsky]

Outside of the engine bay, between the tank outlet and the tank. If you can't make it accessible, use extension to make the handle easy to turn. Maybe fit a fire extinguisher close by the handle.

 

[Evadne]

I've got two, one under the tank and one in the side locker, before the primary filter. As long as you remember to switch them all to the 'on' position

 

[pyrojames]

I have one at the fuel take off on the tank. It is operated by a remote pull from a cockpit locker. A simple spring loaded valve that is held open on an over centre cam that can be flipped over very easily.

It works, sometimes accidently pulled! :/

 

[KellysEye]

Out of interest we don't have one, why do you want to fit one?

 

[Stork_III]

Out of interest we don't have one, why do you want to fit one?

Engine fire burns through fuel pipe. - no fuel cut off so contents of tank available to burn.

 

[rob2]

The type of dip tube you have relies on either a syphon effect or the lift pump to draw fuel from the tank. If the hose burns through, there will not be a pump to feed the fuel into the fire, but you may still have a syphon (depends on the relative levels of the components). The ideal place for the cock is away from the engine box but easily accesible.

Rob.

 

[prv]

A simple spring loaded valve that is held open on an over centre cam that can be flipped over very easily.

That sounds like a handy device. My fuel shutoff is deep in a lazarette that's not easy to get at from the cockpit, but has a cubbyhole on the other side of the fibreglass that would be ideal for a pull-ring. I've never seen a valve like that though - any identifying name etc to help find it?

Pete

 

[pvb]

I reckon I'd start by changing the fuel pipe from rubber to copper.

 

[Stork_III]

I reckon I'd start by changing the fuel pipe from rubber to copper.

Is your pipe copper from tank to engine with no flexible (rubber) at all?

 

[pvb]

Is your pipe copper from tank to engine with no flexible?

No, it's copper to primary filter though, then copper to a short flexible to the engine.

 

[Ross D]

Engine fire burns through fuel pipe. - no fuel cut off so contents of tank available to burn.

If you have dieso then the fuel pouring onto the fire is more likely to put it out than catch fire, but you would then have a terrible mess to clean up. Fuel stop cocks on above engine tanks are more useful for stopping the fuel pouring out when changing filters etc. Or if your decompression lever/cable or engine stop fails.

In any case I would have it as close to the tank as possible, mounted directly to the tank if possible. That way you have far more of the system isolatable if there are any problems.

I have a bilge mounted tank so no need for a valve, but definitely needed a lift pump. When we bought the boat there wasn't one fitted and the only way of priming the engine was to suck the dieso up the pipe until you had a mouthful.

 

[Latestarter1]

Out of interest we don't have one, why do you want to fit one?

Because you have no need of one.

If your diesel installation is correct, your feed is taken from a standpipe in the top of the fuel tank, stop cocks should always be avoided.

 

[Ross D]

Because you have no need of one.

If your diesel installation is correct, your feed is taken from a standpipe in the top of the fuel tank, stop cocks should always be avoided.

Surely even if your fuel is drawn from a standpipe on top of the tank, if the tank is above the engine, a removed filter or cracked pipe can still set up a siphon and drain your entire tank into the bilge?

 

[BabaYaga]

Thanks all for your replies.
Since the risk of an engine room fire is one of the reasons why I want to have a stop cock, I guess it makes sense to put it on the outside, i.e. on the tank top. I will have to solve accessibility one way or the other.
As already has been pointed out, a leak or crack in the fuel line further down could make the diesel siphon out – in the worst case in combination with a fire.
Also to be able to handle an engine run away/stop solenoid failure makes a stop cock a good idea I think.
Originally I considered a stop cock somewhere by the primary filter, in order to make the bleeding procedure after filter change easier. But the fire scenario is more important.
I don't see why copper pipe should be superior. There is still a lot of rubber hose on the engine itself (lift pump – secondary filter – injector pump).

 

[Latestarter1]

Surely even if your fuel is drawn from a standpipe on top of the tank, if the tank is above the engine, a removed filter or cracked pipe can still set up a siphon and drain your entire tank into the bilge?

I have knocked several vessels on survey for having fuel cocks.

I can assure you that in the event of fire on board the last thing you will be thinking about is diving for a fuel stop cock.

Fitting a fuel cut off can more likely cause an accident. Can think of one occasion when crew member grabbed a line out of the lazarette and knocked the fuel tap to off position. Vessel pushed off with engine running until filter was exhausted, engine stopped leading collision with another vessel in marina.

Keeping life simple on boats keeps them safe. I anybody has a fuel system so cranky that it will likely spring a leak then owners should spend time making system fit for purpose rather than buggering around with fuel taps. Diesel fuel is not a particularly volatile fuel, has very low fire risk.

 

[ksutton]

The most useful and obvious reason for having a tap between the tank outlet and primary filter seems to have not been commented on.
Turn it off before changing the fuel primary filter, saves a whole lot of air bleeding issues.
Fuel shut tap holds the siphon, just a matter of turning it back on and opening the bleed screw on the primary filter after replacing the filter.

 

[Dave_Seager]

The Boat Safety Scheme requires that a fuel cock or valve must be fitted in the fuel feed pipe as close to the tank as possible. The reason given is to prevent loss from the tank if the fuel feed fails. I know that the scheme only applies to certain inland waterways but it can be a useful check-list elsewhere.

If I had a leaky fuel pipe then I would prefer to close a valve rather than have 100 gallons of diesel in my bilges.

 

[Quandary]

As Dave says a fuel cock is required by the B.S.S. operated by B.W. etc. Not only that but they require you to have a visible notice indicating where it is, not easy if it is under a berth cushion. Some of B.W.s rules are aimed at avoiding pollution as much as safety though oddly they still do not demand holding tanks even for liveaboards.

 

[PerformanceSailor]

Our '88 model boat came with a brass ball valve fitted right at the tank outlet. Seems like a good idea, even without the urging of any sort of "standards" requirement.
I temporarily close it when I open up the fuel system to change filters on the Racor or the secondary spin-on filter on the diesel.

A few years ago we replaced all the old copper supply tubing and the hose return with new USCG approved fuel lines. The new standard is a multi-layered material with a fuel-proof liner, and quite sturdy. Good thing there's many feet of line.... you have to read along it for a foot at a time to get through all the codes and standards-met for the certifications!

Kidding aside, it's unlikely ever to soften or collapse like the ancient stuff from decades ago.

Having the tank under a settee would make it relatively safe and easy to shut off the fuel should there ever be any emergency, also.
If the tank was buried aft behind the engine, like on a lot of boats, I'm not so sure what the best answer might be.

PS