Draining tank?

[stu9000]

Hi

On my last visit to the boat I was a bit over zealous switching off stop cocks. On my return I found an inch of water in the cockpit. I had closed the self draining.

No biggie.
But the diesel tank filler cap is mounted on the floor. Water level seemed exactly to lip of fuel inlet. So I'm a bit suspicious water may have got in.

I ran the engine OK, but just on the mooring.

As the boat is new to me I am tempted to drain the tank siphoning out using garden hose. I have dosed it and have no reason to assume there is a bug. Also previous owner seemed proactive at maintenance. The boat is a Westerly Seahawk so fuel tank is above engine. So probably easy to siphon.

The alternative is to drain off from the bottom. I'm not sure there is a tap low enough.

As it is easy to do I think I'll siphon. Any suggestions on how and what I can do to clean tank or filter the drained fuel?

Thanks

S

 

[Mistroma]

Any water will be in the bottom of the tank and normal off take will be clear of the tank bottom. Running the engine will only pull out water if there's a lot in the tank or boat is moving around a lot. You do need to check if there is water in the bottom of the tank.

Easy if the tank has a sump and drain cock but most don't. You can get access via an existing inspection port or by removing the fuel level sender. Use a siphon or pump with a hose down to the lowest point in the tank as that's where the water and any crud will be sitting. I pump mine out twice every year just to check for contamination and it is a quick job. You will obviously need to take care in resealing the access point and not strip any threads, especially with a plastic tank.

Using a garden hose through the filler might be the next option if you can't open an access point. The main problem is ensuring that the hose goes right to the lowest point. Not too difficult with a filler point right on top of a small tank without baffles. My boat has a couple of metres of hose, enters from the side and tank has a baffle in the middle.

No need to take out much if the first litre from the tank bottom is clear. But you must be certain that the hose is right at the lowest point in the tank.

I'd also suggest checking the seal on your tank filler. I always take precautions to keep it sealed, especially at end of season. I grease the o-ring with enough excess to squeeze some out the top when tightening and that should keep out water, assuming you have a similar design of filler.

 

[lw395]

I'd use my Pela oil extractor to pick up any water from the bottom of the tank.
On our boat, the bottom of the tank is pretty flat so heeling the boat shouldsend any water to the low side.
If you take out a few litres and leave it to settle (I use Polyethylene milk bottles) you should see where you stand.

But what have you dosed it with?
Will it make the diesel absorb lots of water?

 

[NormanS]

Don't run the engine until you've made sure. Best if you have a drain on the bottom of the tank, but if not, syphoning will be fine. Static water and diesel don't mix, so once you're sure that you've got rid of any water, you'll be fine.

 

[stu9000]

Thanks.
This all makes sense.
It will be interesting to see what comes out tomorrow.