Water in the diesel tank

[geem]

I agree. I have had 4 boats, of which 3 are regarded as quality boats and only one (a Moody 31)had a drain cock in the bottom of the fuel tank. It is incredible that such a low cost necessity is not fitted in all boats

My boat is regarded as quality, (certainly by me). It has a 100 gallon fuel tank made of GRP as part of the original construction 33 years ago. The tank sits directly over the keel and is complete with a 600mm diameter access lid. There is no drain as the drain would need to be into the sea!
I used a hand pump on the end if a copper pipe last weekend to drain water from the bottom of the tank. I got a gallon of water out! I drained 26 gallons of diesel out of the tank but ran out of containers. More containers needed. The plan is to drain then remove the access lid, climb in and fully clean the tank. I appear to have spare pick up pipes for an old diesel heater installation so I am thinking about using these for a permanent fuel polishing set up that would only run when I have the main engine operating. I could also make it switchable so I could run whilst on shore power. Does anybody know of a suitable filter setup with pressure gauge that wouldn't be cost prohibitive? The Perkins engine pre-filter has water sensing and alarm so this is helpful but it doesn't remove the problem.

 

[wully1]

See Superheat6's post on the first page. Maybe you could plumb in something similar?

 

[geem]

See Superheat6's post on the first page. Maybe you could plumb in something similar?

I guess I could use a similar filter unit but would need to install pressure gauges either side of filter head to provide differential pressure.

 

[fisherman]

I'm fitting new tanks soon, there will be, as now, a 4in deck plate, the filler a 2in stopend on a pipe tail under it, so no connection from deck to fuel. If you worry about spills fit a tray round the filler, mop it out.

 

[Leighb]

If you really mean climb in - I can't quite visualise the size - be very careful about breathing residual diesel vapour, confined spaces can be deadly.

 

[DieselPolisher]

You could hire a polishing system to remove the water. Depending on the flow rate of the polishing system not all the water will be removed and so using a biocide will ensure no more bug growth after.

 

[William_H]

Alll sorts of ideas come to mind for this water in the fuel problem. Obviously a deck filler which lets in sea water or rain water needs to be fixed. However you will always get water in the fuel. Either form condensation or from the supplier. The fuel sitting still in your tank over a period of time should allow water to settle to the bottom. Ideally this can be taken off by a drain in a low point cup under the tank. If this is not possible then a pump pick up to the lowest point would be next best thing. It is essential to get the water out before it gets into your engine or breeds bugs.
Many large fuel tanks in installations (underground) will have floating pick up for fuel removal. This means you can't get water until you are near empty. An alternative for a boat might be a fuel pick up well off the bottom. Then have a change over valve to go to a pick up near the bottom for occasions when you want to use the last of the fuel. You would have to change over to the lower pick up before the top ran dry. (requiring bleeding). I think a water drain regularly drained is the best approach. good luck olewill

 

[geem]

If you really mean climb in - I can't quite visualise the size - be very careful about breathing residual diesel vapour, confined spaces can be deadly.

Tank is equivalent to two fifty gallon oil drums so should be able to climb in. I am likely to have to as I won't be able to reach the bottom without climbing in. Thanks for the reminder about fumes.
Anybody got any recommendations for what to clean the tank with? Is it best to just use a detergent like washing up liquid? It seems to work well when you spill a bit of diesel in the sea!