Rainwater ingress into fuel tank

[Plomong]

Had a serious Senior Moment last Saturday: I inadvertently left the fuel deck-filler cap loose, about two turns, and went to bed. The cap was in place and partially but not fully screwed in. Of course it rained overnight, but I don´t know how heavily -- Plomong sleeps well!!!!

Problem: There must now be some rainwater in the fuel tank. So, which do you recommend:

a) Have the fuel scrubbed by a professional. Seems too drastic.
b) Add a water disperser agent to the tank and hope that is enough.
c) Do nothing and hope for the best, maybe draining the filter on arrival in Brest. Hopefully, the boats movement will keep what little water got in in suspension ??? Or is this too trusting ???

I should add:
1) I´ll be adding a further 20 liters to the tank (65 liters capacity) before departure.
2) There is a Volvo Penta metal (white + grey) fuel filter in the fuel line, with drain screw underneath, but in an impossible location. Access to the screw requires dismantling the stern cabin, almost !!!

So, what is the forum´s advice on this matter ??

Does anyone know how much rain fell in Newlyn / Penzance between 8 pm Saturday and 10 am Sunday ???

Many questions, I know, but the forum has come up trumps many times in the past, so will await impatiently your comments and experiences.

Plomong

 

[Lee_Shaw]

Could you not drain any water off from the jam jar regularly, and put in loads of extra diesel?

 

[Plomong]

Could you not drain any water off from the jam jar regularly, and put in loads of extra diesel?

There is no jam jar, just an inaccessible metal filter, designed for purging in port, and to be done by a contortionist. A glass bowl type of filter would make it easy to check for water, but I don't have that type of filter.

Plomong

 

[pvb]

Had a serious Senior Moment last Saturday: I inadvertently left the fuel deck-filler cap loose, about two turns, and went to bed. The cap was in place and partially but not fully screwed in. Of course it rained overnight, but I don´t know how heavily -- Plomong sleeps well!!!!

I really can't imagine there'd have been much water get in to the tank. It's unlikely to be worth worrying about.

 

[fastjedi]

Lots of questions .....
- How much rain fell?
- Does the area around the filler flood? (manufacturers do put fillers in stupid places)
- Where is the fuel pick up in the tank?

Unfortunately, the only way to be sure its to empty or clean the fuel in the tank.
You don't need any of us to tell you about the consequencies
- Stopped engine / recovery
- Will probably damage the injectors
- If you are unlucky, damaged high pressure pump / head gasket
You could drain 5 litres from the tank, see what you get ..... still doesn't garrantee no water in the bottom.

We had a cheap pressed filler/plastic cap on our last boat. When tightening it sometimes jumped thread. I arrived at the boat one weekend to find the cap loose. I wish I had assumed the worst and emptied the tank. It would have been much simpler!

 

[Plomong]

- How much rain fell?

Not sure, as slept through the night.

- Does the area around the filler flood?

No, the filler is a raised flange about 5 or more mm up off the deck.

- Where is the fuel pick up in the tank?

Looks like it is a simple dip pipe that comes out the top of the tank. It is definitely not a pipe connected to the lowest point of the tank. Beneteau manual clearly warns that the 65 liters capacity is the full tank, but only about 50+ is useable.

You could drain 5 litres from the tank, see what you get ..... still doesn't garrantee no water in the bottom.

No drain tap on this tank. It sits in beside the rudder post, sitting on a bearer built in to the hull, so no space underneath for a sump or a drain tap. In fact, it would be quite a job to remove the tank, if that ever became necessary.

Plomong

 

[srp]

Use a Pela vacuum pump to suck out whatever is in the bottom of the tank, preferably into a clear container (big mineral water bottle??). You can then visually check for water. If you've got one of these you can pour it straight back in the tank, removing anything horrible as you go:


edit - if you have a 'sump' in the tank, or can heel the boat to encourage any water to a low point, you may be a bit more confident that the inlet pipe of the Pela is actually going to pick up any water there may be. If you haven't got a Pela pump, this is your opportunity to justify buying one - incredibly useful for all sorts of jobs.

 

[Spyro]

I doubt if very much rainwater would get in if only 2 turns undone. Even if you left it completely off how much rain would you get in? If there was an inch of rain the volume would only be equal to the area of the filler hole X 1 inch. Hardly enough to leave 1/2 inch in a water/fuel seperator bowl.
I think you are worrying too much you will probably have more in there from condensation.

For peace of mind run the engine for a few hours then drain the filter.
On second thoughts if the outlet is not on the bottom of the tank then you won't get any water getting out.

 

[Cloven]

I had a similar problem some years ago when the neoprene seal on my filler cap split and rainwater got in over the winter.

First trip of the next season and after about 2hrs running the engine stopped. CAV water separator was full of water and obviously the whole fuel system.

Call to coastguard & they requesed another boat to tow us in to fortunately our home marina. Local mechanic pumped out the tank and then purged the whole system. Up and running again in a few hours and no damage done to the engine but could have been a whole lot worse.

Fortunately my fuel tank has a pretty big access hole so I was able to really clean out all traces of contaminated fuel after the initial pump out.

Hopefully yours will not be as bad but suggest you keep a very close eye on the water separator and if you find water collecting then I suggest you will have to do the same as I had to do.

Good luck.

 

[Plomong]

I had a similar problem some years ago when the neoprene seal on my filler cap split and rainwater got in over the winter.

First trip of the next season and after about 2hrs running the engine stopped. CAV water separator was full of water and obviously the whole fuel system.

Call to coastguard & they requesed another boat to tow us in to fortunately our home marina. Local mechanic pumped out the tank and then purged the whole system. Up and running again in a few hours and no damage done to the engine but could have been a whole lot worse.

Fortunately my fuel tank has a pretty big access hole so I was able to really clean out all traces of contaminated fuel after the initial pump out.

Hopefully yours will not be as bad but suggest you keep a very close eye on the water separator and if you find water collecting then I suggest you will have to do the same as I had to do.

Good luck.

Good luck is what I´ll need, crossing from Newlyn to Brest. Will need the motor going down the Chenal du Four and into the marina in Brest. Otherwise hope to sail all the way. Will keep my fingers crossed, and hope that all goes well.

In Brest I´ll check the filter for water once I arrive.

Will check how to drain some fuel out of it tomorrow, just in case I need to use the motor for a longer period, and so need to check the filter contents under way. Saw today the drain screw, but access requires "dismantling" the stern berth, used daily in port, but not underway, so can dismantle it before departure.

Thanks,

Plomong

 

[bammylovechops]

b) Add a water disperser agent to the tank and hope that is enough.

Plomong[/QUOTE]

Buy a bottle ot Wynnes dry fuel, it will do no harm, helped us with no adverse problems, available at most car spares, weigh up the cost if you choose to do nothing, never mind how much time you will lose in the reminder of this wonderful summer!!!

 

[Plomong]

I really can't imagine there'd have been much water get in to the tank. It's unlikely to be worth worrying about.

You're probably right in that, but just in case I'll add some Wynns Dry Fuel to the tank tomorrow, as recommended by bammylovechops, above.

Plomong

 

[Plomong]

You're probably right in that, but just in case I'll add some Wynns Dry Fuel to the tank tomorrow, as recommended by bammylovechops, above.

Plomong

Have decided to bight the bullet and take a sample from the lowest part of the tank, which has a sloping bottom to match the slope of the hull. Tried to take it today using a loaned Pela oil extractor but the plastic pipe just didn't reach the fuel, and anyway would never have reached the lower corner of the tank because the filler pipe enters the tank horizontally just above the deepest point in the tank.

Tomorrow a yard technician will remove the fuel level sensor and take the sample through that orifice. If no water, the Wynns I have already added may already have done its work, or may have been unnecessary. If water is present, will have to clean the tank, no ifs, ands or buts. Just hoping it is the former.

Thanks to all for their contributions, opinions and ideas.

Plomong

 

[Heckler]

Not sure, as slept through the night.



No, the filler is a raised flange about 5 or more mm up off the deck.



Looks like it is a simple dip pipe that comes out the top of the tank. It is definitely not a pipe connected to the lowest point of the tank. Beneteau manual clearly warns that the 65 liters capacity is the full tank, but only about 50+ is useable.



No drain tap on this tank. It sits in beside the rudder post, sitting on a bearer built in to the hull, so no space underneath for a sump or a drain tap. In fact, it would be quite a job to remove the tank, if that ever became necessary.

Plomong

On both my Benes it is possible to undo 6 screws on the fuel level sensor, then you can wriggle the float switch out leaving a 2" plus hole. You can then get a small torch in to the hole, along with a Pela oil sucker tube and suck out any water or crud from the bottom.
I did this on my 351 to chase a small amount of crud. Quite easy really. I doubt whether any water has gone in if your filler is the same as mine on both. They were both at an angle on the sugar scoop edge so any water would just run past!
Stu

 

[Ardenfour]

Not much help, but it all sounds a pretty scandalous design - filters you can't access, tanks you can't reach to clean, check or drain...

 

[NormanS]

It's so much better if fuel tanks are fitted with sumps and drain valves.

 

[Plomong]

On both my Benes it is possible to undo 6 screws on the fuel level sensor, then you can wriggle the float switch out leaving a 2" plus hole. You can then get a small torch in to the hole, along with a Pela oil sucker tube and suck out any water or crud from the bottom.
I did this on my 351 to chase a small amount of crud. Quite easy really./QUOTE]

Good to know that what I have asked to have done tomorrow is really possible. From my examination today, it looked possible, now I know it is, thanks.

I doubt whether any water has gone in if your filler is the same as mine on both. They were both at an angle on the sugar scoop edge so any water would just run past!

Not on the 323. The filler is on the horizontal part of the deck just aft of the stern cleat. The only saving grace its got is that it stands proud about 6 mm or so. However, the weather last Saturday night was quite squally, and showery, so any water running aft along the side deck could have been diverted towards the filler each time the boat heeled in a gust. That is my primary cause for worry -- that running water may have sloshed up on the filler plate and then into the hole. Will know tomorrow if my worries are just that, or are justified. Prefer to be sure rather than start the cross-channel leg and run into trouble that could have been sorted in port before leaving.

Thanks for your info.

Plomong

 

[Plomong]

It's so much better if fuel tanks are fitted with sumps and drain valves.

I agree. My previous boat, a First 285, had a tank vertically under the filler so it was quite easy to sample fuel, see the liquid level by sighting down the filler, and drain through the fuel take-off for the motor, which was from the sump at the lowest point in the tank, with a fuel shutoff valve just under the tank. To drain the tank was simple: close valve, take off pipe, connect short length of pipe leading to fuel carrier, open valve to drain. Simple.

Modern designs probably fulfill the RCD and associated standards and criteria, but that just shows how inadequate those standards and criteria are. Just think of the 5-year life specified for seacocks. Who on earth thought up that jem ??? Probably some nincompoop who wouldn't know a seacock from a hen.

Plomong

 

[BrendanS]

Had a serious Senior Moment last Saturday: I inadvertently left the fuel deck-filler cap loose, about two turns, and went to bed. The cap was in place and partially but not fully screwed in. Of course it rained overnight, but I don´t know how heavily -- Plomong sleeps well!!!!

Problem: There must now be some rainwater in the fuel tank.

This may be a silly question, but if the cap was on, even if not fully screwed home, why do you suspect there will be water in the tank? No rain will have gone down directly - does water pool around/above the filler cap normally?

 

[Plomong]

This may be a silly question, but if the cap was on, even if not fully screwed home, why do you suspect there will be water in the tank? No rain will have gone down directly - does water pool around/above the filler cap normally?

Water runs down the side deck from the forward part of the boat, passing the filler on the way. When heeled to port, and with gusts as we had last Sunday, there is a possibility that the water running past could swill around and ride up on the filler plate. But that would only happen if the quantity of water flowing was significant, hence my other post about rainfall records for the relevant period.

When I finally closed the filler there was a distinct and quite sizeable "bubble" of rainwater on the filler plate just beside the hole, and another on the cap itself. That's what prompted me to think that some may have entered the tank.

Plomong