The curse of the mystery bilge water

[alexincornwall]

Hi all,

I’m a new poster to the forum but have been trawling the wealth of very informative content here for a few weeks. My issue has been covered in various guises, but I’m really struggling with this one and hoping that somebody might be able to give me a helpful steer.

The bilges of our Dufour 32 have always been bone dry i.e. you could blow dust around them, not a drop of moisture. This changed a couple of weeks ago when I motored out of the marina and realised that we had lost our speed log. Presuming the impeller had developed a layer of gunge, I whipped out and plugged in whilst underway. In hindsight, I probably would avoid doing so whilst underway as the water ingress was substantial when compared to removing on the pontoon. I probably took in a litre or two, plugged the fitting, cleaned up the impeller (now working perfectly), and continued our short journey. I did a quick but by no means thorough drying up job and left the boat for one week. When I next returned, I was surprised to see that the bilges now contained the best part of 4-5 litres of (salt) water. Not enough to activate the bilge pump but enough for concern.

Presuming that I must have incorrectly refitted the impeller at sea (and that it was now letting in a little water), I very carefully removed it again, re-greasing all of the seals whilst taking extra care when replacing. I painstakingly pumped the bilges completely dry and noted zero ingress through the impeller fitting.

Returning two days later to check, the fibre glass around the impeller is bone dry, but I now have a couple of mug’s worth of salty bilge water around the keel bolts. The hull bilge is made up of a kind of matrix system and I am confused that the ‘compartments’ fore of the keel bolts but aft of the log impeller are completely dry. The water exists only in the keel bolt compartment containing the keel bolts. The keel bolts were recently replaced and the boat has certainly not run aground so I have ruled out the possibility of damaged/leaking bolts. It just seems too coincidental that the bilges had been historically completely dry up until the log impeller clean up. My only thought is that there may have been excess of bilge water that had been trapped (meaning I was unable to dry up), which has now settled in the lowest compartment of the bilge.

I appreciate that boats might take on a little water, but given the boats history of dry bilges, this is driving me nuts! Thanks in advance for any advice.

 

[Pye_End]

Probably worth focusing on the impeller first because of timing. If it is possible, build a dam out of bluetack or butyle tape or something. If not, maybe put toilet paper or talc down to make it more obvious. I have had similar which turned out to be the O rings on the impeller needed changing.

 

[RichardS]

The bilge compartments usually seem to be connected with little holes so water does tend to find its way around eventually.

I suspect that there is no problem but that you need to continue the drying out process with old towels or such like until you really have all the water out. You could always leave some kitchen roll or similar around the log fitting and see if that picks up any moisture but if its been well greased with silicone grease or whatever and rebuilt correctly I'm sure it will be fine.

Welcome to the Forum.

Richard

 

[sarabande]

I wonder if the admission of a lot of water from the speed sensor has freed up the limber holes and you are now getting water to the keel bolt area from another part of the bilges.

Do you have another bilge pump further for'd than the main one ?

 

[wotayottie]

As the others have said, my first thought would be flow through the limber holes from the impellor removal. Doing that under way with the boat moving around could mean water getting lodged in strange places before slowly draining into the bilge

That said, coincidences do happen. Dry up the water and wait a week or two. In the past with similar issues I have dusted talcum powder around suspected areas so that any water flow would leave a telltale track. Helps tracing leaks.

 

[duncan99210]

It's almost certainly water that came in when you had the fun with the log, which has worked its way into the 'matrix' now emerging from the limber holes in its own sweet time. Whenever we get a bit of water in the bilge, it can take a week or more mopping up small quantities as it trickles down to the lowest part of the bilge. Than, just when you think you've got the lot, you'll have a cracking sail on a tack you've not used since the water arrived and you'll discover yet another little trickle emerges. Really is nothing to worry about, especially as you're happy that the log isn't leaking.

 

[jac]

It's almost certainly water that came in when you had the fun with the log, which has worked its way into the 'matrix' now emerging from the limber holes in its own sweet time. Whenever we get a bit of water in the bilge, it can take a week or more mopping up small quantities as it trickles down to the lowest part of the bilge. Than, just when you think you've got the lot, you'll have a cracking sail on a tack you've not used since the water arrived and you'll discover yet another little trickle emerges. Really is nothing to worry about, especially as you're happy that the log isn't leaking.

Agreed.

I decided to wash mine out last year when she was ashore. A week later the sump was basically full again from all the very slow "draining" via the limber holes. Mine was slow as there was no gentle movement which might speed it up a little. water will collect in all sort of places and remain there until it can get to one of the limber holes. if they are mil or two above the bottom of section of bilge they are in, then that's a a mil deep puddle which goes nowhere until the boat pitches a little and it goes through.

 

[bobgarrett]

If you only pumped your bilges dry then there will be some water left in the bilge pump pipes that trickles back down slowly after you finish pumping.

 

[Simondjuk]

As already said, it can take a long time for the residue of a reasonable amount of water in the bilges to find its way out of the matrix and hidden corners.

I know this having once decided to give my bilges a thorough wash to get rid off all the dust and having to mop up little puddles that formed here and there for a couple of weeks afterwards.

What was surprising was the amount of rubbish that half flooding the bilges washed out of the hidden places - sweet wrappers, cable tie trimmings, bits of wood from holes drilled during the build of the boat, bits of GRP from the same source, a small plastic screw cap and all sorts of clumps of dust and hair.

On the upside, given the bits left over from the manufacturing process that were washed out, it offered reassurance that the boat had never been in any way substantially wet inside previously.

 

[EdWingfield]

Stern gland? In the marina run the engine in drive and check.

 

[alexincornwall]

Thanks everybody for their considered and reassuring responses. I agree (and hope) that this is likely to be a by-product of the impeller lifting so will follow the mopping up instructions as suggested. I took a look again yesterday evening and things seem to be settling down though still a small about of water visible in the aforementioned area. The limber holes actually seem to be holding a little water themselves as they have obviously been drilled a little lower than the main bilge compartment levels. I have also found a larger pool of water just aft of the impeller fitting that I cannot manually get to and doesn’t seem to want to move with the boat on the pontoon, hopefully a breezy sail this weekend will dislodge that. If the problem persists then I will move to the testing methods suggested.

No other bilge pump in front of the main unit. I am almost certain that the stern gland and engine water cooling system are fine as that area of the hull is also bone dry.

 

[jordanbasset]

Having spilled a load of water in my old boat have found if you roll up something akin to a jay cloth and stick it in the hole or holes , so you wick it out, it will speed the process up.

 

[PeterR]

I suspect the lay up of the 32 is very similar to the 34. On my 34 water from both fore and aft always finds its way via the limber holes and fore and aft beams to the beam just forward of the aft keel bolt. You have to be sinking for any to get near the bilge pump. The water in the beam then leaks out into the section around the aft keel bolt. If you just mop up water in that section it will keep getting wet for ages. My solution is to use a medical syringe with a bit of tubing fitted to syringe out water from the beam via the limber holes. The residual moisture can be removed by rolling up a bit of paper towel and leaving it half in and out of the limber holes. This will wick the water out. Only when you have got those bits of paper perfectly dry and then getting wet again would I worry about having a new water leak.

 

[alexincornwall]

Hi Peter,

As you say, suspect that your bilge lay out is very similar to mine. I had a good windy sail last weekend, which seems to have dislodged the remainder of the water. I have now eliminated the potential of a leak through the speed log impeller or anywhere else, so that has put my mind at rest. Only a little water remaining now having followed all of the advice here!

 

[maby]

We've been having very similar problems with a five year old Beneteau - real pain in the neck and can be very difficult to diagnose. We have had Beneteau engineers crawling all over it without success - due to be lifted sometime in the next couple of weeks for them to take a look underneath. Hope yours proves easier to diagnose.