Putting filler in the bilge- good or bad idea, and what to use

Kelpie

Kelpie

Well-Known Member
Joined
15 May 2005
Messages
7,766
Location
Afloat
Visit site
My boat has a fair bit of rainwater ingress which finds its way into the bilge. The bilge itself has several low spots and does not drain cleanly, so when the pump has done all that it can there is still a fair quantity swilling around down there.
I was wondering about using some sort of lightweight filler, e.g. automotive stuff, to level out the dips and create a single sump. This would mean filling over the tops of the keelbolts so I'm not sure if it's a good idea or not.

Obviously the long term answer is to stop the water getting in, but with a foam sandwich deck that is not as easy as it sounds :(
 
I could imagine some foam glassed in and flowcoated over, to make a more convenient shape to the sump. But covering the keel bolts doesn't seem like a smart move.

Pete
 
prv said:
I could imagine some foam glassed in and flowcoated over, to make a more convenient shape to the sump. But covering the keel bolts doesn't seem like a smart move.

Pete
Click to expand...

It needs to be something cheap enough to fill quite a volume economically, but ideally be easily removable so I could dig out the keelbolts again. Maybe stick upside down yoghurt pots or similar over them to keep them clean, before applying the filler?
 
Apologies if this is a dumb idea but expanding builders foam? Then a fibreglass skim layer? Agree I like to see my keel bolts but until the leaks are sorted?
 
Kelpie said:
My boat has a fair bit of rainwater ingress which finds its way into the bilge. The bilge itself has several low spots and does not drain cleanly, so when the pump has done all that it can there is still a fair quantity swilling around down there.
I was wondering about using some sort of lightweight filler, e.g. automotive stuff, to level out the dips and create a single sump. This would mean filling over the tops of the keelbolts so I'm not sure if it's a good idea or not.

Obviously the long term answer is to stop the water getting in, but with a foam sandwich deck that is not as easy as it sounds :(
Click to expand...

Would you renovate a house with a bad roof? Fix the problem first.
 
It's not an either/or situation. I agree fixing the deck leaks is the ultimate answer but that's a huge job as I expect to end up rebedding every deck fitting.
The boat will be spending this winter afloat and with water in the bilge will never be able to dry out, so there will be damage to the interior. I have obviously removed all furnishings etc already.

Expanding foam would be very easy and very cheap, and very temporary. I'm not convinced that it is suitably closed-cell, without needing some sort of coating over the top.
 
Kelpie said:
The boat will be spending this winter afloat and with water in the bilge will never be able to dry out, so there will be damage to the interior. I have obviously removed all furnishings etc already.
Click to expand...

Are you sure? We usually (always?) have a bit of water left in the bottom of our deep bilge, and have never noticed any adverse effects. (No keelbolt, though - encapsulated keel.) It certainly doesn't damage the interior or make the boat damp. I imagine most of the time it isn't warm enough to cause any significant evaporation, and when it's warm enough to cause any it's because the air is warm enough to hold the moisture (and carry it out of the boat, which is well ventilated).

Our only problem with damp is the result of winter sailing - breathing, cooking, wet oilies below, etc. The boat is damper when we leave it, than when we arrive back a week or few later.
 
How about a cover to to keep the rain off the deck leaks?

TBH it's going to be quicker to take all the fittings off, temporarily seal the holes with RTV, then refit them one by one.
 
Don't fill your keel space with foam or similar. If your GRP is susceptible to so called Osmosis then water trapped between the foam and GRP can cause or accelerate osmosis. Similar examples of this can be found between foam / carpet pads on trailers / cradles where they touch the GRP and inside GRP water tanks. Fresh water can be more problematic than sea water when it comes to causing osmosis which is why the carpet pads can be an issue. The time and effort required to get a clean bilge and good conditions for a water tight bond between the foam and GRP would be better spent eliminating the leaks.

I had a similar problem caused by leaking windows and a leaking cable gland at the stern. I used nappies and sponges poked into inaccessible spaces and retrieved with string to absorb the water. It worked OK until I left a nappy for a long time in the engine sump and it disintegrated causing an almighty mess. There are better products now than nappies for absorbing water.

Once you start removing deck fittings and such like it really is not a big deal and you soon develop tricks to access bolts without ripping out the inside of the boat. It is likely that you will find other issues as you re-bed fittings and obviously this is a good time to fix them.

If I was going to level out a bilge so that it drained better, I would be inclined to do the job with only GRP if it is a large flattish area or faired foam encapsulated in GRP if it is a deep area.
 
BlowingOldBoots said:
Don't fill your keel space with foam or similar. If your GRP is susceptible to so called Osmosis then water trapped between the foam and GRP can cause or accelerate osmosis. Similar examples of this can be found between foam / carpet pads on trailers / cradles where they touch the GRP and inside GRP water tanks. Fresh water can be more problematic than sea water when it comes to causing osmosis which is why the carpet pads can be an issue. The time and effort required to get a clean bilge and good conditions for a water tight bond between the foam and GRP would be better spent eliminating the leaks.

I had a similar problem caused by leaking windows and a leaking cable gland at the stern. I used nappies and sponges poked into inaccessible spaces and retrieved with string to absorb the water. It worked OK until I left a nappy for a long time in the engine sump and it disintegrated causing an almighty mess. There are better products now than nappies for absorbing water.

Once you start removing deck fittings and such like it really is not a big deal and you soon develop tricks to access bolts without ripping out the inside of the boat. It is likely that you will find other issues as you re-bed fittings and obviously this is a good time to fix them.

If I was going to level out a bilge so that it drained better, I would be inclined to do the job with only GRP if it is a large flattish area or faired foam encapsulated in GRP if it is a deep area.
Click to expand...

concur these recommendations, in conjunction with a cover in the short term. I think you will later regret any attempt at reprofiling the floor using filler or foam.

Colin. Www.solocoastalsailing.co.uk
 
If you do consider using a filler (rightly or wrongly over keel bolts? ) please test the filler type first.
Have you ever put a solid cured lump of car body filler (Polyester) in a bucket of water ??? No...... give it a try ..... most Polyester filler types turn to a soft mush if left in a wet environment.
Most Epoxy fillers will serve you well for this job, be careful though their bond is better as well so you may not be able to remove it easily in the future if at all.
You could also consider using epoxy resin by pouring it (after adding hardener and mixing of course) I have seen this done before and lead shot was added to pour into a keel space. If you are going to try epoxy resin you will need a very slow hardener (hours not minutes) usually associated with Laminating resins. SP Ampreg or West Proset.

You should also consider what I thought was a genius idea, I saw it being done on a large yacht......
Lard ..... yes lard....
I saw a pallet delivered once and it was melted and poured into a keel space .. it sets to a solid .... its waterproof .... sticks like the proverbial so water cant get around the edges and is easily removed if needed ( just heat it up )
 
Couldn't agree more with others who advise you to seal the decks, the bilge level is secondary to getting your boat dry as possible, just doesn't make sense to focus on the ease of removing what you should have and can prevent in the first place.
 
I have removed keelbolts in 3 yachts. In all 3 the bolts were fine, the nuts surface corroded only. In all 3 the washers were more corroded than the nuts, and to varying degrees. Generally the washers had been sealed in with fillers and paints, the nuts and bolt heads more exposed. I would not favour filling in around the keelbolts.
 
+1 pampers or equivalent. String or light cotton line fed through garden hose is an excellent way to,wick out small crevices.sit a nappy over the higher end of the hose( with 150mm line protruding).all items in this approach are easily obtainable and cheap.I would cover the boat with cheap tarpaulin as well.
 
Last edited:
You must log in or register to reply here.

Share this page

Top