JamesS
Well-Known Member
Has anyone a recommendation to fill the join between the cast iron keel and fibreglass hull to get a smooth finish?
Many thanks
Many thanks
Filler for keel joint - help required
- Thread starter JamesS
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vyv_cox
Well-Known Member
It is worth doing a search on this - I know I have responded to this question previously.
Assess what you are trying to achieve. Don't forget that when you see the boat ashore the joint is being compressed by the weight of the hull and contents, but afloat the joint is under tension. The hull will flex a little, opening the joint. Sailing on a hard beat will open it a lot more. No filler on earth will hold the joint together.
If the intention is to prevent water leakage to the keel bolts then the only way is to loosen the bolts, lift the hull, clean thoroughly and apply a suitable grade of an adhesive/sealant, Sikaflex being one manufacturer but there are others. If you put on sufficient that the exess extrudes out of the joint you can spread it all over the outside to give a total width of about 1 inch across the join. There is some hope that this will hold. If you can bolt up and then lift the whole boat while the sealant sets there is a very good chance that it will remain in place almost indefinitely.
If you just want to make it look nice for the fish, then I suggest that you will be wasting your time and money.
Assess what you are trying to achieve. Don't forget that when you see the boat ashore the joint is being compressed by the weight of the hull and contents, but afloat the joint is under tension. The hull will flex a little, opening the joint. Sailing on a hard beat will open it a lot more. No filler on earth will hold the joint together.
If the intention is to prevent water leakage to the keel bolts then the only way is to loosen the bolts, lift the hull, clean thoroughly and apply a suitable grade of an adhesive/sealant, Sikaflex being one manufacturer but there are others. If you put on sufficient that the exess extrudes out of the joint you can spread it all over the outside to give a total width of about 1 inch across the join. There is some hope that this will hold. If you can bolt up and then lift the whole boat while the sealant sets there is a very good chance that it will remain in place almost indefinitely.
If you just want to make it look nice for the fish, then I suggest that you will be wasting your time and money.
Jacket
Well-Known Member
Not sure I quite agree. If your problem is water leakage, and your boat has a flexible bottom like mine, you will always have problems with leakage. Following Vyv's advice will stop the leakage, but only for 6 months or so. Unless you've got far more money than you know what to do with, vyv's advise is impractical, as you'd have to have the boat out the water twice a year, and the time and expense of lifting it off its keel is impractical.
I've found that just drying the boat out along side, scraping of any filler that is accessible, and then squirting in lots of good quality sealant like Sikaflex seals the leak for 3 or 4 months, at a fraction of the cost and time commitment. A bit of a bodge, I know, but at least it lets you spend more time sailing.
I've found that just drying the boat out along side, scraping of any filler that is accessible, and then squirting in lots of good quality sealant like Sikaflex seals the leak for 3 or 4 months, at a fraction of the cost and time commitment. A bit of a bodge, I know, but at least it lets you spend more time sailing.
30boat
N/A
I would look for the reason why it needs fairing first.In my vue if the keel moves enough for the filler/sealant to be displaced then there may be a structural problem.Fiberglass is a flexible material but should not be allowed to flex because it will fatigue after a number of cycles.
My previous boat had a very flexible bottom and there was cracking of the laminate at some points around the keel joint.It took some very extensive grinding and reinforcing to correct the problem.I think that the ideal situation is when there is no perceptible movement at the keel joint even under load.This can be verified by fairing the joint with a rigid filler like epoxy. If it stays in place after some rough sailing then all is well.
My previous boat had a very flexible bottom and there was cracking of the laminate at some points around the keel joint.It took some very extensive grinding and reinforcing to correct the problem.I think that the ideal situation is when there is no perceptible movement at the keel joint even under load.This can be verified by fairing the joint with a rigid filler like epoxy. If it stays in place after some rough sailing then all is well.
I
Iota
Guest
If you are just wanting to smooth the joint rather than anything structural or seepage then gelcoat filler is adequate if anything else then the posts already here seem good advice. Is this on a racing machine?
richardandtracy
Well-Known Member
Try Sikaflex 221. Make sure you clean properly before application.
Regards
Richard
Regards
Richard
vyv_cox
Well-Known Member
I agree that doing this job twice per year would be ridiculous.
My GK29, like all the others, was a little light around the keel attachment point to the hull. In the slings the gap between hull and keel was several millimetres. Rebedding was done professionally as an insurance job after the boat ran itself aground when the mooring failed. The joint always leaked a little afterwards. When beating in seas there would be a puddle of rusty water in the bilges. I then rebedded it myself using the technique described previously and it never leaked again.
My GK29, like all the others, was a little light around the keel attachment point to the hull. In the slings the gap between hull and keel was several millimetres. Rebedding was done professionally as an insurance job after the boat ran itself aground when the mooring failed. The joint always leaked a little afterwards. When beating in seas there would be a puddle of rusty water in the bilges. I then rebedded it myself using the technique described previously and it never leaked again.
G
Guest
Guest
If your concern is cosmetic - forget it
Mine is an HR42. Each time she is lifted there is a 1-2mm gap at the forward end - been there since new. No amount of rebedding/tightening keel bolts has reduced it.
Assuming that your concern is cosmetic rather than leakage, theres no point in filling with normal filler cos as Vyv has said, it will crack. I eventually had the yard use some "flexible" filler, which I think was Silkaflex. This is fine save that Antifoul now cracks along that line.
Life is too short
<P ID="edit"><FONT SIZE=-1>Edited by dcaukill on 03/10/2002 13:35 (server time).</FONT></P>
Mine is an HR42. Each time she is lifted there is a 1-2mm gap at the forward end - been there since new. No amount of rebedding/tightening keel bolts has reduced it.
Assuming that your concern is cosmetic rather than leakage, theres no point in filling with normal filler cos as Vyv has said, it will crack. I eventually had the yard use some "flexible" filler, which I think was Silkaflex. This is fine save that Antifoul now cracks along that line.
Life is too short
<P ID="edit"><FONT SIZE=-1>Edited by dcaukill on 03/10/2002 13:35 (server time).</FONT></P>
PuffTheMagicDragon
Well-Known Member
For what it's worth - and I'm pretty sure that there may be some nameless ones on this forum who will be in total disagreement - consider the following.
When I was doing some work for an italian builder in the mid-80's on 42-foot boats, the system was to sandwich a shaped plank of wood between the keel casting and the canoe body. From memory, this was around 20mm thick. The wood that was used was 'pioppo italiano' which, I believe, translates into 'italian poplar'. This was buttered up with a microballoon / resin putty on both surfaces and the hull was then lowered onto the fin. The keel bolts (11 x M25 and staggered) were only tightened the next day ensuring that the putty did not ooze out. This process effectively neutralised any imperfections on the top surface of the fin from damaging the hull proper.
The join lines were then made good and the entire surface of the fin was later filled and faired using a similar mixture.
The philosophy behind this approach was that any movement of the fin in relation to the hull would be taken up by the wooden liner. This was of a very even, close, grain and would take up enough water to maintain a tight seal.
If you are planning to drop your keels you might wish to consider this solution. If you are only concerned about appearances, then don't bother.
Incidentally, some of these boats were built as racing machines, mainly for the american market, and the system worked. The designer was Andrea Vallicelli who had at that time designed 'Azzurra', the italian challenger for the America's Cup under the old rules.
Fair Winds!
Wally
When I was doing some work for an italian builder in the mid-80's on 42-foot boats, the system was to sandwich a shaped plank of wood between the keel casting and the canoe body. From memory, this was around 20mm thick. The wood that was used was 'pioppo italiano' which, I believe, translates into 'italian poplar'. This was buttered up with a microballoon / resin putty on both surfaces and the hull was then lowered onto the fin. The keel bolts (11 x M25 and staggered) were only tightened the next day ensuring that the putty did not ooze out. This process effectively neutralised any imperfections on the top surface of the fin from damaging the hull proper.
The join lines were then made good and the entire surface of the fin was later filled and faired using a similar mixture.
The philosophy behind this approach was that any movement of the fin in relation to the hull would be taken up by the wooden liner. This was of a very even, close, grain and would take up enough water to maintain a tight seal.
If you are planning to drop your keels you might wish to consider this solution. If you are only concerned about appearances, then don't bother.
Incidentally, some of these boats were built as racing machines, mainly for the american market, and the system worked. The designer was Andrea Vallicelli who had at that time designed 'Azzurra', the italian challenger for the America's Cup under the old rules.
Fair Winds!
Wally
vyv_cox
Well-Known Member
That's a neat solution. Using a material that swells in water seems an excellent way to allow for the imperfections. One of the few good uses for wood on a boat that I have heard of!
Incidentally, my son has told me of several cases where a Sikaflex joint held the keel on after the bolts were all removed, despite the boat hanging in the slings and the keel being attacked with heavy hammers.
Incidentally, my son has told me of several cases where a Sikaflex joint held the keel on after the bolts were all removed, despite the boat hanging in the slings and the keel being attacked with heavy hammers.
spark
Well-Known Member
One of the few good uses for wood....
Harrumph!... I can't think of any good uses for fibreglass (except perhaps lining the back of the fish van).
Harrumph!... I can't think of any good uses for fibreglass (except perhaps lining the back of the fish van).
JamesS
Well-Known Member
The reasons are purely cosmetic - no sign of leaking.
It's just that there is a ugly edge where the roughness of the iron keel meets the grp hull.
Cheers
It's just that there is a ugly edge where the roughness of the iron keel meets the grp hull.
Cheers
