Hull - Keel joint fairing

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Ric

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The joint between the GRP hull and cast iron keel on my boat is faired with Sikaflex. This seems a bit bodgy to me and also it tends to start peeling off after a few years. This is not really a problem at the moment as I currently use conventional anti-foul, and the finish is far from smooth anyway after many years of accumuated paint.

However, at next haul out I am considering stripping back to the gel coat and using copper coat, which should result in a much smoother overall finish. Is there a better way to fair the joint that will be permanent, leave a smoother finish, and also be better suited to a coating of copper coat?
 
Ric said:
The joint between the GRP hull and cast iron keel on my boat is faired with Sikaflex. This seems a bit bodgy to me and also it tends to start peeling off after a few years. This is not really a problem at the moment as I currently use conventional anti-foul, and the finish is far from smooth anyway after many years of accumuated paint.

However, at next haul out I am considering stripping back to the gel coat and using copper coat, which should result in a much smoother overall finish. Is there a better way to fair the joint that will be permanent, leave a smoother finish, and also be better suited to a coating of copper coat?
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Hempel epoxy filler
 
In reality, no there isn't. Any fairing that you do with the boat standing on its keel will be stretched or fractured as soon as the boat is in the slings or afloat. If you really want to avoid this you need to fair in the slings, then launch without allowing the keel to touch the ground. Is it really worth it? Not to me, provided the joint is sound and water does not penetrate into the boat.
 
I have a Westerly and the keel/hull join is a perennial problem. It's almost impossible to eliminate all movement between the hull and keel but it can be minimised but not simply. I had a leaking keel bolt and sought advice on this forum. What can be done, if you drop the keel, is to thoroughly clean and de-rust the top of the keel, apply several coats of epoxy, then cover it with cling film and offer it up to the hull with a thin layer of gelcoat/epoxy inbetween. Once the gelcoat/epoxy has gone of the keel is lowered and you should have two surfaces that match exactly. The Sikaflex is then applied and the keel tightened up in the usual way and it should be possible to get a very thin layer of sealant due to the matching surfaces that will then have little movement.

This has certainly reduced the problem on my boat to very small areas of the join that I treat on haul out. I queried this with the copper coat people and they seemed to think they could be touched in without great difficulty as and when required. I would certainly talk to them, you are certainly not the only person who has this problem.
 
Is this "crack" safe?

Interesting thread.
I have a small recurring "seam opening" on port (only) towards the fore-end of my keel (Javelin30). It's approximately 30cms long.
Each time I have hauled-out I have cleaned and filled with Hempel Epoxy, but each year it's back again.
It may only cosmetic, and as I far as I can tell there is no ingress of the salty stuff.
BUT, is it a sign of something more sinister? Or can I sail without fear of disaster?:eek:
 
Robert Wilson said:
Interesting thread.
I have a small recurring "seam opening" on port (only) towards the fore-end of my keel (Javelin30). It's approximately 30cms long.
Each time I have hauled-out I have cleaned and filled with Hempel Epoxy, but each year it's back again.
It may only cosmetic, and as I far as I can tell there is no ingress of the salty stuff.
BUT, is it a sign of something more sinister? Or can I sail without fear of disaster?:eek:
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It is only the keel trying to fall off when you heel over,. nothing more ;)
 
I have owned my boat since 1995. Every time we haul out we note a small gap between hull and keel but no further deterioration has ever occurred. All keel bolts are tight and no water enters the boat. We don't worry about it.
 
vyv_cox said:
I have owned my boat since 1995. Every time we haul out we note a small gap between hull and keel but no further deterioration has ever occurred. All keel bolts are tight and no water enters the boat. We don't worry about it.
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That's the same with mine. Good to know other boats and owners aren't worried.:)
Thanks

sailorman said:
It is only the keel trying to fall off when you heel over,. nothing more ;)
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Thanks!!!!!!! :D
 
Ric said:
The joint between the GRP hull and cast iron keel on my boat is faired with Sikaflex. This seems a bit bodgy to me and also it tends to start peeling off after a few years. This is not really a problem at the moment as I currently use conventional anti-foul, and the finish is far from smooth anyway after many years of accumuated paint.

However, at next haul out I am considering stripping back to the gel coat and using copper coat, which should result in a much smoother overall finish. Is there a better way to fair the joint that will be permanent, leave a smoother finish, and also be better suited to a coating of copper coat?
Click to expand...

When they built my boat, Bowman faired the hull / keel joint by laying down a strip of rubbersied sealant which was maybe an inch wide and overlapped the joint by half an inch on each side. The layer was about 2mm thick. As a seal it worked well.

When my hull was coppercoated, the yard removed this seal, scraped out the joint and filled with epoxy. They then coated. At the time I thought to myself, "this will crack at the joint" but it hasnt. Even after I gave the front edge of the keel a nudge from a rock outside Newton Ferrars. It also help that the keel is lead - no rusting to blow off any coating.

But I guess that depends on how rigid the hull keel joint is. On my boat there is a keel sump and where the lead bulb is bolted on is maybe 4 inch wide so the chance of sideways rocking sufficient to crack the epoxy is small.
 
Thanks - and that brings up the next question - how well does Coppercoat stick to a cast iron keel? I usually have bubbles of rust appearing through the antifoul at most liftouts - does coppercoat prevent this?
 
Ric said:
Thanks - and that brings up the next question - how well does Coppercoat stick to a cast iron keel? I usually have bubbles of rust appearing through the antifoul at most liftouts - does coppercoat prevent this?
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My keel was grit blasted in Greece, in perhaps the best ambient conditions you could hope for, followed by about five coats of epoxy with four or five of Coppercoat on top. Rust comes through.
 
vyv_cox said:
My keel was grit blasted in Greece, in perhaps the best ambient conditions you could hope for, followed by about five coats of epoxy with four or five of Coppercoat on top. Rust comes through.
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I'm not surprised. Iron and epoxy have different levels of heat expansion so minute cracks will develop aided by the copper/iron action.

Spoke to a pro coppercoat painter and he said that coppercoat and ferous metal are not a good mix. He may be wrong but I pass on his remarks.
 
BlueTwo said:
I'm not surprised. Iron and epoxy have different levels of heat expansion so minute cracks will develop aided by the copper/iron action.

Spoke to a pro coppercoat painter and he said that coppercoat and ferous metal are not a good mix. He may be wrong but I pass on his remarks.
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Your professional painter is misinformed. Epoxy is the coating of choice on ferrous structures, e.g. Offshore platforms, ships, Forth Bridge. Coppercoat themselves recommend an epoxy primer. Epoxies don't have to be brittle - have you used Araldite Rapid? Very flexible stuff.
 
Cast Iron is often porous. To epoxy it well, it needs to have been dry for a long time.
The best result we ever got was on a keel from a day boat, which we kept indoors for months while working on the wooden bits. Several coats of west all over and it lasted ten years without significant rust, despite a few groundings.
 
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