Hull/Deck Joint Repair

For my pains I have been saddled with the task of formulating a repair scheme for the hull/deck joint of a 5.7m (19ft) boat, of French manufacture. It seems to have originally been stuck together with some kind of adhesive, and covered over with a U-shaped plastic/rubber rubbing strake. There were 3mm bolts through , at 1m intervals, but I had always thought these were to secure the rubbing strake, as no adhesive succeeds in doing this. This season, for some reason many of the bolts lost their nuts and fell out, due to heavy use for sail training, resulting in the joint parting near the chainplate, and the joint pulling apart due to rig tension. Could anyone out there advise on the best way to effect a repair?
 

30boat

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For my pains I have been saddled with the task of formulating a repair scheme for the hull/deck joint of a 5.7m (19ft) boat, of French manufacture. It seems to have originally been stuck together with some kind of adhesive, and covered over with a U-shaped plastic/rubber rubbing strake. There were 3mm bolts through , at 1m intervals, but I had always thought these were to secure the rubbing strake, as no adhesive succeeds in doing this. This season, for some reason many of the bolts lost their nuts and fell out, due to heavy use for sail training, resulting in the joint parting near the chainplate, and the joint pulling apart due to rig tension. Could anyone out there advise on the best way to effect a repair?
If the split is localized maybe squirting some fresh sealant into the gap followed by new screws to tighten it could work.
 

lw395

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......., resulting in the joint parting near the chainplate, and the joint pulling apart due to rig tension. Could anyone out there advise on the best way to effect a repair?

Sounds like it needs a serious repair which will be stronger than the original?
May be a knee or something to take the chainplate loads around the hull/deck join and properly into the hull structure.
Were the 3mm bolts just there to hold things in place while the glue set?

It may be the bond was enough, but a few knocks in the same place has seen it off?
I've had a dinghy like that, cleaned out the join and injected warm WEST, good result.
 
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Sorry, I perhaps could have been more helpful, but generally sikaflex does everything!

I have a 22' French boat with a similar set-up, at the joint the rubbing strake is bolted to an identical piece of wood on the other side. On mine the bolts are much closer together, perhaps every 250mm, I haven't had any of it apart to see what is in between but I imagine the purpose of anything in there would be just as a sealant.

If you slacken off the rig perhaps the joint will close up again then you could put in any old sealant and increase the number of bolts around the area of the chain plates.
 
Sounds like it needs a serious repair which will be stronger than the original?
May be a knee or something to take the chainplate loads around the hull/deck join and properly into the hull structure.
Were the 3mm bolts just there to hold things in place while the glue set?

It may be the bond was enough, but a few knocks in the same place has seen it off?
I've had a dinghy like that, cleaned out the join and injected warm WEST, good result.
Yes the rig will certainly have to come down, it's a job that can be done manually by 3-4 bodies. My original thought for a repair medium was, as you suggest, resin.
Your comment about a few knocks causing weakness is relevant, as we have six of these boats and during end-of-course racing they can be magnetically attracted to each other. T-boning is not uncommon. We used to have professional staff running the base and doing the maintenance, but in recent times this burden has fallen on the shoulders of members to do on a voluntary basis, with a shrinking pool of expertise. What you say about reinforcement to take the chainplate loads has set me thinking; a knee in that area might also spread the damage in the event of a collision, but my own boat , a Dufour 30 Classic, which used to belong to the club, had had a number of factory modifications, among which was moving the chainplate location from deck to topsides, Perhaps this might be a solution to prevent this kind of thing happening again, to this boat and to our fleet generally. But there is a committee involved..........:)
 

30boat

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Yes the rig will certainly have to come down, it's a job that can be done manually by 3-4 bodies. My original thought for a repair medium was, as you suggest, resin.
Your comment about a few knocks causing weakness is relevant, as we have six of these boats and during end-of-course racing they can be magnetically attracted to each other. T-boning is not uncommon. We used to have professional staff running the base and doing the maintenance, but in recent times this burden has fallen on the shoulders of members to do on a voluntary basis, with a shrinking pool of expertise. What you say about reinforcement to take the chainplate loads has set me thinking; a knee in that area might also spread the damage in the event of a collision, but my own boat , a Dufour 30 Classic, which used to belong to the club, had had a number of factory modifications, among which was moving the chainplate location from deck to topsides, Perhaps this might be a solution to prevent this kind of thing happening again, to this boat and to our fleet generally. But there is a committee involved..........:)

A few pictures would help a lot.I'm sure the repair is easy but looking at the damage would help a lot in the ideas department.
 

William_H

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On a boat that size I imagine the chain plate is a U bolt or saddle through the deck relying on the deck to transfer load across to the hull and down to the mast base or suport. This means the shroud load is carried through the deck hull joint.
I would inject epoxy (being more viscous) into the gap before removing shroud load and adding more bolts to the join.
To carry the load chain plate to hull however a better arrangement might be to add a saddle to the bottom of the U bolt, connect wire and a turnscrew to carry down to a plate on the hull. Thus transfering shroud tension to the hull. The plate can be a piece of SS sheet with large holes in it and a turn up to take a hole for shackle to connect to brace wire. The plate is epoxied to the inside of the hull. Then fibre glass is laid over the top with na overlap onto the hull. (and connection f/g to hull through the large holes). When hard tighten the turnscrew to pull the deck down a little.
Or as said you can fit a knee epoxied in to take the load to the hull. Finally quite loading up the rig with so much static tension (no matter what Mr Selden says he doesn't care about the hull strength.) olewill
 

Seajet

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A couple of years ago I replaced the U section plastic rubbing strake on my 22' boat as it had gone brittle, largely down to U/V.

The T section alloy tracks it goes onto was beginning to corrode so I took those off, cleaned them down and treated with Dulux Metalshield primer & topcoat ( I've tried all sorts of steel & alloy treatments inc for my steel keel and this stuff is way better than the rest ).

I reattched the tracks with more bolts, in fact a total of 72 marine stainless 4mm to cover both sides.

In your case I think you need to glass the hull / deck join internally as well with a substantial mat.

I had a lot of trouble finding the right D section rubber strake, normal suppliers like Wilkes couldn't help; then I found just the thing new by the reel on E-Bay.
 

Fantasie 19

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Yes the rig will certainly have to come down, it's a job that can be done manually by 3-4 bodies. My original thought for a repair medium was, as you suggest, resin.
Your comment about a few knocks causing weakness is relevant, as we have six of these boats and during end-of-course racing they can be magnetically attracted to each other. T-boning is not uncommon. We used to have professional staff running the base and doing the maintenance, but in recent times this burden has fallen on the shoulders of members to do on a voluntary basis, with a shrinking pool of expertise. What you say about reinforcement to take the chainplate loads has set me thinking; a knee in that area might also spread the damage in the event of a collision, but my own boat , a Dufour 30 Classic, which used to belong to the club, had had a number of factory modifications, among which was moving the chainplate location from deck to topsides, Perhaps this might be a solution to prevent this kind of thing happening again, to this boat and to our fleet generally. But there is a committee involved..........:)

On my old boat, I let off rig tension, put a couple of lorry style ratchet straps round the hull and tightened them down, and then just sanded/ground the inside of the join and put 3 or 4 layers of epoxy mat over it....
 
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