Poignard
Well-Known Member
I didn't mean prize it open which, as you say, will only further extend the split.
I meant follow the line of the split with a hand saw.
Best marine glue/adhesive to fix crack in wood
- Thread starter NickC
- Start date
I didn't mean prize it open which, as you say, will only further extend the split.
I meant follow the line of the split with a hand saw.
tillergirl
Well-Known Member
Well, use a router!
fergie_mac66
Well-Known Member
drill
if you have a running crack in any thing . The best way of dealing is a small hole at the end of the crack to stop it running.Then a good hard wood dowel glued in , the hole must be at the v end of the crack.What other posters have said is correct sawing down into the crack but better IMO is a router with a say ....3/16 inch or (4/5/6 mm) straight cutter run along the crack/ split to the bottom of the crack, then glue a good hard wood spline of the appropriate dimensions into the slot.The router is cutting the immediate inter surface of the crack away will remove any softened .. rotting wood any dampness should be dried after the slotting and before the gluing if the crack goes all the way though the same process will stil work stop the crack running further slot, dry, spline and glue but then use a small sash clamp when gluing to squeeze/clamp the glued spline which will minimize the glue line, which with polyurethane, cascamite, cascphen the ideal range of glues , could be a problem.
Epoxy could be used but the conditions must be right to assure a good joint.Damp,heat,atmospheric conditions and any resin ,chemical content in the wood and the particular type of epoxy can all affect the glue line,It will do the job properly but if the conditions are outside of the epoxies tolerance the joint could fail.
if you have a running crack in any thing . The best way of dealing is a small hole at the end of the crack to stop it running.Then a good hard wood dowel glued in , the hole must be at the v end of the crack.What other posters have said is correct sawing down into the crack but better IMO is a router with a say ....3/16 inch or (4/5/6 mm) straight cutter run along the crack/ split to the bottom of the crack, then glue a good hard wood spline of the appropriate dimensions into the slot.The router is cutting the immediate inter surface of the crack away will remove any softened .. rotting wood any dampness should be dried after the slotting and before the gluing if the crack goes all the way though the same process will stil work stop the crack running further slot, dry, spline and glue but then use a small sash clamp when gluing to squeeze/clamp the glued spline which will minimize the glue line, which with polyurethane, cascamite, cascphen the ideal range of glues , could be a problem.
Epoxy could be used but the conditions must be right to assure a good joint.Damp,heat,atmospheric conditions and any resin ,chemical content in the wood and the particular type of epoxy can all affect the glue line,It will do the job properly but if the conditions are outside of the epoxies tolerance the joint could fail.
NickC
Well-Known Member
Thanks for all your suggestions and info.
The crack goes all the way through the rudder, about 5/8" thick.
Drilling a hole at the bottom of the crack and plugging with a hardwood dowel is definately a good idea.
Router also sounds like a good suggestion but personally I can't visualise how I would make a suitable hardwood spline of a consistent thickness, let alone get a dead straight cut with a router for it to sit in.
Now wondering if an alternative might be perhaps a small triangular shape groove both sides, say 3/16" deep along the path of the crack which would allow a bead of epoxy to be dribbled into the slot from either side, then filled up with a mixture of epoxy and micro-fibre. How does that sound?
Still not sure what epoxy to use so will go with 3M 5200 unless advised otherwise.
The crack goes all the way through the rudder, about 5/8" thick.
Drilling a hole at the bottom of the crack and plugging with a hardwood dowel is definately a good idea.
Router also sounds like a good suggestion but personally I can't visualise how I would make a suitable hardwood spline of a consistent thickness, let alone get a dead straight cut with a router for it to sit in.
Now wondering if an alternative might be perhaps a small triangular shape groove both sides, say 3/16" deep along the path of the crack which would allow a bead of epoxy to be dribbled into the slot from either side, then filled up with a mixture of epoxy and micro-fibre. How does that sound?
Still not sure what epoxy to use so will go with 3M 5200 unless advised otherwise.
tillergirl
Well-Known Member
New rudder in my view. I thought originally you were just concerned about water ingress causing rot. But if you have a crack at the Pivot bolt that goes right the way through, caused by the boat sitting on the rudder when not properly lifted, you have an inherent weakness in a pretty crucial part of the boat. It's hard to visualise the damage but I think it is going to be difficult to do any repair that will put back the strength. A photo would really help!
Rigger Mortice
N/A
New rudder or, if you are very lucky, you may be able to split the current one in two and then rebuild it.
Anything else is a botch.
Sorry.
fergie_mac66
Well-Known Member
new rudder best option good marine ply.
Local timber yards for a spline most would find a bit of hardwood 1 or 1 and a quarter by 3/8 ... er 30by10 or 8mm and would run through a thicknesser as for slotting rudder , a peiece or 2 by1 nailed along side thecrack to slide the router along as a fence... a good piece of 5/8 marine play will be far better
and there are places if you google will send you a piece cut to size for shaping
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Poignard
Well-Known Member
I don't see how carefully inserting a new piece of timber can be considered a botch.
If that were so, practically every wooden boat ever built is a botch, since most of them consist entirely of narrow pieces of wood fastened together!
Rigger Mortice
N/A
I don't see how carefully inserting a new piece of timber can be considered a botch.
If that were so, practically every wooden boat ever built is a botch, since most of them consist entirely of narrow pieces of wood fastened together!
A new piece of timber is needed across the full thickness of the rudder and I don't believe that it is possible to force glue into a tight gap to do that reliably.
When a new boat is made the glue would be applied to mating surfaces of the wood which would then be clamped together. (assuming its a glued construction!). There's a world of difference.
A rudder also has to take a fair few forces across the width, so it has to be right.
I'd happily be proven wrong but, FWIW, my view is that trying to splice in a bit of wood as is being discussed would be a botch.
Poignard
Well-Known Member
All good points but wooden boats have always had to have repairs done in situ and modern adhesives make for very strong and reliable joints; also they are easy to use.
Tight clamping is not necessary with epoxy; in fact it is undesirable to completely squeeze it out of a joint.
Tight clamping is neccesary with polyurethane, otherwise it will force the joint apart as it expands during setting. But that would not be difficult to arrange.
I am certainly not in favour of simply trying to inject adhesive into the split. It must be enlarged to expose clean surfaces surfaces for glueing and that enlarged slot must be filled with a timber spline.
However, assuming the rudder is of conventional construction, ie with vertical planks, I would prefer to saw it (or route it) along the split from top to bottom and then sandwich the spline betweeen the two original parts.
(The OP says the rudder is only 5/8" thick so we are not talking about massive timbers here).
If he has a new rudder made that would cost a great deal more than a simple and strong repair.
I would be quite happy to go to sea with a properly repaired rudder.
fergie_mac66
Well-Known Member
Temporary repair
It would be a good idea to put some stainless straps perhaps 25/30mm by 4/6 mm across the width or the rudder in pairs on both sides, bolted through perhaps 6 off 5 mm 3 each side of the crack 2 as close to the pivot to allow the rudder to be raised and 2 further down in addition to any epoxy or opther glue repair.
the 2 straps near the pivot might even be a good idea on a new rudder the bolt heads can be countersunk the other end cut to length and end riveted or peaned over
It would be a good idea to put some stainless straps perhaps 25/30mm by 4/6 mm across the width or the rudder in pairs on both sides, bolted through perhaps 6 off 5 mm 3 each side of the crack 2 as close to the pivot to allow the rudder to be raised and 2 further down in addition to any epoxy or opther glue repair.
the 2 straps near the pivot might even be a good idea on a new rudder the bolt heads can be countersunk the other end cut to length and end riveted or peaned over
davidfox
Well-Known Member
I tend to agree, (my background is construction, joinery, shop fitting, regrettably not boat building apart from a PBO pup!)
You ideally want to join the two halves, so splitting it down the middle and hardwood biscuits inserted, if you have to rout out some rot, then a piece could be let in before you insert the biscuits, then glue up, cramp it all together and then glass over the join? I would feel reasonably happy with that solution.
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