Wood and glue.

I used Iroko for the gunnels of my dinghy, real mahogany is difficult to come by since the import ban and sapele and maranti are not as stable around seawater. I got a plank from AC timbers at Ely 38mm x 150mm x 3400mm for £34 inc. I did get a local woodman to rip it for me, this was for several reasons, Iroko as has been said is an oily wood and grabs the blade (especially if like me you don't use a riving knife on the table saw), I'm a long way down the yard and the voltage drop would kill my saw cutting iroko.
You won't need to go to the expense of structural fillers, the bond is more likely to fail on the foam core than the epoxy. If you don't have enough clamps, you can screw into the first rail and then remove the screws once cured, a dip in wax is enough to allow the screws to come out again.
Oak turns black (actually a very dark brown) with epoxy because of the iron content. I think you will have a major problem putting on the capping rail, as it is going to be a wide piece of timber. maybe better to fit in two pieces and band saw the curve, just a thought. There is a guy who's name eludes me but advertises on the Canadian Canoe Forum who sells epoxy at a reasonable rate.
 
When laminating some 7mm european oak into beams a few years ago as a mast step supports, I used a 5 minute polyurethane glue.
My son has a large workshop and we had space to set these out onto mdf formers.
We attached the 1st lamin onto the former with nylon staples fired from a gun.
The rest of the lamins were attached with 5 minute polyurethane also held down with plastic staples.
Using this process we were able to make the former, lay up the lamins, put through the thicknesser x3 in the same evening. Plastic staples are planeable!
You can use a slower drying polyurethane glue to assist with slower clamping up etc. but the secret is to have no gaps and tightly clamped workpiece. Polyurethane has tremendous strength like this and is totally waterproof, but as said, gaps of foam have no strength.
When I've done big 'glue-ups' I try to make myself do a dry clamp-up to sort out some of the unforseen problems before doing the glued clamp up.
 
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Allan, sorry to hijack the thread a little.
To those guys experienced using epoxy.... I'm thinking of putting a quadrant beading at the bottom of the teak coach house join to the GRP deck.
Would this be best made up of very small lamins to give strength?
I do have a few very gentle curves and then some radiussed corners to get round.
How would you advise it being held tight in position while all goes off? Should I pin it in place? What pins etc?
ta
S.
 
TQA said:
No fixings required. The only benefit of fixings are location while the resin sets.

The tensile strength of West epoxy is around 7000 lbs psi.

The bond strength [even with a silica filler] is greater than the strength of the wood.
Click to expand...

Not the wood I would worry about, but the GRP composite that the wood is attached to.
 
Hello Allan and all,
why don't you want to use fasteners in place of glue? It would be a lot quicker, less messy, but more importantly it would allow you to repair/renew your rubbing strip/gunwale more easily when needed... Precise spiling, care in choosing your wood , a through bolt (3mm) every 250mm capped with a plug. If you are worried about water ingress inbetween skins, a very thin bed of mastic/leadputty or even Sika should do the trick... No need for atmosphere control/heating, gloves, masks etc... Cheers. Al
 
Scotty_Tradewind said:
Allan, sorry to hijack the thread a little.
To those guys experienced using epoxy.... I'm thinking of putting a quadrant beading at the bottom of the teak coach house join to the GRP deck.
Would this be best made up of very small lamins to give strength?
I do have a few very gentle curves and then some radiussed corners to get round.
How would you advise it being held tight in position while all goes off? Should I pin it in place? What pins etc?
ta
S.
Click to expand...

What dims / radius beading?

I think I'd hold it together with screws while the epoxy sets. Epoxy can't stand a bit of slackening off as it sets. I'd use temporary screws in pilot holes with penny washers, then remove the screws, drill through and epoxy dowels in place, capped / plugged with the trim timber of your choice.

No metal left behind, new plane introduced to glue joint.

Max
 
maxcampbell said:
What dims / radius beading?

I think I'd hold it together with screws while the epoxy sets. Epoxy can't stand a bit of slackening off as it sets. I'd use temporary screws in pilot holes with penny washers, then remove the screws, drill through and epoxy dowels in place, capped / plugged with the trim timber of your choice.

No metal left behind, new plane introduced to glue joint.

Max
Click to expand...

Hi Max,
I guess the radii to be around 100mm at the corners of the coach-house/doghouse and back of cockpit. I thought the bead/quadrant could be around 30mm high by 25mm wide.
The back edges need to be angled to suit the slant of the coach-house sides and possibly undercut a little to ensure enough epoxy is in there?
The one problem I have is this teak of the coach-house sides. With its own oils I guess I'll have to 'dry out' the teak with plenty of acetone to get a good key with the epoxy?
What I'd ideally like to do is to cover the teak sides in GRP as the roof is GRP and so are the decks. I love wood, but it can be a maintenance concern.
If I knew I could treat it with some magic formula to make it totally and permanently watertight and look good I would.
 
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NOHOH said:
........of using this stuff.... http://www.ct1ltd.com/ct1.html It does bond to fibreglass and is tolerant of uv and a saltwater environment....
Click to expand...

Is this a similar product to Evo-stik Sticks like Sh*t? I've just started using the latter and think it's fantastic. As it can bond underwater I wonder if it would be worth carrying some together with some thin panels of GRP, say one layer of CSM, for emergency repairs.
 
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great info so far .

read that you have to be careful that the epoxy doesnt get squeezed out of the joint ,making it dry, and so an epoxy joint should be closed up , but not squeezed up .
just joined for advice and hope you dont mind me posting within here . going to be joining lengths of 6mm ply on a curve , to form an 18mm thickness ( plies vertical ) please suggest a glue specific for this use . need the join to be strong and so wondering if not to use epoxy as the joint will be tight and clamped so the glue could get sqeezed out . ta
 
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