Wood and glue.

Allan

Allan

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I need to laminate some wood around the gunwales of a dingy I shall be working on soon. I would like to just glue it without any screws or other fixings. What is the best combination of hardwood and glue for this purpose? At present I am thinking of mahogany and epoxy but would be grateful for any other suggestions.
Many thanks in advance.
Allan
 
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SHUG said:
Balcotan used to be the best option but has been superceded by another epoxy glue.Someone will be along in a minute with the name of the replacement.
Oak is a good wood for around the gunwale as you can steam it to bend and it's pretty tough.
PS I have checked around and Balcotan is still available.
The replacement is here:
http://marinestore.co.uk/Merchant2/...&Product_code=HA1439&Category_code=wood-glues
Click to expand...

I think you will find that Balcotan is not an epoxy but a (single part) polyurethane which cures by reaction with moisture ( and foams as it does so)

The foaming nature means it only needs to be applied to one surface, and is good for penetrating and filling small spaces and crevices without filling the joints first with excess glue.
However because the cured material is foam it is not a good structural filler.

Like wise the one in your link.

Gorilla glue is a similar polyurethane which is readily available.

It's a while since I did any serious woodwork. I think, though, I would try one of these polyurethanes if I were to do any.
 
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Many thanks. I agree that the foam is not what I'm after, I need more strength than that. I will look into the relative strengths of Polyurethane and epoxy.
Allan
 
I am no timber expert, but I've heard that oak can go black in this kind of application if any moisture gets into it. An aesthetic rather than structural problem, I believe, but still not good.

Anyone with more knowledge able to confirm?

Pete
 
Guess your talking about the carbon dinghy......speak to S.Wales joinery 01495246962. Brilliant work and based near you.
 
Are you talking about laminating wood to wood to make up a rubbing strake or gluing a wooden rubbing strake to the top edge of a fiberglass dinghy - ie a wood to fiberglass joint? In the first case I would probably use an epoxy or Balcotan. In the second case I would be being doubtful about a glue joint onto gel coat. If there is no gel coat, then epoxy would be what I would use. You could consider iroko. It's been very successful on my pulling dinghy but then I have an iroko strip on either side of the fiberglass screwed together with countersunk and plugged screws. Can you tell us more?
 
Sorted a wooden FINN years ago. Stripped the decks and fitted new gunnals. You need lots and lots of small clamps. We used a waterproof pva wood glue and built the gunnal up in thin strips with overlaps where required. The same principal is used on some Enterprises where they use a sandwich construction of teak and a lighter wood to give you a banding. Looks very effective when sanded and varnished. It also gets round the problem with the hardness of teak and trying to bend it. Thin teak will bend :)
 
Tillergirl, the pram dingy is fibreglass matting over a foam core. The sides are around 15mm the front and transom are about 20mm. There is no gelcoat. I plan to make the rubbing strake out of three bits of wood, one on the top edge then two pieces, one each side. I plan to glue this onto the fibreglass with epoxy but I'm looking for information about which wood/glue combination would be best.
I'm reluctant to use teak as I understand the oily nature makes gluing more difficult.
Allan
 
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Spruce or pine 1/8th to a 1/4 thick and epoxy. Get some west system laminating epoxy used neat on the wood to wood joints and maybe with some silica where you are joining to the fibre glass if there are gaps needing filling, wood fibres will work as well.

A wood like sapele could be used for a contrasting colour in bands if you are varnishing.

BTW fibre glass using polyester resin is fibre glass gelcoat or not.
 
You will find you will need fastenings even if you use epoxy. An inner and outer Gunwhale of about 15 mm each should bend on a pram OK. Do the inside first with screws through the shell into the wood - but you will still need lots of clamps and at least one spreader to keep the shape of the hull. Then do the outside with screws in a counterbore right through to the inner. Plug the holes with 9mm plugs. You can use mahogany for this. Teak would also work, as would iroko if it has straight grain.

Your real problem will be the capping piece because that will be 45*15mm which will probably not take the edge set. One alternative is to make the inner and outer 45mm and leave a 20mm gap which you can then fill with a spline.

As for adhesive, probably best to use epoxy as, although polyuerthane will be fine for the wood, not sure it will work with wood/grp.
 
Many thanks Tranona, that ia similar to my thinking. I had always planned to use something like 45mm side pieces with a 15mm strip between them on the sides.A thought I have just had is that I may try gluing a 15mm X 15mm strip on first possibly using something like silicon. If this works it should give some movement whilst I epoxy and clamp the side pieces on.
Are there any recommendations for what epoxy to use and a good place to buy it. I live in Bristol, sail from Cardiff and drive around the south and the Midlands for work.
Allan
 
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Similar thoughts, screw the first outer layer through the composite skin into an inner layer. Use ss screws. Then glue a second outer layer with clamps.
Epoxy would be the glue of choice, not sure about PU onto polyester.

I did the gunnels on my double ender in maranti. As it was clinker ply, no screws, all glued with lots of clamps, one inner, two outer layers. And with epoxy, the whole boat has no screws, just glue.
Nothing against Balcotan, but a couple of joints with Bostik PU failed with no reason, so a bit suspect.
If you have mahogany, good luck. But maranti is a good substitute and much cheaper, if a bit softer. Iroko is difficult to find in straight grain and needs degreasing before glueing (acetone wipe) I used it for the keel structure. Oak is reportedly difficult with epoxy due to it's acid content, but no personal experience (glues OK for me).
Teak I have used for a thin, glued on deck. Despite it's oily reputation, it stayed down with epoxy. So, if you want to leave it untreated, a nice look.
 
I would just use epoxy glue. The PU glues will stick if one of the surfaces is porous. I have stuck timber to galvanised steel ok.

I have found though that the PU glues are not strong enough in some cases when gluing timber together where there is some stress. Fine for structural work where the job is to be sheaved with epoxy and cloth.
 
You can get epoxy from just about any chandlers. The main brand names are West, SP and Blue Gee. I have used all of them - they have different mix ratios but all perform equally well in my experience. You will also need a filler such as wood fibres to bulk out the epoxy so that it does not run everywhere. Wessex Resins (West) have lots of good information on their website on how to use their products. Make sure you use protective clothing, particularly gloves - I tend to use Marigolds - pink ones are particularly fetching - as they can be re-used.
 
Tranona said:
......... I tend to use Marigolds - pink ones are particularly fetching - as they can be re-used.
Click to expand...
317H3Gz2NRL._SL500_AA300_.jpg
 
a few tips

If you're going ahead with epoxy and laminates, then here are a few tips

Add one strip at a time and use lots of clamps (every 6 to 9 inches not too many) and allow to fully cure before unclamping (waste epoxy same mix should be brittle hard).

Dry clamp each piece to practice, but remember the epoxy makes things slippery.

Paint bare surfaces to be glued with unthickened epoxy, then thicken mix to consistency of peanut butter. Butter both sides of joint with thickend goo. Ensure you get ooze from every part of the joint.

Do everything you can to tidy up the epoxy while it's unset. Best solvent is acetone. Vinegar OK at a pinch. Wide masking tape far enough away from the piece to allow nicely coved joint.

Use a structural filler such as micro fibre, not thickeners like coloidal silica or finishing fillers like micro balloons.
 
+ 1 for advice from Max above.

Using thickeners will not improve the strength at all, Mocro-fibres is what you need.

I prefer West System Epoxy, mix in wide shallow containers to avoid heat build up.

Buy a box of latex rubber gloves and two gloves on each hand so you can peel one off when things get sticky.

Temperature above 10c and humidity below 73%, this could mean start mixing around 10 AM and no mixing after 2:30 PM.

I would avoid the use of screws in a foam core without first drilling oversize holes and filling with epoxy and fibre mix filler.

Start work on the sunny side and turn the boat around to face the sun before working on the other side.

Use a sealed lid container for all your clean up with Acetone, let it stand overnight with the did sealed, then tip the clean acetone acetone out slowly for re-use, clean the settled rubbish out and your set for another day.

Keep an eye wash bottle handy.

Good luck and fair winds. :)
 
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