glueing a wooden mast back together

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Castletine

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I have a wooden mast on my GP14 dinghy.

It was originally constructed in two parts in the vertical and glued together. This glue has now weakened and the mast has come apart, after cleaning the surfaces, what should I glue it back together with?

Thanks in advance

Jonathan
 
Aerodux resorcinol glue if you're a die hard originalist and like to do things the complicated way. Otherwise use epoxy. Preferably West System but follow their instructions!
 
I used epoxy on a 26 foot mast a few years back. mast still 100% and in regular use. Using Epoxy, make quite sure you clean back to bare timber and leave none of the original glue.

Use as many clamps as you can beg borrow or buy to hold it all together for gluing to avoid any possible gaps.

Splitting the old mast may be fun where the glue is still holding. I cut the glue join with the thinnest jig saw blade I could get, rather than risk splitting the timber by forcing it apart. I used fibres in the epoxy to make a good gap bridging glue.
 
I really wish that I had seen this a while ago!
Before I'd even taken a sailing lesson I bought a second hand dinghy from ebay; erected the mast in my driveway to inspect my purchase - well pleased. Then found out, don't move the boat on it's trailer after releasing the forestay....
TIMBER!!!
Didn't have any problems splitting the mast, found a nice sharp impact did that perfectly well! /forums/images/graemlins/laugh.gif
All ok now, but still waiting for a test sail.
 
hi, i laminated my 50ft mast using resorcinal resin , 8 years ago, still perfect . also the above is actually pleasant to use, sort of hospital disenfectanty smell , and washes off withwater.and perhaps more important , it has stood the test of time. you just have to take a bit more care with the mating surfaces. which ,with all the cheap power tools available now, isn't such an issue as it was many moons ago.
 
Thanks Guys,

I've also heard that adding wood flour to the epoxy mix adds flexibility and strength - any one agree/disagree?

I'm a little reticent to expoy sheath the whole mast as it is already a hefty weight and I don't want to add more weight topsides on my small dinghy.

The mast came apart in my hands and I had a lot of fun cracking it open - clean split, there was nothing left of the glue - the Australian sun saw to that.

Now to start sanding it all down.....
 
When we rebuilt the mast of our SCOD a few years ago, the surveyor adviced me NOT to use Epoxy as it is too brittle. He suggested a modern recorcinal resin such as Cascophen. Its used on aircraft and is completely weatherproof. Its also a lot more resistant to UV. Its no more expensive than epoxy and I was very impressed with the stuff.

I normally use epoxy (usually West system) for just about everything so I was a little cynical at first, but the surveyor knew what he was talking about... I split the mast down its glue join for its entire length and borrowed 40 or 50 clamps from a friendly woodwork shop. Set it up straight on tressles and ended up with a straight and strong mast that won me some silverware.
 
Not sure about wood flour adding flexibility, but it's handy for colouring epoxy resin if you need a match, Just rout some bits of the wood you're matching and collect the dust.
Wood flour is also great for adding body to resin so you can use it for fillets or upside down or as a gap filler.
The silica and other additives don't reduce the slump so the resin still runs away before it sets.
 
Whatever you do, don't epoxy-sheathe the mast. Hubbie did it on his GP (2167 - 50 years old and still going) about 10 years ago, and the UV broke down the epoxy within 18 months. Given Aussie sunlight, your's may not last a summer. Go for either a normal UV filtered yacht varnish, we've had good results with Le Tonkinoise. You could go for Coelan - but, as with epoxy, you must make sure every scrap of varnish has been removed.
 
Yep, you need to paint or varnish and expoxied surface to protect it from UV. The advantage is that the epoxy will stabilise the surface so the wood doesn't move so your paint or varnish lasts much longer.

So each protects the other.

You can get considerable life out of this type of arrangement... but it has the same drawback as a pure varnish job. Let it go a little bit and you will be having to scrape back to bare timber to start again.

I would say that epoxy under standard varnish coats would double the life of the job - from a couple of 35ft boat masts that I helped do a few years back. But the owners were conscientious about keeping the varnish up.

Another good thing about the epoxy is that it can all be applied in one day - by doing three coats wet-on-wet. Apply one, wait for it to go tacky, apply the second, wait for it to go tacky, then the third.

You can't apply with brush as it is too uneven and you will get runs - you need to use the right kind of roller - thin foam from an epoxy resin supplier.

You can get a good finish after rolling by holding the roller so it can't turn and slowly and gently sliding it across the surface to slick it off.

Michael Storer
 
Not too keen on epoxy sheathing the mast, only in using epoxy to glue the two pieces back together again.

I like the sound of Cascophen, does anyone else have experience with the product?

I also have grand plans in returning the old girl to her former glory, there's not much wrong with her, so the pressure is on to get her back in action as it is summer here, followed by new decks planned for winter
 
[ QUOTE ]
When we rebuilt the mast of our SCOD a few years ago, the surveyor adviced me NOT to use Epoxy as it is too brittle. He suggested a modern recorcinal resin such as Cascophen.

[/ QUOTE ]
I can't agree that epoxy is brittle - I've done tensile testing on epoxy test pieces and the strain they withstand before failure is surprisingly high. I've only ever used the old fashioned Cascamite glues (the powder type that is mixed with water), which I've personally found to be very brittle. There seem to be a number of different glues under the 'Cascamite' and 'Cascophen' labels nowadays, and not having used them I can't comment.
Epoxy would be a good choice only if you can be sure of getting the mix proportions and the curing conditions exactly right. 2-part resorcinol glues like Aerolite are more forgiving in both these respects.
 
Hi there,

Thanks for that, I've been asking around and been told the same, so I shall be sheathing the mast!
I'm hoping to have the whole mast sanded down over the weekend.

Cheers,

Jonathan
 
Interested in your 50ft mast; My boat originaly had a 45ft square section timber mast, long since replaced by ally, I would like to go back to timber ( just for the anorak value ). What was the process,timber,glue etc. that you used?
 
Wooden composite masts, (four pieces) are often douglas fir, or spruce. Glued together with either cascamite or epoxy, scarphed together to make long lengths of planks/square sections. I wouldnt be thinking of making my own 50 foot mast and I know what I´m doing, I´d have it made. IMHO

Welcome to the forum by the way.
 
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