Skerry Mast Snapped Under Sail

While sailing on the Potomac yesterday in winds at a steady 16 mph with gusts a bit above that, the mast on my Skerry snapped cleanly along the scarf joint (see pictue).  This was actually my second mast, the first having snapped on the same river last year, but that time it broke right above the mast step in similar conditions and was not repairable.

I hate to invest in another mast and want to try and repair this one.  The boat was definitely sailing within its limits.  The mast was bowed under the load, but I was never at risk of capsize.  I was on a broad reach when it happened.  

I am wondering if I just did a bad job glueing it up originally.  I used the epoxy repair kit I got at CLC correctly with measured epoxy and Cab o Sil thickener.  Should I just sand down the mating surfaces and try again, this time with epoxy thickened with wood flour?  Would that make a stronger joint?

 Thanks for any suggestions.remains of skerry mast 

3 replies:

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RE: Skerry Mast Snapped Under Sail

cab-o-sil is what you should use - as wood flour is a filler not a strengthener.

It looks like a nice sort of break, so it should be able to be repaired.

You pic indicates that the sail is tied to the mast, which creates strss-points - unlike a  grooved or tracked mast.

I would question anyone even joining a mast in this manner in the first place. A mast should be flexible, but as soon as you epoxy a scarf joint, you are putting a very large part of your mast into a very rigid state - or at least giving the area around the join a very different bending characteristic than the rest of the mast.


Years ago, when I build a skiff, we built the masts from 2 pieces of clear Oregon. Routed the groove in each piece for the sail track, then aligned and glued the 2 halves togeter.  each bit of timeber was full-length with a single join lengthwise, which gave consistent bending and load characteristics.


We sailed in winds up to 40kn and never had a problem with breaking the boats.

RE: Skerry Mast Snapped Under Sail

It's hard to tell from the pictures, but the fact that it let go along the scarphed surfaces strongly suggests a dry joint. Epoxied properly, the joint itself should be at least as strongly bonded together as the wood fibers in the mast (albiet a little stiffer, as Bob suggests, and therefore possibly brittler and more likely to snap in the general aera of the scarph rather than in the more flexible parts of the mast).

When you make a scarphed joint, you are opening up acres of end-grain, which loves to soak up epoxy, moving it away from the surfaces. It'll even suck most of the epoxy out of a silica or cabosil thickener mix...

Because of that, you need to butter the two surfaces with epoxy and let it soak up as much as it wants, and re-apply as needed, until it stops. Then, apply your cabosil etc and epoxy mix and press togather.

 If that happened in your case (and most peole. myself included have done it once or twice), that soaking has probably already happened (or at least the surfaces are fairly well sealed by the now-hardened epoxy, so just roughen up the surfaces with a rasp or something, put your mix on each part, and press them together.

One other thing: Bob (judging by his moniker and lingo,  and I, are both from Oz (Australia), and when he referred to "Oregon"above, he means the wood USAmericans call "Douglas Fir"...! Bob, please correct me if I'm wrong!

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