Wood flour won't make the joint any stronger than cabosil, in my experience.  What I'd do is is clean it up, glue it with titebond III or epoxy (your choice) and then wrap it in a layer of carbonfiber and a layer of glass that extended beyond the joint about 8-12" in either direction.  Alternatively, you could just do the whole mast like that, but it will obviously be much more expensive.

FrankP

Did you soak the mating surfaces with unthickened epoxy before slathering on the thickened stuff?  Since a scarph joint exposes endgrain you need to do this. Did you have sufficient clamping pressure? I'm not sure but the picture looks you spread the goop with a notched trowel but didn't clamp enough to spread out the glue.

I'd just plane down to bare wood, soak both surfaces with unthickened epoxy for 15 minutes and re-glue. Get some hose clamps on it. The joint should be stronger than the wood. As mentioned above, glass won't hurt though you may a get an unfair bend if the whole stick isn't glassed.

 If you really want to go town, repair it with clothespin scarf and it will look like a million bucks.

My 7-year old skerry mast snapped just above the  bow seat doubler sailing under moderate conditions. Am looking for a short-term fix for this summer and then maybe  a longer term fix that might include a different sail plan.  The current mast was a non-scarfed Sitka spruce mast. And I fear I may not have kept it well enough sealed.  The boat gets heavy use  2-3 times a week all summer long and sits out on a small lake side dock (in minnesota) all summer long. Any advice welcome.  I'll try and attach a picture.

Gene Severens

Why doesn't the Skerry use shroud lines?  This is not the first time I have read about the masts snapping on Skerrys.  I'm not that worried about the ones that break at the scarf joint--I think they were just not properly glued.  What worries me is the masts that break at the mast partner.

The mast step and mast partner are not that far apart, so there is bound to be a lot of moment arm pressure at the point of the mast partner. 

Any thoughts on why shrouds are not included with the sprit rig?  Would it be a good idea to add them?  If so, what would be the best way to attach them (at both ends)?

My emailed response to Gene, who built his Skerry in spring 2004:

"Gene, so sorry to hear about your mast!  I can tell from your photos
that you have a Sitka spruce mast, which is expensive stuff and
stronger than our own prototype's cypress mast.  There's some
discoloration, some graying of the wood near the break that leads me
to suspect that there was a hairline crack admitting moisture.  Given
how hard you've used the boat, it must have been a cumulative thing
that finally just let go.

You could reuse that mast, but only if you cut a new scarf joint.  (I
know a Skerry builder who did this just a few weeks ago, though to be
sure he broke the mast in a 40-knot thunder storm in NC.)  Your mast
will be 12 inches shorter, however!

We have Skerry masts on the shelf so that's an option.  Or you could
just mill one out yourself.  The Skerry's mast is pretty lightly
loaded as these things go so you don't need something as fancy as
Sitka.  Like I say, our cypress mast from 2001 is still going strong.
Generic northern white spruce (basically 2x4 material) is perfect in
this setting.
>>>>>>>>>>>>>

As for wire shrouds on the sprit-rigged Skerry:  shrouds aren't a good fit for sprit rigs.  The sprit hangs up on the shrouds and will prevent you from squaring out the sail on a run.  And it makes the boat harder to set up and break down.  The sprit-rigged Skerry was designed to be unstayed and quick to set up.  

Breaking a mast is incredibly rare: I know of exactly three including this one, and we shipped the 500th Skerry back in 2011....

Another couple of reasons to avoid shrouds with a sprit rig:

1. They keep the mast from rotating. Not an issue on the Skerry with its square cross section, but sprits are happier when the mast can rotate with the wind.

2. Boats designed for unstayed masts usually won't take the compressive loads of shrouds. That's compression under the mast step as well as the compressive component at the shroud attachment points on the hull which try to pull the hull shut.

Laszlo

Thanks for the valuable info.  Also, I assume the mast is designed to break before damaging the mast step or partner/seat.

If you've got a table saw and taper jig, seems you could just recut the scarfs back 1/2 inch or so and re-glue. Dave 

The mastv appears to be a single stick. I prefer a laminated mast, either birdsmouth or a basic multilayer lamination. Always presoak the wood with striaght epoxy, then add a thin layer of cabosil filled epoxy. Clamping pressure with epoxy should not be extreme, but just enough squeeze to align parts. If thie was an airpane part the FAA inspector would require a "pencil line" thick epoxy glue line.

If you use Titebond II or Titebond III, clamp that suckers until the wood squeaks.