"Knot." wrote:

Thanks for the article. I enjoyed the details. A couple of
questions. What does course ca 175 mean? Is this a
corrected heading of 175?

"Ca" should have been "ca." short for "circa" meaning about.
A course was never calculated since it was familiar coastal
waters.

meaning essentially due south. If that is the case, I
understood winds were abeam and behind you when the
mask broke. Also if my math is correct, winds were
21 knots (25 mph) to 37 knots (42 mph) and then you
were hit with a "prolonged gust".

Yes, short time before the mast broke we read a windstrength
of 24.4 m/s (47 knots) - the highest figure we saw, and we
reached a speed of 13 knots through the water.

You were sailing with full main and a full 135 Genoa in
this gust, which incidentally may register as a gale. The
main was against the shrouds and you had trouble
controlling the boat (wheel).
This tells me sails trim was not balanced or you were
constantly on the edge of broaching, which would
indicate to me that the boat was severely overpowered.
Do you think that you had a bit too much sail out for this
air?

Well, yes apparently. The reason being that we wanted to win
the race and that we thought the gear would take the
beating.
Five of the people onboard were fairly experienced - both as
sailors in general and with this boat.
We were all a bit surprised, and though we knew that we
stressed the boat heavily, we thought of the boat as being
fairly strong, and we were not worried until the last gust
when it was to late.
I suppose you could call it a calculated risk, though our
calculations were apparently too "optimistic".
If on a cruise or on a passage we would not take the same
chances if it could be avoided.
Stressing the gear like this is not good seaman-ship, but
our attitude, I guess, is to try to get pretty close to the
limit when racing.

Unless you surf, you will never exceed hull speed anyway,
not with the length/displacement ratio you have. So having
excessive sail out only stresses the rig.

Well, right and wrong. 13 knots is well above "hull speed",
whether "surfing" or not. And we were sailing faster when we
carried full main than when reefed.

What was the status of your backstay? I have seen masks
break because backstay tension was not properly set and
balanced with the forestay. This would make sense in
gusty conditions to me.

The backstay (no runners) were fairly tight but not as tight
as when beating in heavy conditions. The babystay were set
by hand (3-purchase) - not as hard as when beating in heavy
air. The windward checkstay were set by hand (3-purchase)
but the attachment-point were not mowed more than maybe 2
feet back. The leeward checkstay were not set.

We haven't reached any conclusion as to exactly what
happened or why - except off course that we were stressing
the gear to - and apparently over - the edge.
What I think happened is that the middle section of the mast
oscillated forward-aft to much, and that this oscillation
was created by the flapping sails. When the boat bore away
the mast was either already damaged or were "caught in a
extreme position" with no strength, so when the wind filled
the sails, the vertical compression made the mast bend and
break at the upper spreaders, and then when the backstay no
longer could hold the mast back, it swung forward and broke
at the base at decklevel. So what I think was the problem
was more the movement than the stress/pressure in itself.
What I think would have improved our chances would have been
to move the attachment-point of the leeward checkstay well
aft and maybe tightening it a bit more.

No stays or shrouds broke (I am convinced, but not certain).
I cannot exclude some material fault (oxidation) in the area
around the upper spreaders, but I have no reason the assume
that this was the case.

--
Peter S/Y Anicula