The boom snapping thing seems to be a problem particular to the J105. I found this at J105.org :
"There have been a few broken booms. These breaks always occur just aft of the vang
attachment fitting. The triangle formed by the tight vang, boom, and mast, makes the
front half of the boom very rigid. When the boom is tacked or jibed a shock load is
applied and the subsequent force is all concentrated on this point.
This problem seems most prevalent when there are large swings of the boom such as
jibes or beam reach tacks like those we normally do before the start. The big
swing coupled with quick motions makes for big stress on the boom.
The best fix is to ease the vang before the start and at the windward mark. When this is
done the main sail is allowed to act as a shock absorber and the point of maximum stress
is moved aft to the main sheet attachment points. We are not aware of any booms that
have broken back there."
Has anyone heard of a vang breaking the boom on a well-built cruising boat under reasonable conditions? Because I can't find any examples on Google
. And as another poster pointed out, if you can't use the vang on a beam to broad reach, what's the point of having it at all?
No-one with any seamanship would have allowed the boom to bend like it was in that video before the break.