ATTENTION - MAST SETTINGS !
An A Class rig (mast + sail) has to cover full wind range from 5 knots to 22 knots. In an effort to flatten the rig some sailors are using a lot more Cunningham , together with more Spreader rake and very high Diamond wire tension.
Imagine the mast being so 'pre-tensioned' with diamonds that it is close to its break limit. Then any extra force - even a small capsize - can take it past that limit.
They can also fail from torsional twist.
With full Cunningham and a lot of mainsheet tension the mast gets twisting moment when rotated (so like upwind foiling). Such torsional overloading can induce delamination between the sailtrack sides and back wall.
But you need to stop at some point – it is simply not possible to keep applying more force to the mast – eventually it will reach breaking point. If the sail is still too full with strong Cunningham then you must either try stiffer battens , of less luff curve in sail – the mast can not do it all !
A CLASS MAST SETTINGS
1) Spreader rake must not be greater than 70mm (Diamond wires intersection to rear of mast sailtrack)
2) Diamond wire tension must not be such that more than 20mm prebend is induced into mast
3) Cunningham purchase must not exceed the pre-installed 12:1 system
4) Do not use 'side-fitted' Goosenecks - they can also break masts. Be sure sail Clew ring is correctly positioned so that not excessive force is translated along Boom to Gooseneck.
It is also recommended to release some cunningham tension when sailing downwind - fully pre-loaded mast in downwind capsize is the most common reason for mast failure .
Fiberfoam produce three Mast Sections:-
'A Cat' Untapered Wing mast Section 145mm x 60mm .
Available in different stiffnessess to suit individual sailors.
Also made for F16 , iFly , similar.
Most successful designs for past 10 years.
Tube also used as FD Boom
'A Cat' Tapered Wing mast Section.
Available in different stiffnessess to suit individual sailors.
Most successful Foiler mast past 5 years.
F18 / F20 Untapered Carbon Wing mast Section 74mm x 160mm . Available in different stiffnessess & lengths .
F18 / F20 / Other small boats to mast length 11m