iand said..."Notice keep that mast step nice and short, don't be tempted to go long" why

If the sail is generating a force of X it shouldn't change the force at the join of mast step and spine, the only effect I can see with a longer mast step is a marginal reduction of rake and side lean. I would have thought that a longer mast step is merely like having a stiffener in the base of the mast

Ian
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The glass masts are not designed to take the loads we put on them, we generally get away with it by making a flexible yacht that will spread the load, avoid lots of Aframes and triangulating..
when a gust hits you want the yacht to flex initially ,then start to release the energy stored in that flexing , as power to drive the yacht. If the yacht is too stiff you just lift wheels. Blokarts do it by having a really flexible mast,particularly at the top,so store less energy BUT make good use of what they do store by being really lightweight .
by making the mast step to high you turn the yacht into wheely popper.
. for example the mast step on my CL 5 PROMO is only 250mm . 5.5m sail
as an aside it also makes the yachts easier to stack on trailers and roofracks

anyway ,thats my take on it , but what would I know,

the truth will out when we race

and we will race[}:)]