Blackmagick Sails
Mast Rake
Mast rake is another aspect of trimming for best sailing balance. Not only that
but balance aside most boats will sail faster in a breeze if you can induce a little
mast rake aft. Sometimes this is hard to do, as weather helm increases with the
stronger breezes raking your mast further aft usually increases the helm still
further! If you can move your mast forward at deck level to counteract the helm
that's great, do it! But if your mast is stepped through the deck it is not so easy
to figure. Perhaps you can move your jib a little futher forward to counter the
mast going aft? Sail with more twist in your mainsail? All boat designs will react
in a slightly different way, I know the Austalian TS2 sails well with quite an
amount of aft rake, my Eureka likes a lot of aft rake in the 'B' rig, all you can
do is experiment, get one of your friends who has a boat of similar speed to go
down to the lake with you and spend a day trying different mast rakes. You
might have to try it in differing wind strengths before you can be sure you have
the best combination. Here we see GBR 08 has quite some aft rake in it's 'B'rig.
Here's a good illustration of sail twist. And just why do we need twist in light
weather some might ask? Even with these small boats we have such a thing as
wind shear, or wind friction of the surface of the water,  quite simply the air is
moving faster a metre or so above the surface of the water so the sails need to
allow for this by twisting off a little at the top. It has been suggest this effect is
cancelled out over 5 knots of wind strength, but twist still needs to be used.