Setting the sails for the conditions
To my mind the foot is set far to flat on this mainsail for the conditions- Alan Hayes Photo
Perhaps one of the things I get asked the most is, how much shape should I put in the foot
of my sail? Probably every top sailor has a different opinion on this one, so all I can do is
suggest the settings I consider the best, and these are obviously going to be orientated
around the design of my own sails. And this is important to note, as the fullness or shape
cut into a sail will dictate in the end how much foot shape you might want to set the sail
with!  Obviously wind strength is the other main factor, so first we shall consider light
winds of less than 5knots.
In 5knots or less you need all the power you can generate, some consider that the sail
needs to be rather flat in these conditions so as not to stall the wind flow around the sail, I
don't! I think sail shape or draft creates drive and dive or power will get your boat moving
faster in light winds...works for me! It might pay to note here I do not cut very much shape
into the top half of my jibs..why? because as the wind gets up, the forestay sags, you can't
stop it all, and it adds a lot of shape to the top section of your jib, if you start with a full top
half you're going to have a bucket up there in over 10knots! So if your jib is a little flat cut
as mine are you do need to induce quite some amount of foot round, to generate sufficent
drive in the light, anything up to 30mm is acceptable as far as I'm concerned. Coming back
to 20mm as soon as there is 5knots or more, how much flatter you want to go after that
could depend on the design of boat you have, I only flatten the foot right out if I'm carrying
the A rig in conditions that suggest I should have the B rig on! A point to note; usually on a
gusty day the wind gusts up only about 50% of the time you are on the wind,  sometimes
even less than this, most of the other 50% or more on the  wind you will be under powered
if you have flattened your sails right. Down hill you will also suffer from lack of power with
flat sails, gusty or not. So if you work it out, over flattening your sails only gives you an
advantage for 25% of the race, which means you could be underpowered for 75% of it, this
is something to think about before you go overboard flatting sails on windy days, better to
let the leech twist off a little more and keep some power in your sails, because gusty days
usually mean choppy sea conditions which require power in the sails to drive you through it
.
What applies to the jib generally applies to the main, I tried flat mains they did not work
for me! The jib is a little different because it gains fullness due to forestay sag but a main
does not, if a main is cut flat it will stay flat, so I have started to build more powerful
mainsails of late because it is easier to flatten a main than make it full, and a little mast
bend helps with a more efficent elliptical profile as the breeze gets up. Even so with a more
powerful main I still seem to have more speed in light conditions with a lot of foot round
induced. As much as 20mm seems to be a go in light conditions, coming back to 10mm in
over 5 or 6 knots, don't be afraid to experiement, these figures are only suggestions your
boat, sail, combination may well respond to different settings than these
The Mainsail
The Jib
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