Debunking Dodgy Sailing Theories

Originally posted by JohnW Originally posted by Rupert Just found this thread... How is that drawing anything like a mark rounding? If I'm rounding in wide out tight, my curve still wouldn't take me below the mark - in fact, I'm not sure it would be a smooth curve at all, especially if there was a gybe involved. Also, racing is about clear wind. If I go round the mark with the apex thing you are talking about, and supposedly gain a boat length, if that puts me in another boat's dirty wind, I'll loose far more up the next beat. If I get inside the boat I was following, I have the tactical upper hand. If you come out tight then you cant be doing an apex turn (unless the mark has the same radius as your turn) and therefore by definition you are rounding below the mark.   My post says that the apex turn is the fastest, not always the best tactically. But when there are no other boats about it is faster.   Originally posted by Rupert Another myth - the outhaul should be pulled tight in light winds upwind. OK, I'l bite.   Surely that depends on the boat and the cut of the sail.

I agree that lots of sailors bang the outhaul on tight in most conditions ( and really tight when its windy), and its not fast. Obviously in a drifter you can have it out tight, but as soon as there is a bit of "weight" in the wind and all the tell tales are flowing, you can afford to put some depth in the base of the main. As long as you don't overdo this and make it too deep ( very slow!) it will give you a really good profile to the lower leach of the main ( return at the bottom batten) which can be used to give you great pointing ability. This will work up to max power conditions when you will then have to flatten things off again.

Originally posted by Rupert Why have it out tight in a drifter? I've been winning in no wind for as long as I can remember (wish I could do so in breeze) with a fairly full sail. All very well having attached flow, but with no drive and a board flat sail that is impossible to read the windshifts with, you'll be going in the wrong direction, slowly. Let the sail breathe. I'm always amazed at seeing creases in the foot of a sail in those conditions.

Menace,
You aren't wrong regarding the NACA studies, but remember NACA studies were performed in wind tunnels with solid wooden models, not soft sails. On a solid aerofoil the boundary layer flow may seperate but will ultimately continue flowing around the section enabling re-attachment. Outside of the boundary layer the flow may stay laminar and perform reasonably well. With a soft sail seperation leads also to loss of shape, which in turn makes re-attachment difficult. A tight foot will minimise the likelyhood of seperations but will limit the ultimate rig forces. Sailing free-er gets you back some of the lost drive.

As you alude to, if you can keep flow attached over a deep section then it will be quicker, but in zephyr conditions this takes very careful and sensitive trimming and most people won't be able to keep it going. If you can then well done.

In a light wind which is not steady, the apparent wind can be a long way forwards in the lulls. A fairly flat main helps avoid or limit backwinding when this happens.

Sails and rigs vary. If you are sailing a boat where you ease the sheet a lot in light stuff to get more twist, the main can get very full on some boats unless the outhaul is pulled on reasonably, because the lack of mast bend will make the sail fuller than on a beat in F3.
It may help to try to talk about % camber rather than how far the clew is pulled out.

A two-boat drag race helps work out what works in a particular boat.

Also, what some people call 'light' others are thinking, 'let's postpone until the wind arrives'. I'm thinking about those days when we struggle to make progress at all against the tide.