Performance Factors

How long is a piece of string?

Varies enormously with wind and waves and point of sail.  Example:

Cherub v 49er z 14 v 12' Skiff Weymouth, light wind.  49er/14 disappear (waterline length) Cherub same speed as 12 upwind (less drag from rig as non-wiring conditions, better pointing, hull shape and ability to keep crew forward better for light conditions), 12 dissapears from Cherub downwind (sail area and angles) but still not as fast as 14/49er round the course.

Cherub v 49er Weston Skiff event, medium breeze, solent shop.  9er much faster upwind and through tacks (Cherub stops dead!), however Cherub nearly as fast sometimes faster downwind in the gusts.  LWL irrelevant as very little of Cherub in the water.

12' skiff v 14 yesterday, Draycote, windy. 14 much faster uphill (more rag and more LWL than 12) until wind pipes up a notch, 14 overpowered,12 sails out from underneath (*puts tin hat on and waits for the forum fun to start!*).  Downwind 12 is faster due to angles and kite area and weight.

Just too many variables I think!

If I put it in my simple terms, straight line performance is about drag versus power.  However, as the ad says, power is nothing without control.  If you want to perform, then surely the foiling moths show that what is important is low drag in a controllable package (without the auto-wand on the Moth the controllable bit isn't there and you don't go very far).

So, if you colour the picture on all the things listed above with the ability to maintain control, then you get a pretty good picture of each.

Length - reduces drag at displacement speeds and improves controllability at higher speeds.

Weight - need to differentiate here between moveable ballast and fixed ballast - lighter fixed weight is generally faster but too light and the lack of momentum starts to hurt.  More moveable ballast is generally better and the more it can be moved the better (in general) - but then you get back to the limits of control.

Righting Moment - more is generally better but there are limits as you still have to control the beast (18' skiffs on Waterloo Bay versus Sydney Harbour is the classic example - smooth wind in Waterloo bay made control easier so the boats got wider and faster).

Sail Area - more is better up to the limit of control / power etc etc

etc etc.

Hmmm, I actually thought we (12) was sailing lower than the 14 downwind but I'll stand corrected.  You were certainly outpointing us uphill!

Thinking about it we were probably sailing artificially high to try and get the reach down into Toft Bay and also give us a few options if a big gust came in.  We were on the knots with the main well out for a lot of it, there was the anchored committee boat that seemed to be in the way most of the time too (as a 20 foot boat would be on 700 acres...) 

I think if we had been VMGing it then we would have poked it a bit lower and also sailed a bit flatter.  Don't suppose you had a GPS on board did you? Be interesting to compare tracks...