Hello all- Here is a video of a 90ft Catana sailing across the Atlantic. Some gale footage, and some good sailing conditions with commentary.

http://www.youtube.com/watch?v=64zg0lZTDl0&list=UUhcnTuhRZqnOWKFBoBwsJjw&index=1

I have some mainsail trim questions. When trimming, we sheet the jib first, then on the main I aim to have as many telltails streaming aft as possible and as
many telltails on the leach of the sail streaming aft also.

Thing is I'll get all the tell tails streaming as best we can and let the boat speed settle out to say maybe 10K. Then I'll sheet in or out just a little and the boat will often take off, going from 10 to 12 knots, or 12 to 14. The
telltails all still look about the same, but often we get a big boost in speed.

I'm looking for tips on trimming main to the best advantage without this last
trial and error?

Any ideas?

Thanks!

Scott

Hi Scott,

If you are the owner of the 90ft Catana, maybe it would be best if a few of us to come over for a week to help you out with your trimming problems.

I'm not a trim expert but from my experience if the ones on the leach are streaming backwards it means that I'm undersheeting.
Normally I try to make them stream backwards from the bottom of the sail upwards (If the top-most one flows backwards the sail is probably stalled too much).

Could this simply be from the apparent wind shift allowing a tighter trim to flow better?

I've read repeatedly about the need to "stress" the boundary layer on the back side of the sail to get the most out of it. However there is a fine line between "stressed" and "stalled". The latter of course is dead slow.

+ 1 - as the boat gains speed, the apparent wind increases, allowing you to flatten out the sails for less drag (and better speed)