ausbinny said..

mathew said..

utcminusfour said..
If there is not a tack strap in use, then any distance between the pulleys will increase twist.

This is an unusual statement. Please explain some of the details.

Generally race / speed oriented sails as below

Tack strap tensions through the foot of the sail (adding more power) loose will reduce power / release tension

but

If both the pulleys are not close together the foot will have less tension (along the leech) opening up the sail (as the tack pulley will be closer to the clew - further from the mast)

Thanks - I understand how more-downhaul gets the corner of the sail gets closer to the pulleys. However the explanation didn't explain the bit about "...can increase twist.

When we use the word "twist" we almost exclusively mean the upper part of the sail, unless we are explicit about the location. I am interested to understand why a tack-strap can influence the upper-part of the sail.

[ I am not sure I agree with the statement that loose-tack-strap will reduce power, but that is a separate-but-related discussion to the twist aspect. In the 90's we used to have the same statement regarding leech tension - more tension is more power is faster - but now we have very-loose leech. ]