luff length of a sail

[drazlou]

I bought a new 135 headsail for my C30 this year. The boat next to to me is a 30' Irwin and the owner expressed an interest in my old headsails. We looked up the luff dimensions of my 110 and 155 sails and found them to differ by over four feet. Since they both go up to the top of the mast we couldn't figure out why the luff dimensions weren't the same. What am I missing?

 

[oldersalt]

Ummm, just a wild guess, but maybe the masts are of different lengths? I know it sounds crazy but it just might be true. They may both be 30' boats, but they are different boats, by different designers, with different characteristics, including such minor characteristics as sail area (main sail area is .5 height x base), which might suggest different mast lengths. As I say, just a wild-ass guess...

 

[oldersalt]

Oops, you said headsail, not mainsail. Sorry. Well, the same basic argument applies, but the arithmetic for determing the length of the headsail luff is a bit different, and is left as an exercise for the reader.

 

[captcoho]

Tall rig or standard ????
Tall rig Luff = 41.43 I = 43.0'
Leech = 40.1 J = 13.16'
LP = 20.25

My actual 155% Tall laying on the dock,
Luff 41' 3"
Leech 39'10"
Foot 20'10"

 

[drazlou]

Standard rig. Regardless of whatever the mast height is, the length of the furler foil is fixed and if my 110 and 155 both go all the way from the furler drum to the head of the mast the luff lengths should be the same, shouldn't they?

 

[captcoho]

Standard rig. Regardless of whatever the mast height is, the length of the furler foil is fixed and if my 110 and 155 both go all the way from the furler drum to the head of the mast the luff lengths should be the same, shouldn't they?

Yes