Roach?

[Quoddy]

I have heard it said that most of the lift from the mainsail occurs in the forward half. As you move towards the leech the lift goes down and the drag goes up. So what’s the statement “it’s a powerful main with a large roach” about?

 

[robertsapp]

I have heard it said that most of the lift from the mainsail occurs in the forward half. As you move towards the leech the lift goes down and the drag goes up. So what’s the statement “it’s a powerful main with a large roach” about?

If you'll think about it, I believe you'll discover you've already answered your own question. If as you say the majority of lift comes from the forward half of the sail, well, doesn't a full roach main have a much larger "forward half" than one with a straight or concave leech?

 

[kloudie1]

And there is that downwind thing.. where ya want as many square feet as you can stand.

 

[Joe]

The power comes from the back half of the main.... that's why it's so important to have leech tell tales. A larger roach adds more power.

 

[Quoddy]

Power,max draft or leech?

Thanks. I thought I got it. Adding to the leech isn’t so much affecting the leech as it is lengthening the chord. This would increase the size of the area of maximum draft, which is 40-50 percent back from the luff.
Now I just read that the power in the main comes from the leech. I thought that the outhaul was a primary power adjustment because of it ability to change the depth of the draft which is 40-50 percent back from the luff. I must be missing something.