I have been learning quite a bit about sailing from this site and about what makes the land sailers sail. I have made one LLF mini with a tyvek sail, all from information and plans that I got here.

While I am learning a ton, I still feel like there are a lot of gaps in my understanding of how a sail functions and how to go about making a good all-around sail.

I was hoping that some of you could help me fill in some of those gaps.

This is what I know (or think I know) about land yacht sails:

1. Flat is Fast
2. deep sail to start for low end power and then flat when sheeted in for speed
3. When sailing, set sail to the apparent wind

These are some things I am hoping to learn:

1. Why is flat fast?
2. Can I create adequate camber by curving luff only or do I need to broad seam?


I am also including a couple of illustrations here to show what I understand about broad seaming. The first picture shows how I would cut the pannels, the second shows my understanding of where the depth in the sail would be created (red circled areas) when sewn together.

As always, appreciate the input
Bob