How sails are designed.
Bloged by Tom
I was recently asked about sail design by an Italian magazine. Unfortunately due to the timing I was only able to give the most cursory answers. Having thought about it a bit I decided that the people who buy HSM products deserve to know a bit about what goes into them. I cannot fully explain the designs or how they are created (top secret!), but I can give you an insight.
Take a piece of paper. You can easily curve it in one direction or another. It is a two dimensional object and can be made to conform to any 2D shape. Piece of cake. Now take that paper and twist it. It does not want to do it does it? All you get are giant wrinkles. This is the problem the sail designer faces – making a 3D object from 2D materials. Not only that but we deal with dynamic systems, that is to say they are constantly changing. One last spanner in the works is that what a sail wants to do naturally is the opposite of what you want it to do. A little tricky.
So it seems impossible, yet we have come so far. Modern sails are engineering feats no doubt. The windsurfing environment is so complex with so many variables that it is impossible to model. So how is it done?
I can’t speak for other designers, but here is how I do it. I look at the sail as a complete surface. I look at the whole system rather than individual isolated points. So if I change anything it changes EVERYTHING. Imagine this, big soap bubble. If you touch it, it will adhere to your finger (if it does not pop!) and you can manipulate it. You only move one point on the bubble but the entire bubble changes. I treat it as a 4 dimensional object – 3 spatial dimensions and a tension dimension. They are all related and any change in one causes a change in the others. Understanding tension in a sail is the key to understanding how a sail shapes and how a sail performs.
Understanding the mast is the other side of the equation. The mast is super critical as it dictates how the sail will be tensioned under dynamic conditions. Use a mast the sail was not designed for and who knows what the sail will do. Most people don’t seem to notice but sail designers cringe when another mast is used. Look at it from our perspective – we’ve been tearing our hair out to eek out meager gains in performance this last year, and some kook takes the sail and rigs it on a mast that sets the performance back 5 or more years!
Anyway, that was just shaping, we put the same effort into material selection, durability, pricing, quality and many other factors.
When you buy a sail from Hot Sails Maui, you are buying it from people who have windsurfed for a very long time, and have put everything they know into the sails. You are getting the very best in performance, durability, quality and price. To be honest we do it for ourselves, so we can have better sessions, ‘cause it’s what we do. You just happen to benefit!
I was recently asked about sail design by an Italian magazine. Unfortunately due to the timing I was only able to give the most cursory answers. Having thought about it a bit I decided that the people who buy HSM products deserve to know a bit about what goes into them. I cannot fully explain the designs or how they are created (top secret!), but I can give you an insight.
Take a piece of paper. You can easily curve it in one direction or another. It is a two dimensional object and can be made to conform to any 2D shape. Piece of cake. Now take that paper and twist it. It does not want to do it does it? All you get are giant wrinkles. This is the problem the sail designer faces – making a 3D object from 2D materials. Not only that but we deal with dynamic systems, that is to say they are constantly changing. One last spanner in the works is that what a sail wants to do naturally is the opposite of what you want it to do. A little tricky.
So it seems impossible, yet we have come so far. Modern sails are engineering feats no doubt. The windsurfing environment is so complex with so many variables that it is impossible to model. So how is it done?
I can’t speak for other designers, but here is how I do it. I look at the sail as a complete surface. I look at the whole system rather than individual isolated points. So if I change anything it changes EVERYTHING. Imagine this, big soap bubble. If you touch it, it will adhere to your finger (if it does not pop!) and you can manipulate it. You only move one point on the bubble but the entire bubble changes. I treat it as a 4 dimensional object – 3 spatial dimensions and a tension dimension. They are all related and any change in one causes a change in the others. Understanding tension in a sail is the key to understanding how a sail shapes and how a sail performs.
Understanding the mast is the other side of the equation. The mast is super critical as it dictates how the sail will be tensioned under dynamic conditions. Use a mast the sail was not designed for and who knows what the sail will do. Most people don’t seem to notice but sail designers cringe when another mast is used. Look at it from our perspective – we’ve been tearing our hair out to eek out meager gains in performance this last year, and some kook takes the sail and rigs it on a mast that sets the performance back 5 or more years!
Anyway, that was just shaping, we put the same effort into material selection, durability, pricing, quality and many other factors.
When you buy a sail from Hot Sails Maui, you are buying it from people who have windsurfed for a very long time, and have put everything they know into the sails. You are getting the very best in performance, durability, quality and price. To be honest we do it for ourselves, so we can have better sessions, ‘cause it’s what we do. You just happen to benefit!
posted by Jeffrey, Glenn and Tom at
2/06/2008 10:01:00 PM
5 Comments:
Really nice read. I hope that was pt 1 of 3 or 4 :)
Have you heard of developable surfaces? It's the kind of surface which you can get from bending a flat one. The cylinder is the fact example, but they can in fact be very complex looking. The way you describe sail design is a bit like the art of "almost developable" surfaces. Locally its developable but globally is not.
One comment: since all posts are by Jeff, Tom and Glenn, it would be nice to know at the beginning of the post who's the person posting. Unless, of course, you can deduce it by the fact that he's getting married to Anne...
Great post, whoever it was.
Ok, so I do most of the posts, so if I forget to say it is me - Tom, then assume I wrote it unless it says otherwise. I will try to encourage Jeff and Glenn to post more.
Nice write up!Keep 'em coming!
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