# Wind pressure on a sail boat

1. Mar 15, 2013

### jacques dichi

Hi forumers,

I've got a question,and of course all proper answers are welcome,
I think however a sailboat designer/engineer would quickly know
I'd like to know what is the pressure/push of a 10 mph (16 km/h)
wind on 12,000 sq.mt. surface ,and how to figure this out if I change
the parameters ?
Thks. & Happy Easter
J.D.

2. Mar 18, 2013

### Staff: Mentor

You can use Bernoulli's equation to calculate the stagnation pressure at that wind speed.

3. Mar 19, 2013

### jacques dichi

Thk. u Russ for yr. reply I'll try bernoulli as suggested - if he fails me - I'll come back to u

4. Mar 23, 2013

### sci-phy

Hey,

It depends on the surface you are talking about. If it is a sail, then it can deform so that the velocity of the wind is practically zero on the sail surface. So Bernoulli's principle would hold good. But if it is a rigid surface, the wind will get deflected and the force is based on Newton's 2nd law. Besides, this value also changes with the direction of wind and speed of the boat(or surface) and compression of air.
Do let me know if you want a general equation for the same :)

5. Mar 23, 2013

### jacques dichi

thks. for your answer. - I think according to it I might have misled a few people with the phrasing of the question or my comparison - sorry for that.
What I have is a 120m. span 3 wing wind turbine -approx. 12,000 m^2 surface - it does not deform like a sail and it is not rigid like a wall although when rotating it could be considered as such - and a 10 mph wind.
If I decrease the surface,how have I got to increase the wind in order to obtain the same "pressure/push" ?
Pls. bear with me,
Thks.