Hi jack,
Spin out is caused by a number of problems.
1. The fin.
If the fin is too big for the conditions it will create too much lift. This will make the board rise too far out of the water ,the nose lift, and make the ride totally uncontrolable. Spin out normally occurs just after as air gets around the base of the fin and it loses all traction on the water.
If it is too small, you will notice the board spinning out at lower speeds, as you are accelerating. The board will just loose grip on the water and go side ways.
To solve these problems make sure you have the right size fin for the board/conditions. Most wave boards will come with small fins to aid manouverability, so will suffer from the second problem. Most freeride boards come with larger fins so will be affected by the first.
For example on my wave board(JP Wave 80l with a 5.0 m) in 20knts I'll use a 22cm fin.
For the same wind strength on a slalom board with a 6.5m sail I'll have a 30cm.
2.Technique
The other reason you will spin out is lack of anticiaption sailing over chop,waves etc. Your legs are your intelligent suspension system, so you have to push the board in and out as you ride over swell so the board is always in contact with the water. If you get it out of sequence, the board takes off, and the fin will spin out.
Hope this all helps.
Simon
www.gowindsurfing.com
