When to reef and change sails for optimizing performance.

[Splashman237]

For a modern boat especially a racer type boat , you can get a set of “Polar diagrams” which give you the theoretical fastest water speed for different wind strengths and sailing angles, from them you can see if you are sailing below the max speed for a particular wind angle and that’s an indicator that either your sails are not trimmed correctly/optimally or you may need to reef .

[Don C L]

This might help:
http://www.cruisersforum.com/forums/...rs-212558.html

[Mabel Page]

Good quality posts folks. I really appreciate your time and expertise.

Russell

[KiwiKen]

Originally Posted by Splashman237

For a modern boat especially a racer type boat , you can get a set of “Polar diagrams” which give you the theoretical fastest water speed for different wind strengths and sailing angles, from them you can see if you are sailing below the max speed for a particular wind angle and that’s an indicator that either your sails are not trimmed correctly/optimally or you may need to reef .

You didn't mention the point of sail in the example you gave, and this can determine at what point one reduces sail.


There are generally trade offs.


Going to windward the optimum angle of heel is that giving the greatest waterline length, because waterline length is a factor in achieving best speed to windward.


As the angle of heel increases, leeway usually also increases, and hence is less efficient in achieving the best speed to windward.


Once the angle of heel is such that the gunnel is frequently submerged and water is flowing round stanchion bases, drag will increase which will effect speed through the water.


In cruising efficiency is not as critical as when racing, when one has to decide whether the speed sacrificed/ time lost while reducing headsail, can be recovered by better performance after the sail change before the next mark.



Polar diagrams are an excellent guide to obtaining best performance under sail on all points of sail over a wide wind range. Sailing on the limit always carries the risk that something may break, and is seldom worth the risk when cruising.

[44'cruisingcat]

On our old boat you'd start losing control in the gusts. Then you knew you should have reefed.