Sustainable Free Energy from the Wind

Development of a self-trimming automatic wingsail system

By Peter Worsley

Page two (Fullsize testing)

To test the wingsail control systems in a bigger size I used a Hawke "Surfcat" beach catamaran which is approximately 4 metres in length.


Early version


Later version

Several different ways were tried to control the angle of the tail to enable self-trimming. To allow the 15 degrees movement either way for either tack.

Manual cable control

Left Tack

Right Tack


The helmsman only needs to move the lever to point in the direction the wind is coming from.
The tail is adjusted through the cables.

As this was a cable system the rig could only rotate 90 degrees either side, as in the model system on the previous page

Manual Radio Control

Allowing the rig to rotate through 360 degrees is a better option, but this is not possible with  the direct mechanical connection.
The next step was to make the connection by radio - allowing the rig to rotate anywhere it likes and to pass over the bow of the boat.



Radio Control Box



Sailing using the radio control connection

This was a good system and it worked well. It was the first time 360 degree rotation of the rig was possible. But the helmsman
still had to manually adjust the tail on the control box. I felt another system with completely automatic control was possible.

Next Page - The patented sliding cam control system.



P. Worsley 2013/2020