Sustainable Free Energy from the Wind

Development of a self-trimming automatic wingsail system

By Peter Worsley

Page three (Sliding cam tail control)

The wing and tail assembly pivot freely about a vertical axis.

As the rig rotates the angle of the tail is regulated by followers bearing on a circular cam
which does not rotate with the rig.

The cam can move from a concentric position with the axis of the wing and tail assembly
or can be moved either way to an eccentric positions causing the tail angle to change.

What can it do?

It allows the rig to be self-trimming and to operate autonomously without control necessary by the helmsman.


Whatever direction the wind comes from, the rig will adjust itself to provide optimum forward or backwards thrust to the boat.
The helmsman does not need to have control of this, the rig will do it automatically. However he/she can lessen or increase the effect of the automatic control from zero to full thrust either forward or reverse. The helm does not need to know what direction the wind is coming from. He/she only needs to steer the boat and adjust the power in the desired direction. So the only control necessary is a lever which works exactly like the throttle on a power boat.


For Patent Application click here

Sliding Cam Tail Control demonstration of how it works

Testing on Barton Broad (Norfolk UK)

Early Adopters

Dellencat - Nasviken Sweden - used the system on a Nash 20 sailboat

Skip Johnson boat builder  in Texas USA
used the system on experimental proa "Nomad"

Click for Dellencat Website


Comment from Dave Culp ( A leading member of the Amateur Yacht Research Association)

Worsley’s tail boom control. This is not new, but his utter simplicity in making it work is. His system is 100% mechanical—no computer, no electricity, no hydraulics. Everything built of cheap DIY/hardware store parts. The setting mechanism is set and forget, the boat self-steers a compass course with wing self-adjusting forever (as long as the batteries for the rudders don’t go flat!) The tail is the “throttle” and, if set on low speed, will bravely and simply drive the boat—through hurricanes. I recommend reading his website carefully and watching his video—the one showing how the mechanism works—a dozen times.

Summary of the advantages of the system

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P. Worsley 2013/2022