The Vortex Sail, Variable Geometry Proa

by Malcolm Smith

Photos by Jane Smith

Model 1A


Model 1A, a free running model used to test the Vortex Proa principle


Model 1A on the water

Model 1A was approximately 400mm long and had a main spar length of 800mm. Attached to the ama, it had a hook shaped hydrofoil designed to lift the ama out of the water to a certain point, then dig in if the ama tried to lift any further.

The cross beam was able to swing so that the sail and hydrofoil could be correctly aligned for self steering. The single cross beam rotates on a shaft on each hull. Wires on ether side of the cross beam maintain the hull alignment.

The model showed some amazing bursts of speed, but because of its small size and self sailing nature (lack of human intervention), would tend to be blown completely out of the water at times.

From observing this model I concluded that there could be some merit in the persuing concept further.

Model 2. Photo's and Notes