One of the reasons for this could be that sailing, in its traditional form, is a skilful, complicated process which requires a lot of attention from the crew and constant monitoring of wind strength and direction to make acceptable used of the wind's power.

It also requires a considerable amount of physical effort and activity from the open decks of a vessel.

Crews have to suffer the effects of cold and wet out in the open. There are inherent dangers, such as being swept overboard, accidents with ropes, being hit by booms and many other hazards. Every year worldwide there are hundreds of cases of injury or event death from these hazards. Nowadays, when there is the option of using motor power instead of wind power, it is hardly surprising that using wind power is  unattractive to all but adventurers and those that take pleasure in conquering hardships as a challenge.

How much easier it would be if we could devise a system that eliminates all the foregoing disadvantages of using wind power and still give the opportunity of using free, sustainable eco friendly propulsion system either as a main source of power, or supplementary to reduce fuel consumption and pollution from ship's engines.

This is why the concept of Windthruster Units, which work automatically, and with almost zero attention has been developed.

Autonomous Windthruster Units Described

The Units have only one external control, a power lever for forward, neutral and reverse (and all intermediate settings) and the units can be made in various sizes for different sizes of boats and simply bolt on.

The system has, instead of a cloth sail, a solid (but very light) wing similar to that of an aircraft. This wing provides the thrust to drive the boat, and with a coupled flap at the trailing edge, can give up to three times more thrust than a conventional sail of the same area, with a considerable reduction in drag also. The wing can rotate freely about a vertical axis 360 degrees.

Controlling the wing unit could not be more different than that used with a conventional sail.

Any wing or sail needs to be adjusted to the correct angle relative to the the wind to provide the required thrust to drive the boat.

We could, of course, provide a manual system as used in conventional cloth sails, where the helmsman must keep a constant eye on the wind direction and pivot the wing accordingly all the time, but it will be almost impossible for any person to react fast enough and in the right degree and with the speed that is necessary, and this is quite apart from the fact that there would have to be someone on watch 24 hours a day to perform this duty.

With a Windthruster unit, this is done automatically in the same way that an aircraft's wing is kept at the correct angle of attack by another surface some distance behind it, the tail. Most planes could not fly if their wings were not controlled in this way.

So it is with the Windthruster unit; a tail is mounted some distance behind the main wing, and by varying its angle, it automatically keeps the wing at the correct angle and instantaneously and automatically reacts to gusts and any changes in wind direction much more accurately than could be done with a manual system. The tail is adjusted to the correct degree and after that, the wing and tail unit follow the wind automatically.

The Complete Automatic Thrust Solution

In order to get a complete thrust solution for all conditions and directions, two further things have to be adjusted.

1. For best performance the angle of attack of the wing, governed by the angle of the tail, needs to be varied according to what angle the wind is coming from, for example: whether the wind is coming from the side of the boat (beam wind) or whether the wind is coming from more ahead of the boat.

2. If the wind comes from the other side of the boat, the tail needs to be adjusted to a mirror image of where it was before causing the wind to work from the other side, to enable the wing to still push the boat forwards (automatic tacking).

These two points are dealt with by the non-electronic (patent-applied for)  features of the Windthruster system, and result in a system where there is only one control, a "power" lever with forward, neutral, and reverse with every other setting in between.

The Auto Control Unit (the drum shaped module in the picture) automatically adjusts the tail for whichever side of the wing the wind is coming from, and to the correct amount for the heading of the craft. In this way the system is completely self tacking and self tending. This unit is a simple system and works mechanically and not electronically, therefore doing away with the need for an electric power supply and another possible source of unreliability.

Using the System

There is one lever for operation with three main positions: Neutral, Forward and Reverse. The lever is pushed forward to go forward and pulled backwards for reverse, naturally in between these two is the neutral position.

Neutral is a "parking" position with the tail at zero angle of attack and the wing/tail assembly simple weathercocks around according to the wind direction.
In Neutral, because of the perfectly streamlined section of both the main wing and the tail, there is less drag than there would be from a normal mast, so it is perfectly safe to leave the Windthruster unit, (unlike a conventional sail), up and in place in all conditions.

Forward and Reverse are then used to move in the required direction.
There is no further control required to operate the system, and all the complications and operating procedures of a conventional sailing rig are eliminated.

There is no need for the helmsman to change tack manually or adjust the angle of attack.
There is no need for the helmsman to even be aware of what direction the wind is coming from.
Everything is dealt with by the Windthruster Auto Control Unit.
This has been achieved previously by using electronic sensors and computer systems, but the patent applied for Auto Control Unit is entirely mechanical, cheap and simple to make and repair, needs no power supply and will robustly stand up to severe marine conditions. To see how it works, click here.

Windthruster Units will work 24/7 without attention or adjustment in varying wind strengths and directions.
The wind may drop to nothing (for example, in the night), but when it rises again the unit will automatically set itself to drive the boat without external attention and on the correct tack.
Should conditions become extreme the power lever setting can be reduced or set to neutral which is equivalent to taking down the sails on a conventional sailing boat. This can be done manually or automatically using a drag device that senses wind strength that pulls the lever towards neutral.

"Self-trimming" is it a well-proven concept? click here for details