Wind vane self steering with a mizzen mast?

[Ross D]

I am posting on behalf of a friend who is refitting a 43 foot wooden yawl. He was planning to transfer the wind vane stelf steering system from his other yacht but the boom of the mizzen mast would foul the vane.

The wind vane system is a complete transom hung rudder system which he built himself from plans (master carpenter) many years ago and it works very well.

Does anyone know of a solution to the problem?

Many thanks

Ross

 

[barnaclephill]

The photo attached shows a wind vane on top of the mizzen mast. I think the mast must have been hollow steel. I've never spoken to the owner, just photographed his boat.

Any mizzen sail near the vane will create turbulence or at least a change in airflow direction. The mizzen boom would likely cross paths with the vane's aerofoil.

The easiest way out of that might be to control the vane with a small autopilot in lieu of the aerofoil. The vane mechanism and hydrofoil would remain, saving electric power. Thus the autopilot would, via the top linkage, only power the movement of the vertical push/pull rod, and the water (speed) would transmit power via the hydrofoil to the tiller.

That would mean both an autopilot and a windvane mechanism, but sometimes the mizzen might not be used, and the vane's aerofoil could be used, if the mizzen boom were lashed.

Otherwise, page 36 of "A world of my own" (Robin Knox-Johnston) and other photos shows aerofoils on both the port and starboard side, to avoid the mizzen area.

 

[Bajansailor]

Have a look at these photos of Stormy Weather - she is an S & S yawl, and she did 40 transatlantics steered most of the way by a trusty Aries on the back (with lines going to the tiller).
http://www.stormy.ca/marine/album.html

OK, one had to remember to 'reef' the vane before tacking or gybing with the mizzen up, but the vane worked very well on all courses up to a beam reach, even with the mizzen up.

 

[TerryMac]

We sail an Oyster 39 ketch with Hydrovane self-steering and have no problems at all. If you are downwind then the boom of the mizzen is let out (ie downwind of the vane) so it doesn't effect the movement of the windvane. We sometimes tie a "preventer" on the mizzen boom to stop the boom accidentally flipping over and wiping out the vane. Just don't forget to remove the vane when you are gybing!

If we are going upwind we don't use the mizzen anyway so no problem there. However, if you do use the mizzen upwind then I have read that with the mizzen sheeted hard in you can set the vane to only use the weatherside of its movement by biasing the main rudder.

Hope this helps

Terry

 

[oldvarnish]

TerryMac above is dead right. I had a Hydrovane SS on the back of a ketch and it worked fine. It doesn't matter how much the sail deflects the airflow because it's constant and you adjust for it.

I used to top up the mizzen boom when tacking or gybing so it didn't hit the vane. Going upwind, the mizzen doesn't do much for you anyway so it's not a problem.