Windvane correction

To the editor:

We enjoy your magazine very much and were pleased to see the special attention to recent windvane self-steering article (“Automating a windvane,” Issue No. 108, Sept/Oct 2000). It covered the different ways in which to hook up a small autopilot to a windvane. However, we would like to point out that there was obviously some confusion in the editorial department regarding the photos and the captions that were supposed to explain them. All the photos show Monitor Windvanes - no other brand is shown.

In order to better understand some additional important points on how to hook up the autopilot to any windvane we quote paragraph 4.6 from the new Monitor manual: “If you are making landfall on a small, low atoll, you might have reason to sail on a magnetic course rather than in relation to the wind. You might then prefer to use a small cockpit-mounted tiller pilot hooked up to the windvane. You would use the windvane’s powerful servo-paddle to move the boat’s rudder, but the signal would not come from the wind. If you attach the tiller fitting for the autopilot to the counterweight of the windvane, the tiller pilot will manipulate the counterweight and provide input to the servomechanism. “You could also fabricate a small, short airvane and put the autopilot tiller fitting on the top. The height of the windvane and the design of the stern pulpit will determine the most practical way of hooking up the autopilot to the windvane.” You should be aware that the small cockpit-mounted autopilots push 80 to 100 lbs. If you design a hookup of your autopilot to the windvane, the system should have a safety release that makes the autopilot jump off the fitting it pushes against. If there is no safety system you could damage the autopilot, the windvane, or both. This could happen if the skipper takes over the steering but forgets to disengage the autopilot. “We do not recommend this type of arrangement be used for extensive powering because the servo-paddle will be positioned in very turbulent water from the propeller wash. This will most certainly cause a lot more wear on the windvane than sailing with the windvane in the roughest possible conditions. You can compare it to a filled sail and a sail flapping violently in the wind. Under power the engine is charging the batteries, and, in those conditions, we believe it is better to hook up the autopilot directly to the boat’s steering than putting unnecessary miles on the windvane.”

Scanmar International manufactures the Monitor, Autohelm and Sayes Rig windvanes and the above arrangements can be used for all these brands with some modification. These setups should also work on other windvane models.Finally, we point out that a larger windvane will improve light air performance on any windvane just as a larger sail will drive your boat better than a small sail in such conditions. The Monitor light-air vane has a 60% larger area than the standard airvane. This airvane is far superior in light air and downwind when the apparent wind is very light. If you should decide to make your own light-air vane, it is absolutely essential that the airvane is the right weight. If it is top heavy the airvane sends the wrong signal and the windvane does not work.

By Ocean Navigator