MacGregorSailors.com

Will the rotating mast on a affect a nasa wind system ?
Has anyone fitted such a system ?
Was there any problems ?

I have the Raymarine ST40- http://www.raymarine.com/ProductDetail. ... RODUCT=425
This works well however the wind direction is not accurate because of when the mast rotates, it changes the baseline measurement of the sensor. I use a Davis Windex for wind direction and the RAymarine ST40 for windspeed. If you keep the mast from rotating or figure a way to mount it forward on a spreader it may work ...but I think that would be counter productive for the benifit you would recieve.

We have our ST40 rotovectra mounted on the mast support arch. Seems to get proper readings in all directions. I was concerned that when to the wind it would be inaccurate. Doesn't seem to be the case. Knowing the wind speed has really improve my sailing as I can tell how well the boat is performing compared to wind. Having fairly accurate direction means not having to look up to the windex. (difficult to see around the bimini)

I also looked at a furumo unit with built in compass (compensates for mast rotation), but it was too expensive compared to the ST40.

I also have the ST40. Not mounted to the masthead due to rotating mast as already stated. Readings are reasonably accurate. It's a great companion to an autopilot, allowing the pilot to lock on to any wind angle and adjust to wind shifts.

Here's how I did mine. There's a potentiometer in the base of the mast that feeds the mast angle into the system for correction: http://www.macgregorsailors.com/modt/index.php?view=701

Since the mast likely rotates the same angle after a tack, you could probably have two different scales: one for starboard tack, and one for port tack; and read the appropriate one to get your apparent wind. Perhaps these could be transparent overlays on your display.

Dan