Vane size for windvane

[Ribe16]

Hello everybody.

I just bought a boat that has a windvane installed, but couldn't find the vane for it anywhere. If I make one myself:

1. Which materials should I use and which ones avoid?
2. What would be a good size for a 8.5 ton 37 feet full keek boat?

Thanks a lot.

[Celestialsailor]

It would probably be helpful to know which windvane manufacturer it is as well as what system...trim tab, servo pendulum, ect. Pictures also.

[Ribe16]

Originally Posted by Celestialsailor

It would probably be helpful to know which windvane manufacturer it is as well as what system...trim tab, servo pendulum, ect. Pictures also.

It's a Fleming (out of business), should be Global Offshore 401 or 501
Manual only says use 4mm birch marine grade plywood for vane, no measurements.

[Windpilot]

My windpilot pacific of very similar designs vane is approx 34" × 8" of the material you mentioned.
Boat Size, weight has nothing to do with it.
It needs to balance the offset weight where it attaches. The weight of the vane most important, too heavy vane fall to side on its own. To light could lose light air sensitivity.
Size wise, tall is good but with clear air and good wind anything close to that size would work.
I'm 2 days out of Hawaii to CA writing this watching mine work.
Make a couple different sized ones.

[robert sailor]

Wind pilot is correct in proper balance is required on the vane. I used a Fleming for several years and it did a great job. If my memory serves me the Fleming had the counter weights on threads so they can be adjusted. It’s not a bad idea to attach a long ribbon on the trailing edge of the vane as that excites the vane in lighter air and can improve performance. Servo pendulum vanes are manufactured differently even though they all operate using similar principles and the vane sizes vary from different manufactures…for example the vane size of the Cape Horn vane is half the size of most others and that simply demonstrates how little friction there is in the system. Wind pilots numbers are an ok place to start, it’s not rocket science.

[wholybee]

It is less about the size, and more about balance. It needs to always return to vertical on it's own. A larger vane works better in light air both because it is larger, and because being heavier it takes less wind to overcome the counter balance.

The Monitor ships with 2 sizes to experiment with what one works better. So if making my own, for any brand, I would do that, make 2, one that seems a bit small, and one that seems a bit large. Then adjust them if necessary.

[Celestialsailor]

Originally Posted by Ribe16

It's a Fleming (out of business), should be Global Offshore 401 or 501
Manual only says use 4mm birch marine grade plywood for vane, no measurements.

Thanx for the update. Windpilot hit the nail on the head. balance is everything. When making the air vane, start with it longer and trim down. That said, disconnect the rod from the "bellcrank" which is the mechanism that rotates the water oar. Being too long, it should just flop over to one side or the other...hence out of balance. here is the trick with each manufacturers design...some have adjustable counterweights, others do not. The trick is to make it sensitive by making sure it stands on its own but not too sensitive. Also varnish or paint the air vane so it does not warp.