wind vane

[musolmar]

I am a "newbe" and am having trouble reading the wind once underway. Living on the Outer Banks, NC, the wind is notorious for changing direction. I sail soundside ( not open water) and the wave action is influenced by wind, current and tides. So sometimes it is difficult to see the change in the wind direction from the waves. There aren''t many sailboats, no smoke, etc - the usually things the "sailing books" tell you to look at to help read the true wind. I saw a wind vane for a dinghy at West Marine. Would a wind vane help my sail trim? I''m not exactly sure how to read it, since it shows apparent wind.

[jbanta]

Apparent wind is what you will be concered with most of the time while you are sailing. True wind is ok but you need to know what the wind you are experincing is doing. A wind vane will tell you what point of sail you are on so you can make the best of your sail trim. It will tell you if you are coming into Irons. Even on a small dinghy a vane will be of great help.

[musolmar]

I do have to know what direction the true wind is so I can get on the correct point of sail. Then the wind vane will tell me that I am on the point of sail - is that right. For instance. If the is comming from the west and I am on the close reach, then the windvane will be about 60 degress off to the Northwest if I''m on a starboard tack? Is that right?

Then I can turn the boat into the wind occassionally, watch for the windvane to come over the centerline of the boat, then I will be able know the true direction of the wind. Correct?

Or still confused?

[paulk]

You''re still confused. If the wind is from the West, and you''re on a close starboard tack reach, the masthead vane will be pointing more Southerly than Northerly. It might be easier to visualize if you imagine a windvane on your car in the same West wind. Parked, you figure the wind is blowing about 15 knots, and you see the vane is pointing due West. You head off South (on starboard tack), and as your car moves forward, you notice your windvane isn''t pointing due West any more -- it''s shifted a bit to the South too. When you speed up onto the interstate, still headed South, the windvane will be pointing almost due South because the forward speed of the car (65mph?) pretty much overcomes the West wind, When you stop for gas, the vane will point West again. On the way back, headed North,(on port tack, now) the vane will again shift forwards, to the North, despite the steady 15 knot West wind, because of the car''s movement.
The same thing happens on your boat, though perhaps not as dramatically. As you go faster on ANY point of sail, the apparent wind goes forward. It is important to know where the apparent wind is coming from, because it is the apparent wind that your sails are using to move the boat. That''s why iceboats go off on 50 mph "reaches" with their sails sheeted in tight. They start out parked in the true wind, and head off on a reach, same as you & me, with the boom off their quarter. They then get going faster, so the wind moves forward and blows a little harder, and they sheet in a little bit. This gets them going faster, which increases their apparent wind still more, so they sheet in some more, and go still faster. You & I have hull speed keeping us from doing this, but planing dinghies work on the same principle.
In any case, a windvane would help give you an idea of how to trim your sails, depending upon
your heading. It''s important to realize that it''s the relative directions of the wind and the boat -- the apparent wind -- which is crucial. Knowing where the true wind is coming from -- heading into it to see where it is -- is nice, but it isn''t going to get you anywhere.

[musolmar]

Thanks, I guess the best thing to do is mount the wind vane and see what happens.

[BarryL]

Hello,

Before you mount the windvane (which is a good idea) you can tie some light material, like twine, old casette tape, etc. to the shrouds or stays. That will show you the wind direction too.

Good luck,
Barry

[musolmar]

I found how to make a wind vane with a coat hanger, cassette type and duct tape. Took 5 minutes and cost about 10 cents. I took a link (windline sails) on www.sunfishclass.com.

[mdougan]

I think you''re making it more difficult than it needs to be... you don''t really need to think about what direction you are heading or what direction the wind is coming from (direction as in East, West etc...) what''s most important is the direction relative to the direction you are pointing.

Think of the dial of the vane as the face of a clock... with the line pointing to the bow of the boat as 12:00

Watch where the vane arrow points, if you''re between 10 and 2, you''re probably sailing too close to the wind. If your vane is pointing at 6:00 (wind directly aft), you''re about to gybe. Anything else will just tell you whether your sails should be sheeted in close (8:30-10:00 or 2:00 - 3:30) or out (3:30 - 6:00 or 6:00 to 8:30)... and you can then adjust your sails accordingly.