windvane?? questions

[sthomper]

is a windvane essentailly useless or some type of dishonesty??

if it isnt, can it hold a accurate course overnight...provided the sails are trimmed ??

if the wind changes direction by a few degrees how close could a yacht hold its course over roughly an 8 hour period??

additionally, do modern yachts tack/jib with a windvane in operation while one sleeps??

[sthomper]

in a reply to another post i guess i got some clarification. if for example i am sailign across the atalntic on a windvane equipped boat and i go to sleep for 6 hours and of that 6 there is a roughtly a 2 degree northward **** in winds for 4 hours the boat will move approx 2 degrees northward for several miles????? and when i wake up i amy have to adjust course southward to get to the azores??? is that how the windvane is often used??

[rebel heart]

is a windvane essentailly useless or some type of dishonesty??

No. Millions of miles sailed across oceans and seas indicates they are quite reliable.

if it isnt, can it hold a accurate course overnight...provided the sails are trimmed ??

Installed properly, boat trimmed, a wind vane will typically sail a boat provided there's enough wind for the boat to sail.

if the wind changes direction by a few degrees how close could a yacht hold its course over roughly an 8 hour period??

The boat will be held to an angle on the wind. If the wind changes 90 degrees, so will the boat's heading. The takeaway is that generally speaking winds don't change that much, certainly not that quickly, you should be checking your heading more than every eight hours, and the potential for a wind vane to steer you into a beach should be on the top of your mind if you're near coastal.

additionally, do modern yachts tack/jib with a windvane in operation while one sleeps??

A wind vane won't cause you to take or gybe. It will hold you to an angle on the wind.

[rebel heart]

Originally Posted by sthomper

in a reply to another post i guess i got some clarification. if for example i am sailign across the atalntic on a windvane equipped boat and i go to sleep for 6 hours and of that 6 there is a roughtly a 2 degree northward **** in winds for 4 hours the boat will move approx 2 degrees northward for several miles????? and when i wake up i amy have to adjust course southward to get to the azores??? is that how the windvane is often used??

Yes. This is a passage we just finished making a few days ago where 3/4 of it was via a windvane:

http://thekeel.com/PassageEdit.aspx?id=2101

You'll notice the course buzzes around a bit, not staying on a completely straight line. A lot of the adjustments we made were more about running down wind when the waves got steeper. No one's really crossing a big body of water making a constant bearing.

[JPA Cate]

sthomper,

Jim and I sailed the South Pacific for about 18 years full time using a home built windvane for steering. Some people fit windvanes to their boats as backup devices in case their main electric autopilot fails. You have been answered in another thread about watch schecules, so I will not go into that here, except to say that even singlehanders train themselves to waken and check their course. If it had changed, they would re-set the wind vane and sails to return to the magnetic heading they wanted. We used to check the course every 10 min. or so, so that there was no question of spending on the order of 6 hours sailing off course.

[SkiprJohn]

I think it has been explained that the windvane steers a course relative to the apparent wind, not a magnetic course. Also, there should be no time that you'll leave the cockpit for 6 hours since by law (International Rules of the Road) you are required to keep a proper lookout at all times. So, you'll be checking your course a lot more frequently than 6 hours. When the wind changes direction enough to put you off your course more than a few degrees you'll have to reset your windvane or live with the course change.

[RainDog]

http://www.selfsteer.com/windvanes101/index.php

[Reefmagnet]

Just to state the bleedin' obvious, changes in wind speed and boat speed also affect apparent wind angles.

[gjordan]

No windvane steers a perfect course, no auto pilot steers a perfect course, no human steers a perfect course for more than an hour or two. Crossing oceans is all about fatigue. If you dont have some type of self steering and you are a small crew, you will learn all about fatigue. Unless you have a large crew, dont ever think about 6 hours undisturbed sleep. It is not reality. Read a lot of the classics and then you will see a better picture of passage making . Good Luck. ______Grant.