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Old 22-09-2015, 09:47   #1
tat
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Wind indicator

Hi. I want to buy a wind indicator. I wonder how it works when I'm moving along. Or do I have to stop and take the direction, and then there is the wind speed I will need.

Can anyone explain this to me? I have never used one.

Cheers.
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Old 22-09-2015, 13:18   #2
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Re: Wind indicator

Hi.

Simplified:

Your boat sails with a wind which is the combination of two vectors.
One is the direction and speed of your boat moving through the water.
The other is the true windspeed and direction of the true wind at your momentary location.
The force parallelogram results in a vector moving your boat.

This is the direction your onboard windvane shows.

More complicated instruments can calculate the individual components as well and can even take drift and the like into account.

Have fun!
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Old 22-09-2015, 16:30   #3
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Re: Wind indicator

A wind indicator shows "apparent" wind speed and direction - i.e. the speed and direction that it feels like on the boat. This is the combined result of the true wind and the movement of the boat. That is the important one for sailing because it is the apparent wind that determine the forces on the boat and sails.

If you know your boat speed, you can calculate/guesstimate the true wind speed and direction (if you are sailing into the wind, subtract most of your boat speed from the indicated speed - if you are sailing downwind, add the two together - on a beam reach, they are fairly much the same. The real wind direction will be further aft than the indicated wind direction)

If you have the wind indicator connected to other instruments such as a boat speed indicator or GPS, you should be able to press a button on the indicator display to switch between true and apparent wind.
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Old 23-09-2015, 06:27   #4
tat
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Re: Wind indicator

Franziska and StuM, thank you for those replies. You have cleared that up for me. So the windvane with a wind speed indicator will give me the apparent wind, and this is what I need to use to calculate leeway.

I have a digital hand annenometer which I was thinking of using for wind speed, and then a flag for the direction. Maybe i'll still do this, but I now know it is the apparent wind that I will plot. Thanks very much.
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Old 23-09-2015, 10:55   #5
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Re: Wind indicator

Most welcome!

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Old 24-09-2015, 07:05   #6
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Re: Wind indicator

Franziska, Thanks !!!!!!!!!!!!!!!!!!!!!!!!!!

Just bopught a windvane, a hawk for 22 quid. Thought I'd give it a whirl.

Checked those links for Ladyrover, etc. Liked the music. Bet you like this https://youtu.be/b9xBAtCsCTQ, and what a belting video....I love that kinda video. Bet they shot it in half a day flat, but such creativity. It just all works.
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Old 26-09-2015, 09:25   #7
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Re: Wind indicator

Tat

I believe you will need a bit more than that to calculate leeway. For myself I would use a good compass and a GPS. Steer a magnetic course and plot on a paper chart where you should be in say an hour on that course. Next, get your GPS position and plot it. The difference can be measured on the chart. This takes into account not only wind but currents also.

The detailed method can be found either in a decent nav book or do a web search for "set and drift".

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Old 26-09-2015, 17:56   #8
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Re: Wind indicator

Quote:
Originally Posted by cabo_sailor View Post
Tat

I believe you will need a bit more than that to calculate leeway. For myself I would use a good compass and a GPS. Steer a magnetic course and plot on a paper chart where you should be in say an hour on that course. Next, get your GPS position and plot it. The difference can be measured on the chart. This takes into account not only wind but currents also.

The detailed method can be found either in a decent nav book or do a web search for "set and drift".

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Thank you for that advice. I will read about set and drift. I had planned to plot fixes and estimated positions as I went along to each waypoint, doing my best guess. The tidal stream info I expect will be accurate enough, but then the leeway. My boat is light and really catches the wind, so I expect it will need me to make a wide allowance, and also I will be travelling slowly, so the effect will be even greater. But my radio has GPS, and also stores input waypoints and nav info to them, SOG and COG and bearing, so I was going to plot the GPS readings on the chart, too.

I have been trying the hand-held anenometer. It gives wind speed in mph, both the average and highest, and also gives the wind on the beaufort scale graphically, and I think this will help a lot.

Of course, it all needs experience, and I don't have that yet, so I'll do a bit of trial and error to guage job.

I'm glad I am thinking along the same lines as you with plotting and using the GPS as regards leeway. I will always plot on a paper chart as I go along. If the GPS went down, or some human error which I trusted to, it would be a very different game. So dangerous. I don't really like the sea. I'm scared of it, I suppose, in all truth. I don't like anything dangerous. I'm not an adrenaline junkie. I think it is a challenge that I really need to accomplish, to sail and navigate competently and safely. I nearly drowned once in the sea. I got tired and just knew I didn't have it in me to get to shore. But fortunately I had a snorkel so I could float and take a breather. So I have a lot of respect for water.

Anyway, cheers.
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Old 27-09-2015, 18:03   #9
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Re: Wind indicator

Tat,

I learned about set and drift or its equivalent in flight school and for my USCG six pack license. To tell the truth, with modern electronics, I have never needed those calculations. It's nice to know how but kind of old school.

On the boat I set my course and go. After a while, I check my position on GPS. It shows me how much I'm off course and in which direction. Seeing that I adjust course a bit to compensate. The manual method is fine but winds and currents are constantly changing. Unless you are within sight of shore to take compass bearings it's going to be difficult to place your actual position versus your dead reckoning position with any accuracy.

The idea of keeping track of your position on a chart is a good one. For one thing, if you lose the electronics you will have a good starting point for dead reckoning for the rest of your trip.

Go ahead and learn, it doesn't hurt. Kudos to you for even thinking of it.

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