|Topic Review (Newest First)|
|06-17-2007 09:29 AM|
....yawn...what?.....has somebody went and taken me seriously again?
I just love to stir the pot
|06-17-2007 09:23 AM|
Chris..the windex does indicate apparent wind, when moving and true when stoped. (mine disappeared some time ago, new one already on order, want to go up the mast install it??), but the ST60 indicates (well mine used to, but now only indicated apparent due to a faulty wire, according to what Tom found when there) both apparent and true with the boat moving.
Just a side noteChris G I know you know this but this helps others)
True Wind is the wind speed and direction one feels with the boat fixed on a point, that is when its not moving, and apparent wind is the wind direction and speed when boat moves, modified by all the different vectorial changes that occur once the boat moves.
On an closed reaching the apparent wind moves towards the bow, decreasing the wind angle, and the indicated wind speed increases, reading therefore lower tack angle and higher windspeed.
On a wide reach (whatever its called in English), the apparent is also forward, but the wind speed indicated is lower. When we move towards the runing the apparent wind will almost drop as a consequence of the boat moving with the wind.
When I meant 25º it was really true wind. Normally boats will start, under normal conditions at 30 to 32º. I can get just a little bit more. Off course you must understand I can pretty much do what I want with my sails and mast configuration to help.
I have done many runs, almost a year ago when we first started sailing my boat..
We've had many cases, and we did thsat to develp the polars for my boat.
In one instance with 15 knot true wind, we were doing around 4 to 5 knots, at exactly 25º true. The apparent wind was indicating around 18 knots wind speed apparent at 20º off the bow.
Normally in 25 to 30 knot winds, (true), we can sail at 8 knots, and be pointing 25º true. This is around 20º apparent and indicated apparent wind of 35.
Either way, I can still move at 25º apparent or 25º true.
When Tom and Mark were in Portugal, last week, we were doing a relaxed sailing at 20º apparent, with 20 knot winds apparent, and speed over ground was 7 knots and according to my calculation, that is already 29º off the true wind.
|06-17-2007 01:37 AM|
I thought on a windex the arrow pointed at the apparent wind, and the two tails gave your angle relative to that.
A racer tacking thru 90 in 12 knots true at 5 knots is at 32 true. However at 9 bs 10tw and 25 to true the apparent wind angle would be 18.5. The faster he goes the more the apparent wind moves towards his bow and the further he must bear off from the true wind while maintaining the same angle to the relative wind.
|06-17-2007 12:27 AM|
|sailaway21||Actually Chris, Giu has set his windex for true wind. As boat speed increases, his apparent wind increases, and he may be able to point even higher. He has probably set his windex for what he can reasonably expect in light air. Any way you cut the cake, he's a seriously fast herring fisher.(g)|
|06-16-2007 10:12 PM|
|USCGRET1990||....annnnd You Are Drunk....right???|
|06-16-2007 09:50 PM|
|chris_gee||If the windex is set at 50 tack to tack surely that is apparent not true wind, so the actual angle you tack through would be greater by twice the angle by which the apparent wind differs from the actual.|
|06-16-2007 07:44 PM|
Originally Posted by sailaway21
|06-16-2007 07:40 PM|
always the voice of reason, generally spot on the facts, with just a touch of ironic humor.
"slovenia" hmmmm, are you guys in NATO yet? we could use such voices.(VBG)
|06-16-2007 07:11 PM|
Originally Posted by USCGRET1990
|06-16-2007 06:47 PM|
My windex is (was it disappeared mysteriously ) 50º from tack to tack.
25º true. Mind you my boat is set with a 115% genoa, inside shroud genoa track, and barber haulers.
Even at 25 into, it does not decelerate that much. Of course the problem is since she is so wide, pointing performance decreases, thus the smaller genoa, inside tracks and barber. She was built for reach and downwind.
last week with Tom and mark driving, we were doing around 25 to 30º at 1 or 2 knots less than wind. And as soon as Tom veered off wind, she would quickly jump to wind speed or near it.
|This thread has more than 10 replies. Click here to review the whole thread.|