Following up.There was a thread a month or so ago relating to apparent wind that talked about the apparent wind changing as the boat picks up speed. That didn't make sense to me at the time but by this logic of vectors, as the boat speed increases, the apparent wind angle would move away from the boat allowing one to sail tighter into the wind. By experience, that is what happens which would be explained by the vector thing.I guess.
Jim _____ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, October 01, 2008 8:50 PM To: [email protected]; [email protected] Cc: Jim Bernstorf Subject: Re: catalina27-talk: into the wind Jim, Apparent wind is the right answer. Do you remember high school physics and vectors? The actual wind is moving in a given direction at a given speed. So is your boat. If you add the two vectors together, that is your apparent wind. A simple example (I think), if the actual wind is blowing at 5 knots directly abeam and your boat is moving at 5 knots, the apparent wind will be 45 degrees off your boat direction toward the wind. Of course, I'm ignoring that your boat really won't be going straight ahead, but sliding sideways a bit. Many of us learned to judge the wind by the masthead and telltales on the shrouds, but a captain taught me a while ago to observe the direction of the wave swells on the water. They will be perpendicular to the actual wind. Sorry, can't address the 150 vs 120 genoa question. Fair winds, Ken -------------- Original message -------------- From: "Jim Bernstorf" <[EMAIL PROTECTED]> OK.it is quiet so let me pick your collective brains. I just hoisted a friend of mine nearly 40' to the top of my TR mast to install a wind direction twirly-do (note the technical terminology). The box had a template to set the aft pointing guide things ranging from about 55 to 75 degrees. I set mine at 60 since I didn't know the right answer. Now, it has been my understanding that most boats cannot sail effectively in the 90 degrees into the wind area so the tight tack is basically 45 degrees off the wind to either side. My boat is pretty comfortable with the bird flying on either guide depending on which side of the wind I am on. Theoretically that would seem to mean that I can tack 30 degrees off the wind instead of that theoretical 45. Yippee!! I'm a great sailor on a great boat. But wait. My boat doesn't have a working compass so I have to visually guestimate what angle my tack actually takes based on sig hting to the shore, or buoys or something. Depending on how fickle my lake wind is, it is pretty obvious that I am not able to sail as tightly as 60 degrees and sometime it seems it is a struggle keeping it at 90 degrees. So here is my question for the brain trust. Is this a function of apparent wind and I can do 60 degrees based on apparent wind but more like 90 degrees on actual wind? I had assumed that apparent wind related to how the sails moved the wind as it crossed over the boat. The twirly-do is above the sails and probably wouldn't be impacted by them so that would imply that apparent wind would be some sort of geometric interaction of boat direction (and speed) and actual wind direction. I'm having trouble getting my arms around that one. The other thing that is making me scratch my head is that (still without a compass) it appears that I can sail tighter into the wind with my 150 genoa than with the 120 that I use on heavier wind days. That goes against everything I have read before. Is this typical of C27 TR boats or is this an anomaly or do I just really need to replace my bad compass?? The other option is to just enjoy it and forget the logic of it all! Thoughts?? Jim Jim Bernstorf Jules Distribution 6025 Cloverland Drive Brentwood, TN 37027 615.833.1848
