Joined: 21 Jul 2005
Location: Del Mar, California, USA
|Posted: Mon Jun 18, 2007 5:22 am Post subject: Windvanes and Kelp
|I have often tended to blissfully sail through some of our local kelp beds, thinking that I was fairly secure in view of our full keel, constellation rudder and prop in an aperture. It slowed me down, but could cut a few miles off the entry to our harbor in San Diego but cutting through the kelp bed - as long as I didn't turn on the engine! If I did that, then the prop and prop shaft became encased in a mass of kelp.
But there is another problem caused by kelp that has also finally been resolved. I occasionally noticied that our Fleming windvane didn't seem as responsive as usual. I generally attributed this to our light summer winds not providing enough of a signal to the airfoil. I had occasionally noticed that it snared kelp around the paddle in the water. But yesterday was a lulu. The wind was running a reasonably steady 6-8, usually more than adequate for the vane to steer the boat. But the pendulum simply wasn't moving much off the midline. It didn't swing even when I manually tilted the airfoil all the way to one side or the other. Looking down into the water, I again saw some kelp, but probably considerably more than on previous occasions.
I slowed the boat down enough so that I could get a boat hook around the kelp and managed to slide it up and then off the paddle. SHAZAM! The vane was once again working beautifully!
In retrospect, I simply had not appreciated how the laminar flow along the length of the kelp was generating so much energy that the windvane paddle was unable to respond to the changing angle of attack of the water flow across the blade.
Has anyone else had this problem?
Harvey J. Karten
Del Mar, CA 92014