Laser Cheat Sheet. Watching windsurfers has always fascinated me. I love the way they pull the rig to windward as shown on the left. They dig in when a gust hits and then take off. If the gust is really strong, it knocks them vertical but they're still under control.
Less experienced windsurfers sail with the rig straight up, as shown in the middle. When a gust hits, they're knocked over, out of control, and overpowered even through they're spilling wind.
Heeling to windward, trapping the wind, and going vertical in a gust all seemed to make sense, so of course I wanted to try it in a Laser. And this led me to another discovery from sailing at night. Here's what I learned:
· This only works in relatively flat water.
· You cannot go block-to-block and the boom appears to be higher in the air because of the windward heel.
· The feeling of speed only lasts for a few seconds and you then have to go vertical and bear off a little to keep your speed.
· But the best part: you can really feel the lift from your centerboard as it digs in.
Volumes have been written about getting more lift from sails, but how much has been written about getting more lift from your centerboard? Water is more than 800 times denser than air, so how the centerboard moves through water really should matter. Just hold a centerboard beside a motorboat moving even slowly and try different angles and you'll feel the lift.
Here's what I think is happening. The windsurfer in the middle diagram has the wind go across the sail, which is what we expect. The windsurfer on the right has the air go up the sail. Both are bad because of the vortex created at the top of the sail. Airplanes have this same problem with the vortex at the end of each wing, and they're refitted with winglets to reduce these vortexes and save about 5% in fuel costs.
|Courtesy of Boeing|
The windsurfer on the left heeling to windward has the wind going down the sail and there is no vortex because the water is acting like a winglet. The air is trapped and not wasted. It's similar on a Laser when heeled to windward with the air trapped at the bottom of the sail, and it's fast. But that's not the best part!
Everything is the same below the water with the centerboard, except it's reversed: the push comes from the leeward side, the lift is on the windward side, the water flows up, and the winglet is the hull. And you can feel the centerboard dig in and lift, and this force can be significant as our motorboat test showed.
When we were in
visiting Frank Bethwaite, I asked if he agreed that this hull-as-a-winglet was probably the reason for the lifting feeling and he agreed. So, we still have much to learn about how to get extra speed when sailing Lasers. Sydney
And with the right touch, this trick is easy to learn. When Pam was brand new to Lasers, she lifted so much that I had to keep asking her to please put her foot in the water so that I could catch up!
|Excellent form... and fast!|