I mentioned a couple of posts back that I thought changing my vang strop lengths had improved my upwind speed. I finally got around to fixing up my GPS (soldering was required) so I could download the data from last week, and the polar diagram really tells the story.
You can clearly see that the effective tacking angle is much narrower (the red is before the change and the green is after). The average and maximum speeds, and VMG are all much higher. This is because I am now able to point high and foil instead of needing to low ride if I want to have any chance of actually making the windward mark.
The total adjustment was to shorten the top vang strop about 50mm. This really goes to show that the smallest thing, if incorrect, can make a huge difference. It also highlights the size of the hill you have to climb when you reinvent the wheel yourself.
November 16th, 2008 at 5:39 am
Bruce:
How did shortening the top strop improve the performance? Unless it resulted in being able to gain more throw or purchase in the vang, I’m at a loss to see how it could affect any difference in sail configuration.
Joe
November 16th, 2008 at 8:31 am
The adjustment allowed me to pull on a whole lot more vang.
I was block-to-block most of the time before. The sail looked OK, so I thought I was getting enough vang on, but based on the hard numbers it definitely wasn’t.