scott.projectsomewhere

It seems to be a bit like that lately.

I thought I’d worked it all out when I put some thought into how much flap movement I was getting and how that related to my downwind control. But it seems I was too smart by half.

The changes worked on my board, and it improved dramatically. So dramatic that Dave spent the next month in the workshop trying to figure out what I’d done and trying to better it.

Then it broke.

I found the same inital problems with Ben’s board in my boat, so on Saturday I made the same changes that I made to mine previously, but went one step further with the gearing. It didn’t work.

What I was finding was that the boat would fly along, relatively low in the water, then when it did go up, the wand would come forward, but stall in mid air about where the flap would be neutral. No amount of wand elastic would override it. On shore it was fine, the wand would move freely and easily through the full range from flap up to flap down.

What I had done was over gear the centreboard bellcrank, so it became almost a 1:1 relationship between the vertical and horizontal pushrod. The problem I think was that the flow over the flap became a stronger force than the flow (or lack of it) over the wand as it came free of the water.

So the boat would rise, the wand would come clear, and you’d get this floating sensation as it became unresponsive til either you pushed the boat down to get the wand tip back into the water, or you crashed.

I crashed a couple of times.

That’s my latest theory at least. There was no significant friction in the system, there wasn’t any significant play. Neither the bellcrank, or the pushrod, or the wand, or the ball socket was bottoming out, so I can’t think of any other explanation for why the wand would refuse to flick forward.

Next step is to restore the ratio in the centreboard, and then power up the wand gearing accordingly. That should get me back to where I started, in a round about sort of way.

Interestingly the wand didn’t have the same reaction that a Bladerider does, even though I was using all Bladerider parts. The BR wand movement appears to generate power as it comes forward, and I haven’t yet worked out how or why.

Anyway, I’ve got a while to work it out now, since there’s more important things to think about after the weekend.

This entry was posted on Monday, September 29th, 2008 at 10:56 am and is filed under Sailing. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.