Thursday, March 26, 2009

The waiting game

Way back in October Doug commented "However buying foils off the shelf is not very easy, so it is great that you are able to get them. I hope you get them more than a couple of weeks before the worlds as that seems to be standard...." Yeah, right, I thought at the time. Well, I'm here to admit maybe Doug was right. After over four months of waiting I'm now looking at a different vendor for my replacement foil. The only upside is that I really don't like cold water so wouldn't have been sailing these past four months. I did, however, hope to get back out in May. Now even that date looks suspect. I'll probably repair the old strut and make do with that set-up while awaiting (again) for delivery of a quality foil and strut.

Thinking about the tank data that Bill and John collected convinces me that excessive foil drag was slowing me down. I'm not a quality craftsman capable of producing slick foils like the production builders. My foils worked, just not as efficiently as they might have. So it's back to the waiting game.

On the aerodrag front, the tow data showed that areo drag of hull, racks, and helmsman is not insignificant. I'm wondering if the whole rig was measured, how much more the total drag would increase. My gut says that since the sails are generally designed as a low drag aerofoil, with lift producing characteristics (or possibly as a lifting aerofoil with low drag characteristics) the increase might be less than the measured parasitic drag of the stuff below the rig. I do remember seeing somwhere (Marchaj??) that a wire with a circular cross section (a typical stay) has the same drag as an airfoil section with ten times the max thickness. That is, a 1/8" shroud wire could have a foil section snapped over it up to 1.25" thick (and probably 3-4 inches long downstream) without an increase in drag. Maybe the unstayed mast approach really has significant benefits, especially at foiling speeds (resistance going up as the square of the velocity, right?) So skinny masts, finely aligned prodders, maybe plastic snap-on foil sections for shrouds and racks may all be a major line of development. The skinsuits I alluded to also cover the head, a necessity that some of us aren't concerned about...

Enjoy the waiting. I haven't.

The Waiting, by Tom Petty (1981)

Oh baby don't it feel like heaven right now
Don't it feel like somethin' from a dream
Yeah I've never known nothing quite like this
Dont it feel like tonight might never be again
We know better than to try and pretend
Baby no one could have ever told me 'bout this

The waiting is the hardest part
Every day you see one more card
You take it on faith, you take it to the heart
The waiting is the hardest part

Well yeah I might have chased a couple of women around
All it ever got me was down
Then there were those that made me feel good
But never as good as I feel right now
Baby you're the only one that's ever known how
To make me wanna live like I wanna live now

The waiting is the hardest part
Every day you see one more ca rd
You take it on faith, you take it to the heart
The waiting is the hardest part

Dont let it kill you baby, don't let it get to you
Dont let em kill you baby, don't let em get to you
I'll be your breathin' heart, I'll be your cryin fool
Don't let this go to far, don't let it get to you

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