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"The Plank Deflector"

September 9, 2004 - 06:15 — GeoffS

Ever since I got burned at the NAs last year by aligning my runners with an out of whack set of aligners, I've been thinking about how to align my chocks without relying on a "gold standard" fixture. Optically seems to be the only way to go to align things from "first principles".

Last spring I made myself a rifle-scope alignment tool along the lines of Bob Gray's suggestion on the DN Bulletin Board.

Now I had the tool to measure the relative alignment of my runners by sighting on a distant target. However, I wanted to align the runners with the plank deflected to the "light air" position. I also wanted to work at a comfortable height and position (no lying on the ground with the scope held up against the bottom of the runner for me). I wanted the runners facing up with the plank sitting on sawhorses. I remembered Ron Sherry talking about using a "dummy" 2x4 mast to load up his plank for tuning in the shop, and I thought that perhaps I could make a really short "mast" that could hang below the plank when it was resting upside down on sawhorses.

Last night I tried to mock something up in my shop. The 2x4 "mast" is a bit long (34") for most sawhorses, but it's what I had lying around the shop:
The The

No expense ws spared on the hardware. The turnbuckle is an Aluminum item I got at a local "Farm and Fleet" store, and the cable is some I got from an discarded E-Scow jib.

Nevertheless, I was able to easily deflect the plank 2 1/8" inches, well below flat:
The

Is this crazy? Am I missing something that would make this an inacurate method to align my chocks with the plank deflected?

Cheers,

Geoff Sobering
DN US-5156/Renegade 510
geoff_sobering@yahoo.com

Comments

October 6, 2004 - 21:26 — us5214

the dry wall squares worked good for me..

Hey geoff,

check out my blog about aligning my chocks.
http://iceboating.net/node/view/285

I used two _proven square_ dry wall squares. You clamp the ends to the chocks and then you can measure the alignment 4' out instead of just 2' or 2.5' feet with the regular method. I then epoxyed the chocks down. I was going pretty good last year and whenever I measured them with other tools they were square on.

happy it's getting cold,
jim

October 1, 2004 - 00:32 — unregistered skipper

Sounds similar to what we've

Sounds similar to what we've been doing except that we do it with a stiff bending fixture that the plank gets attached to instead of the 'mast'. (our shop has low ceilings and, we too, wanted to work on the plank at workbench height). We have since learned that a simplified lever approach works. (attach one end of it to one end of the plank and the fulcrum at CL and and pry it down to the other end and lock it in and measure to your hearts content. ...beats getting someone to sit still in the boat w/ a bag of salt in their lap. The only big concern is making sure that you are measuring it while it is deflected as close as possible to light air sailing state. There are several ways to ensure this. but careful measurement works best.
Erich

November 26, 2004 - 04:57 — Chris Gordon

How aboutr this:

For a primitive approach, I might try putting a bathroom scale on the plank, putting a car jack on the scale and a proper length 2"X4" to the ceiling and load it up like that.

It might work for me. I'll have to try it.

Chris Gordon