E23 whisker pole

Does anyone have any advice for fabricating a whisker pole? I have the materials, 2" and 1 7/8" (telescoping) aluminum tubing and forespar ends. Is there a way to figure how long to make it? I plan on using a pin to adjust the length for 120%, 135%, 150% and an asymmetrical spinnaker. My boat is an E 23 mk1.
Thanks, Mark

Whisker stuff

I'm pretty sure the rules do not allow you to extend your pole beyond 1.4 X J measurement, and you would want the pole as extended as much as you can most of the time. Also, the ideal length for a given sail may vary with the wind angle you are sailing. When dead downwind you likely want full extension, but something less when reaching with the pole forward. So, you may be making things a bit more complicated than they need to be. However, if you are curious, the approximate foot lengths for your sails are:
120%:13.1, 135%:14.7, and 150%:16.45. You are limited to a max entension of 14.22, though.
Bottom line, maybe have a mark about 1 foot short of fully extended for smaller sails, then simply go max for 135% and bigger-make sense?

Have fun, and good times!

Seth