OK.
I'll check the length of mine and see.

I missed the second part of your question. I'd say you need to leave the arrow long. The extra length will help stabilize the arrow. The extra weight would help it penetrate the water and fish. And you're right, shortening it would just make it that much stiffer.

That's what I thought.

Until you presented the problem, I have never really thought about draw-weight vs. standard fishing arrow. However, I suspect that too much draw-weight might cause the long fiberglass shaft to overly "whip" I may be wrong, but something rings that bell. I have never used over 50# DW.

Also, you might consider tracing the problem to the reel you are using, There may be a drag factor being imposed upon the line.

Has anyone ever seen data enclosed with a fishing shaft that provides details concerning maximum draw-weight? I have not.

I really can't remember who told me that you shouldn't shoot straight fiberglass arrows out of todays high power bows. It may just be a bunch of crap? I went to Muzzy website and sent them an e-mail about spine ratings and weather or not they were safe with hard cams at 70lbs. I will let you know what they say.