> They clearly just unscrew in situations like that.
Well, trolling motor props can't unscrew.
For those who don't have one, there is a shear pin through the shaft near the motor. The prop slides over the shaft, has a capturing slot for the shear pin, and is fastened in place by a locknut. The locknut has a pinch collar with a plastic insert at the far end.
If the nut has been reused a few times, the pinch collar no longer pinches enough to hold tight. If it is not tightened or becomes loose from vibration, the prop will unseat from the shear pin. Only, at that point, can the prop unscrew the nut.
Having stated that, I lost a prop just two days ago. Fortunately, we were testing props in a pool . . . which just happened to be the pool used in the 1996 Olympics.
The secret is to use a lock washer. If you don't use a flat washer, the lock washer will bite into the plastic making a very tight prop.
Two lessons to be learned. Don't trust the manufacturer to provide the right fastener. They want to sell more props. Don't venture out without a spare.
For those who are following my progress on Stream Dancer, the props we were testing were actually augers . . . that work equally well forward and reverse. Our other objective is to offer more pitch than the standard 4" pitch propellers from MinnKota & MotorGuide . . . to gain more speed.
We achieved the equal performance forward & reverse, but we haven't produced more speed. Unfortunately, the Ga Tech class partied too much and failed to dedicate enough time to the project during their
semester to get better results.
Meanwhile the contest for best boat design among high schools didn't accomplish much other than enthusiasm from students.
This project really needs an experienced boat builder to take over.
Happy Holidays,
John Zimmerlee
No comments:
Post a Comment