"Lloyd Sumpter" wrote in message
news
Hi,
After the "What prop should I use", I've done some research and thougth
I'd post what I've learned about various props.


Folding Prop:
This is the ultimate sailing-compromise prop. Under sail, the blades fold
down to become hardly more than a giant "teardrop" on the end of the
shaft, giving virtually no drag. Under power, the rotation pushes the
blades out, and the backward force pushes the blades out
completely. The downside of this is that in reverse, the force is
trying to FOLD the blades, and centrifugal force is all that's keeping
them out. This means VERY poor performance under power in reverse.

Examples...?
Cost: ??

I think Martec has their prices on their web site. I have a 27'er
and the 12 x 10 folding prop I need is about US$550. Gori was
in the same price range, if you're willing to bargain. Both these
companies make geared props, where there is an intermediate
gear between the blades that forces them to open at the same rate.
This keeps vibration to a minimum.

In general I agree that folders don't function as well in
reverse as a fixed, but if you just increase engine RPMs
you can get the thrust you need for most situations.