I have seen some on outboards and high powered inboard ski boats but not
on cruisers. Piranha makes a replaceable blade composite outboard prop
that they claim is stronger than aluminum and I understand that
composite props up to 9' diameter are being produced in the UK.

The thing is, when they hit something the blades don't get bent. They
totally disintegrate.

Charles Cox wrote:
A slight divergence from the original topic:

Our company is starting to work with urethane resins to produce custom
enclosures for our electronics products. In the documentation from the resin
manufacturer, they show a propeller being cast from one of their specialty
resins. I've never heard of a plastic prop of any substantial size, but the
characteristics of some of the higher-end resins seem quite advantageous for
such an application. Nearly as strong as metal, but no corrosion and much
lighter. Presumably quite inexpensive to manufacture, even for one-off
applications.

I'm wondering if this is something that might become more commonplace as resin
technology advances, or if there is some reason why metal is superior. At the
very least, it could be a cheap way to make an inexpensive emergency replacement
prop. We have no interest in developing props ourselves, I'm just curious.

--
Chuck Cox
SynchroSystems Motorsport Computers
Hopped/Up Racing Team

http://www.synchro.com

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com