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

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

Sometimes having the prop disintegrate is one of the
better options. I've got both a power boat and a sailboat, and my power
boat has a stainless steel prop on it. I really liked the idea
of having that tough prop on the boat until a friend of mine--a long
time boat dealer and mechanic--pointed out that when a stainless prop hits
the rock, the prop shaft is usually bent, and the lower unit seal destroyed
in addition to the prop being damaged. With aluminum props, its usually
just the prop.

The problem is somewhat more complicated for the sail boat, since the
prop is usually protected from grounding by the keel. This just leaves
relatively "soft" objects such as fishing lines to worry about. In the
event of hitting something hard such as a coral head with a prop, its
probably better to have the prop give instead of your shaft or transmission.

One more thing to think about.

Don W.



Glenn Ashmore wrote:

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.

On Wed, 29 Oct 2003 15:41:20 +0000, Charles Cox wrote:

A slight divergence from the original topic:

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.


Check out Kiwi props:

http://snoopy.falkor.gen.nz/kiwiprop/home.html

or Pirhana props

I'm sticking with what i know (metal props) even though they cost more.

Lloyd

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.


CDI might be the company. They have/had a line of props that looked VERY
sweet and were guaranteed to be more efficient, but they seem to have
stopped developing new ones. Just checked: they have a few on their
page: http://www.sailcdi.com/

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/