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.