Gene Kearns wrote:
On Sat, 09 Jun 2007 14:48:33 -0400, trainfan1 penned the following
well considered thoughts to the readers of rec.boats:

Steve Barker wrote:
The reason for the step-down recommendation is because the aluminum flexes
Prove it.

Both do, but aluminum will bend up to about 4 times as much.....

Check the values for "modulus of elasticity:"

http://www.engineersedge.com/manufac...ous_metals.htm
http://www.engineersedge.com/manufac...ous_metals.htm

The chart you are referencing gives (-------), or -0- for shear modulus
of elasticity on cast aluminum alloys until brass is introduced. There
is some tension, of course(as in an application as fastening hardware).

Aluminum alloy props are very rigid & brittle as the chart shows.

Rob


and looses some pitch. Stainless does not.