http://www.yanmarhelp.com/i_propclr.htm

It makes sense all around. The need for an aperture is to allow smooth
flow of water into the prop, to reduce cavitation. Now that you have
all this smooth flowing water accelerated by the efficient prop, why
spoil it all by bumping into a rudder or other deadwood?

"Roger Derby" wrote in message
ink.net...
| Could it be for clearance when the rudder is deflected?
|
| Roger
|
| http://home.earthlink.net/~derbyrm
|
| "Brian Cleverly" wrote in message
| ...
| Does anyone have any thoughts/theories on the reason for extending
the
| prop aperture into the rudder when the rudder is hung off the back
of a
| long-keel.
|
| I would imagine it would drastically reduce rudder efficiency, but
| possibly allow more of the prop to receive undisturbed water when
| backing-up.
|
| Thots anyone ?
|
| Brian C
|
|