Hi Matt,

Matt Colie wrote:

Brian,

This might seem like a lot, but when you have to get a puller in there
to get the prop off the shaft, that may even be a little tight.


Not on this boat... The prop has been pulled, as has the shaft, and there was
more than ample room for the puller.


I also knew of two hull of the same class and one had the propellor
about centered in the aperture, the other had less than an inch forward
clearance. They had both had shafts replaced....


I think people have lost sight of the original question..

On this boat, the prop is placed in the aperture pretty much according to all
the expert's calcs as to what is a good situation.

My question was re the excessive continuation of the aperture into the rudder.

Then there is still the issue that the builder may just have choosen to
make the aperture large (it was written many places that this makes for
less rudder vibration under power - I don't agree). Builders (by
enlarged) make what is most effective for them to build and sell. Seldom
does competitive performance enter into the equation. This is why
service is available to re-fair keels and rudders.


A service I myself provide to others.

If you wanted to plug it to improve the rudder effectiveness, go ahead.
Just make the piece removable (and do your best not to leave hard edges
at the leading edge that will cause turbulance on the low pressure side).


Now that *is* a thought, but in this case it would only have to be large enough
to provide clearance for shaft removal.

I still go back to my original possibility that a large rudder aperture might be
there to provide better water flow to the prop when backing down. After all,
long keel boats are a bear to backup at the best of times.

But, again, a sailboat is primarily a sailboat, not a motor boat, and to my mind
rudder efficiency should take priority over prop performance.

Brian C

Matt Colie

Brian Cleverly wrote:

Matt Colie wrote:

Brian,

I was reminded in a design class that it was a resonable idea to
allow enough room to remove the prop without removing the rudder or
engine. Even on long keel boats, propellors sometimes take damage.

Matt Colie


I agree, but that wouldn't require the approx 6" additional clearance
this boat has.

Brian C

Brian Cleverly wrote:

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