[C320-list] Prop replacment

[Jon Vez]

Although I have an Autoprop, the characteristics are similar to your
flex-o-fold. They are heavier props and there is a lot of torque when the
blades are engaging and reversing, so a SS shaft will make a difference with
vibration--and extend the life of your cutless bearing. Your prop is
probably overpitched, which is why you can't get to full RPM's. The issue
with this is that if your engine isn't run at full RPM's occasionally, you
will have carbon buildup sooner, and perhaps the engine won't live quite as
long as it's useful life should allow. I've come to accept this and I just
check my exhaust system more frequently and if I lose a few hundred hours of
engine life, it's not a big deal since I should be able go well beyond 5000
hours with proper care and maintenance....

Regards,

Jon Vez
Solstice #582

-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Charles
Greenwell
Sent: Thursday, March 18, 2010 9:56 AM
To: c320-list at lists.catalina320.com
Subject: Re: [C320-list] Prop replacment

I have the 3 bladed flex-o-fold on my boat.  I have had it for 4 years
now sailing on the Chesapeake Bay.  I have the 3GM30, 1 inch shaft,  and
the 2.21:1 transmission. They supplied me with a 15x9 prop. The
improvement in performance under sail was amazing.  Prop walk in reverse
is virtually gone.  It takes a minute or so to stop the boat and start
going backwards. 

 

Now having said this, I have some issues with the prop that I have never
resolved.  First, vibration.  My prop tends to cause some vibration in
forward gear none in reverse. Its minor but annoying on long trips when
motoring.  Second,  in flat water no current, I cannot get the engine
RPMs above 3000.  These issues do not bother me very much since I rarely
motor the boat. 

 

My 320 was probably the first or second 320 that they supplied a prop
for.  I discussed these issues with them and they felt that the
vibration problem was most likely due to the prop being installed
improperly.  They may be right on this one.  The company that installed
the prop drilled a hole in the hub and put a set screw in it.  Not sure
why they did that (they said safety) but there was nothing I could do to
resolve the issue other than buying a new hub.  As for the RPM issue,
it has never been resolved.  The prop is very heavy and my mechanic
suggested that I change my prop shaft to stainless steel.  He felt that
the bronze shaft maybe flexing a little. I plan to do this but have not
gotten around to it yet.

 

Today there are many boats with flex-o-fold props, including the new
320's.  I am sure all of the bugs have been worked out. In fact, I
believe that most of the new 320 are supplied with a 16 inch prop
instead of a 15.

 

Don't forget to change your cutlass bearing when you put the new prop
on. Even if it shows no wear. 

 

Randy

Le Bijou

Hull 719