[C320-list] 3-blade folding prop Size

[Steven Magennis]

According to Practical Sailor a few years ago, prop calculations
typically call for a larger diameter prop than will fit under our boats
(that is, unless you extend the shaft, put another strut / cutlass
bearing, etc).  To make up for not being able to fit the proper
diameter prop in the available space, the pitch is increased above the
optimum angle.

The Gori prop can have a larger diameter than the standard fixed prop
because the blades are located further aft than the blades of a fixed
prop, and there is more clearance the farther aft you place the prop. 
This is good, and allows the prop manufacturer to specify a prop that
is closer to the optimal pitch.  However, this pitch should be lower
than that of the fixed prop, not larger.

I would talk to other prop manufacturers (Flex-0-Fold and Martec in
particular) and see what they recommend for their version of the same
prop.  As I have reported earlier, I have the Gori 16.5 x 11 two blade
folding prop on my '02 C-320 with the Yanmar 3GM30 and (as I have been
told but have not confirmed), a 2.62: 1 transmission ratio.  All of
this info (Engine, transmission, reduction ratio, direction of
rotation, and shaft diameter) is required for the manufacturer to
correctly specify the prop.  Unless things have changed, you have a 1"
diameter prop shaft with right hand rotation.

Steve
Alchemist #909


--- belairlk at aim.com wrote:

> Allen,
>  
> Thanks---will research thoroughly---don't know why Gori and distrib
> recommend 16-1/2 x 12 when stock 3-blade is smaller.  Won't make
> decision to switch until and unless the correct size is determined.
>  
> Len
> Aqua5  #1070
>  
>  
> -----Original Message-----
> From: ATrowbridg at aol.com
> To: C320-List at catalina320.com
> Sent: Mon, 9 Jan 2006 18:20:41 EST
> Subject: Re: [C320-list] 2-blade or 3-blade folding prop
> 
> 
> Len, the max size you should go is 15 X 10 in a Gori 3 blade. Bigger
> will  
> put to much stress on engine. It should be the same as your stock
> prop. They  
> tried to put me in a bigger one and it didn't work.    Allen         
>     Kalen 
> #453
> !!- _______________________________________
> !!- C320-List at catalina320.com mailing list
> !!- Archives Here: http://www.catalina320.com/list/archives
> !!- Change Subscription Here: http://www.catalina320.com/list/change
> !!- Subscribe Here: http://www.catalina320.com/list/join
>
________________________________________________________________________
> Check Out the new free AIM(R) Mail -- 2 GB of storage and
> industry-leading spam and email virus protection.
> !!- _______________________________________
> !!- C320-List at catalina320.com mailing list
> !!- Archives Here: http://www.catalina320.com/list/archives
> !!- Change Subscription Here: http://www.catalina320.com/list/change
> !!- Subscribe Here: http://www.catalina320.com/list/join
> 



		
__________________________________________ 
Yahoo! DSL – Something to write home about. 
Just $16.99/mo. or less. 
dsl.yahoo.com