[C320-list] Prop Info

[Jeff Church]

Bob,

Thanks for the information.

You have more pitch than me and yet you are running at a higher rpm than I 
am. Do you know what your transmission ratio is? If yours is 2.62 that would 
explain the difference between your rpm and mine. I believe Catalina used a 
couple of different ratios.  I have the 2.21 transmission and with 18 
degrees of pitch I turn 3500 rpm at 7+ knots in flat calm conditions. Also, 
what is the maximum rpm you can get at full throttle?

My current pitch is OK for day-sailing, but I'm considering re-pitching to 
16 degrees so I can still get 3500 to 3600 rpm under less than ideal 
cruising conditions such as fully loaded boat, fouled bottom, headwinds and 
big seas. When I go on a long cruise those are the usual conditions when I 
would need to motor near full speed. As currently pitched, that kind of load 
pulls my max rpm down to around 3000 and the engine gets a bit stressed. 
MaxProp thinks I shouldn't need to re-pitch, Yanmar thinks I should.

Jeff


----- Original Message ----- 
From: "Bob & Bel Harrison" <b_harrison at shaw.ca>
To: "'C320-List'" <c320-list at catalina320.com>
Sent: Tuesday, November 07, 2006 11:51 AM
Subject: Re: [C320-list] Prop Info


Earlier this year we installed a 15" Three Blade Classic Max-prop to replace
a 15x9 3-blade fixed prop.
Engine is a Yanmar 3YM30, standard transmission.
The prop was set to the manufacturer-recommended 10.3 (20 degrees) pitch,
and here are some before & after boat speed measurements...

RPM   Fixed   Max-prop
2300    4.4    4.6
2600    4.85   5.13
2900    5.35   5.65
3200    5.8    5.95
3500    6.0    6.28

It seems to me that since the engine has no difficulty reaching high RPMs,
the prop could be pitched a little higher, say 11.4 (22 degrees).  I'm
considering changing it at next spring's haul-out, but on the other hand,
why mess with something that's quite satisfactory?

Bob Harrison
Maverick #1007


-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Jeff Church
Sent: November 6, 2006 11:06 AM
To: C320
Subject: [C320-list] Prop Info

The boats on the hard and I'm working thru my winter project list. I'm about
to re-pitch my MaxProp and I'd like to know what pitch other 320 owners are
using. MaxProp's database is out of date. They only list the C320 with a
Perkins diesel.

If you have a MaxProp and a Yanmar please let me know the pitch,
transmission ratio, and your maximum speed and RPM while motoring.

Aside from taking the results into account for my use, I'll update MaxProp
with the information.

Thanks

JeffC