[C320-list] Prop Info

[Jeff Church]

Bob,

I can't even get to 3900 in neutral, but the maximum no-load rpm spec is 3850 so maybe your tach is off. If you want to check it, you can buy a optical tach at a hobby shop for $25.

I spoke with a different MaxProp tech today and got a different answer regarding the correct pitch. This guy says 16 degrees would be a good setting for cruising conditions. I knew if I called enough I'd eventually get the answer I was waiting for. 

I'm surprised that there aren't more MaxProp owners on this mail list! 

Jeff
  ----- Original Message ----- 
  From: Bob & Bel Harrison 
  To: 'C320-List' 
  Sent: Tuesday, November 07, 2006 9:01 PM
  Subject: Re: [C320-list] Prop Info


  My transmission ratio is 2.62.
  We can reach 3900 RPM, but it starts to heat up very quickly over 3300, so
  we usually motor for long stretches around 2800.  Only if necessary, of
  course.  Once in a while we run at high RPM for 5 minutes or so, as Yanmar
  recommends.
  It sounds like we both should re-pitch - - yours lower and mine higher.

  Bob H.


  -----Original Message-----
  From: c320-list-bounces at catalina320.com
  [mailto:c320-list-bounces at catalina320.com] On Behalf Of Jeff Church
  Sent: Tuesday, November 07, 2006 2:46 PM
  To: C320-List
  Subject: Re: [C320-list] Prop Info

  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