[C320-list] Prop Info

[Jeff Church]

Bob,

I couldn't find the tach at auto shops, but I did find a good selection at a hobby shop that sells a lot of radio control airplanes and helicopters. They use them to measure propeller rpm. There a several RC web sites that also sell them.

Jeff
  ----- Original Message ----- 
  From: Bob & Bel Harrison 
  To: 'C320-List' 
  Sent: Thursday, November 09, 2006 12:16 PM
  Subject: Re: [C320-list] Prop Info


  Jeff,
  I just tried this, and got to maybe 4050 in neutral.  I was aware that it
  wasn't supposed to go that high, which was the reason we asked the mechanic
  to check the tach.  No hobby shop around here has heard of such a thing as
  an optical tach, and neither have the auto parts stores, at least under
  $400.  My bicycle computer does basically the same thing and a lot more for
  about $30, so I don't know why a handheld tach should be any different. EBay
  has one for $10 plus $40 shipping, so I'll try a few more places here
  (Vancouver, BC).

  Bob H.

  P.S.  After 3 summers, the boat has ~1050 engine hours, so we've probably
  used more oil for oil changes than Ken D. uses in diesel ;-).  We're at 90
  days on the water so far, but it looks like we won't quite make 100 this
  year, as the ski season starts in a couple of weeks!

  -----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 7:41 PM
  To: C320-List
  Subject: Re: [C320-list] Prop Info

  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