[C320-list] Tach reads only 3000 rpm at full throttle

[Chris Burti]

Barnacles on the prop will do that fairly suddenly.

On 8/28/07, Jim and Stacey <bredar-sewell at comcast.net> wrote:
> I have a 3GM in my 2003 C320, Hull no. 937.   I have 300 hours on the
> engine.   Full throttle has always yielded a tach reading of just over 3600.
> Yesterday I noticed that with the throttle full forward, the tach reads only
> 3000 rpm.     What gives?   I don't have a keen enough ear to say whether
> the engine sounds like it is actually at 3600 even though the tach says
> 3000.    Thoughts and suggestions appreciated.
>
> Jim Bredar, "Ranger", C320 No. 937, Oxford, Maryland
>
>
>
> -----Original Message-----
> From: c320-list-bounces at catalina320.com
> [mailto:c320-list-bounces at catalina320.com] On Behalf Of brucestanley
> Sent: Tuesday, August 28, 2007 5:42 PM
> To: C320-List
> Subject: Re: [C320-list] calibration of my Tach
>
> Thanks Jeff
> your explanation is appreciated.
>
> BruceStanley
>
> ----- Original Message -----
> From: "Jeffrey Hare" <Catalina at thehares.com>
> To: "'C320-List'" <c320-list at catalina320.com>
> Sent: Wednesday, August 29, 2007 12:24 AM
> Subject: Re: [C320-list] calibration of my Tach
>
>
> > The Yanmar 3GM series engines use a pickup on the flywheel to handle the
> > Tach instead of the terminal on the alternator, so those with the 3GM
> > engine
> > don't usually have any re-calibration necessary when changing alternators.
> > Given that you probably have the 3YM engine, it appears that they aren't
> > using the flywheel pickup anymore in favor of the Tachometer terminal on
> > the
> > back of the Alternator like they do for the other non-yanmar engines on
> > the
> > C320.
> >
> > -Jeff
> >
> > -----Original Message-----
> > From: c320-list-bounces at catalina320.com
> > [mailto:c320-list-bounces at catalina320.com] On Behalf Of brucestanley
> > Sent: Tuesday, August 28, 2007 3:14 AM
> > To: C320-List; oldman1030 at hotmail.com; sthompson at toad.net
> > Subject: [C320-list] calibration of my Tach
> >
> > Hi All
> > re: the calibration of my Tach after I switched from the Hitachi 60Amp
> > to an older Hitachi 80Amp. The 80amp Alt produced far higher Tach
> > readings.
> > This I solved by a terminal wiring alteration to the back of the Tach.
> > This terminal was straight forward. I did this approx 14 mths ago.
> > I am far from an electronics expert, but that is exactly what I did.
> > I am a DIY advocate and love doing most of my own work on my Yacht.
> > Parts I do not understand and parts I break. I still enjoy the journey.
> >
> > BruceStanley C320#1084
> > Sydney Australia
> >
> > ----- Original Message -----
> > From: "Chris Holt" <oldman1030 at hotmail.com>
> > To: "C320-List" <c320-list at catalina320.com>
> > Sent: Monday, August 27, 2007 9:48 PM
> > Subject: Re: [C320-list] Club Racing the C320
> >
> >
> >> That was what I had thought also.  I also did not experience any
> >> perceived
> >
> >> change of my tach readings after the installation.  I have a 1997 with a
> >> 3GM motor.
> >>
> >> Bruce,  maybe you experienced this because of a different setup on the
> >> 3YM
> >
> >> engines.
> >>
> >> Chris
> >>
> >> ----- Original Message -----
> >> From: "Scott Thompson" <sthompson at toad.net>
> >> To: "C320-List" <c320-list at catalina320.com>
> >> Sent: Sunday, August 26, 2007 7:09 PM
> >> Subject: Re: [C320-list] Club Racing the C320
> >>
> >>>I don't know about the newer or older boats, but on my 1999 boat there is
> >>>no need to recalibrate the tach when switching alternators.  That's
> >>>because on the Yanmar 3GM series of engines, the tachometer reading comes
> >>>from a sensor in the flywheel housing that counts the flywheel teeth as
> >>>they rotate past.  In these engines tachometer calibration has nothing to
> >>>do with the alternator.
> >>>
> >>> Scott
> >>>
> >>> brucestanley wrote:
> >>>> Hi Stephen
> >>>>
> >>>> re Kiwi Prop and Engine Revs
> >>>>
> >>>> Fantastic Lady's 3YM30 cruises at 2100 to 2900 rpm.
> >>>> Depending on tide/wind, this delivers 4+++ to 6+ knotts.
> >>>> Occasionally I advance the Revs to 3000 and 3300rpm.
> >>>> Sometimes to 3500++RPM for only a few minutes.
> >>>> Revs are a bit of a lottery, in that one hopes the Catalina Tach is
> >>>> calibrated accurately.
> >>>> I am reasonably sure they are close to correct on Fantastic Lady.
> >>>> Note: if you change your alternator you have to make a change at the
> >>>> Tachometer.
> >>>> I have an 80amp Hitach Alternator and have made this change.
> >>>>
> >>>> You must be able to Rev to 3600RPM (Yanmar's requirements).
> >>>>
> >>>> Hope this helps
> >>>>
> >>>> Bruce Stanley
> >>>> C320  #1084 Fantastic Lady / Sydney Australia
> >>>>
> >>>> ----- Original Message ----- From: "Stephen Cox" <scox at timmin.com>
> >>>> To: "'brucestanley'" <brucestanley at optusnet.com.au>
> >>>> Sent: Thursday, August 23, 2007 1:30 PM
> >>>> Subject: RE: [C320-list] Club Racing the C320
> >>>>
> >>>>
> >>>>> Thanks Bruce.
> >>>>>
> >>>>> What revs can you get your motor up to with this prop?
> >>>>>
> >>>>> Stephen Cox
> >>>>> Canberra
> >>>>>
> >>>>>> -----Original Message-----
> >>>>>> From: c320-list-bounces at catalina320.com
> >>>>>> [mailto:c320-list-bounces at catalina320.com] On Behalf Of brucestanley
> >>>>>> Sent: Thursday, 23 August 2007 8:20 AM
> >>>>>> To: C320-List
> >>>>>> Subject: Re: [C320-list] Club Racing the C320
> >>>>>>
> >>>>>> Stephen
> >>>>>>
> >>>>>> My Kiwi prop is 16.5"
> >>>>>> and The factory has set the angle at 22 degrees.
> >>>>>> This pitch setting of 22degrees is based on the engine you have.
> >>>>>> Mine is the Yanmar 3YM30.
> >>>>>>
> >>>>>> Bruce Stanley
> >>>>>> C320  #1084 Fantastic Lady / Sydney Australia
> >>>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>
> >>>
> >>
> >>
> >
> >
> >
> >
> >
>
>
>
>


-- 
Chris Burti
Farmville, NC