[C320-list] Ideal Engine RPM

[Quentin Murphy]

Hi All:

There has been a lot on the ideal RPM to run the engine at.  I don't have
this "chart" many of you are referring to.  I get the impression that the
best cruising speed is either 2800 or 3200.  Some suggest above or below
this range.  First of all, the recommended RPM in the "chart": are these
values based on our model of boat?  Is there a chart for our boat with the
Yanmar engine that show (a) RPM, (b) hull speed, (c) water surface
conditions, and (d) relative fuel consumption?  For this purpose, hull speed
would only be that over water.  Such a chart would be handy to those of us
who have put few hours on the engine at this stage.

Quentin Murphy
Celtic Knot #667

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com]On Behalf Of Bruce Heyman
Sent: Thursday, September 14, 2006 1:22 PM
To: 'C320-List'
Subject: Re: [C320-list] Regatta Tech Sessions - a summary.


Bryan,
What chart are you using?  The only one applicable that I see is on page 1-7
of the Service manual.  It shows the fuel is most economical at about 2800
RPM but does not significantly increase up to 3600.  Unfortunately I don't
think this is directly applicable as it is a factory floor test and not in a
boat driving a prop.

Our experience was that we ran for about 8.5 hours down to the rendezvous
last week at 2800 rpm, speed was great, often 6.9-7.1, but we drank close to
half a tank. On the way back we cut it back to 2500 and it seemed to use
significantly less fuel.  Not very scientific though as my guess is the fuel
gage is not well calibrated.

Bruce
Somerset 671 SoCal

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Bryan Campbell
Sent: Wednesday, September 13, 2006 6:01 AM
To: C320-List
Subject: Re: [C320-list] Regatta Tech Sessions - a summary.

I agree with Jon. Also note that the specs chart shows fuel consumption of
.52 gal/hr at 2400rpm. With a clean hull, no current, or head wind,  I get 5
knots at 2400rpm. 2800rpm bumps close to 6 knots.

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com]On Behalf Of
jonvez at comcast.net
Sent: Wednesday, September 13, 2006 6:19 AM
To: C320-List
Subject: Re: [C320-list] Regatta Tech Sessions - a summary.


Scott,

I also have a '99 and have the same information. I guess my concern is
running at 3400 is still not realistic for me. Even 2800 doesn't increase
the speed---I tend to run between 2100-2400 RPM--this is where I seem to get
max. speed and engine doesn't feel like it's going to jump out of the boat.
--I think the comments around 3600 being the max 1 hour run time make sense
as does the suggestion to check the tach (although I think mine is fairly
accurate)

Regards,

Jon Vez

-------------- Original message --------------
From: "T. Scott Thompson" <sthompson at toad.net>

> The owner's manual for my 1999 Yanmar 3GM30F pretty clearly states that
> the engine is rated at 3400 RPM for continuous operation and 3600 RPM
> for the one hour rating. My understanding is that this means that the
> recommended cruising RPMs are 3400.
>
>
> bruceheyman at cox.net wrote:
> > Jon,
> > Would be interested what others can get the autoprop up to. When I tried
it
> yesterday iit only made it up to 3300 or so. I'd also be interesting what
> everyone considers the proper crusing RPM. At the regatta I heard
everything
> from 3000 to 2100. I always heard that desiels do best at 80% of red line.
> I've looked theough the owners manual and the shop manual for the 3GM30F
and
> they offer no insight.
> > Thanks,
> > Bruce
> > Somerset 671 SoCal
> > Sent via BlackBerry from Cingular Wireless
> >
> > -----Original Message-----
> > From: jonvez at comcast.net
> > Date: Tue, 12 Sep 2006 17:37:42
> > To:catalina at thehares.com, C320-List
> > Subject: Re: [C320-list] Regatta Tech Sessions - a summary.
> >
> > Jeff,
> >
> > Thanks for the recap, very good info. all around....A couple of items
from the
> Yanmar discussion certainly stand out--certainly the comment on the
Dexcool and
> also getting the engine up to 3600 regardless of the prop...not sure I can
do
> that with my Autoprop....
> >
> > Thanks again for keeping those of us who could not make it informed...
> >
> > Regards,
> >
> > Jon
> >
> > -------------- Original message --------------
> > From: "Jeffrey Hare"
> >
> >
> >> Hi All,
> >>
> >> At this year's regatta, Dick organized tech sessions by:
> >>
> >> * Mark Felgenhauer at Garhauer Marine,
> >> * A technical guy from Lewmar,
> >> * A Yanmar technical representative
> >> * Some riggers demonstrating how to tension and adjust the mast rigging
on a
> >> C320.
> >>
> >> This is about all I remember from those sessions. If you attended and
have
> >> things to add or corrections to make, please feel free to note them and
make
> >> corrections. I'd like to post as much information from the tech
sessions as
> >> possible on the website, but since I didn't take any written notes, I
> >> probably forgot about lots of things that were discussed. I may also
have
> >> made some mistakes below in trying to write this email, so "have at
it!".
> >>
> >>
> >> GARHAUER:
> >> =========
> >> The session with Garhauer was an interesting opportunity to see the new
> >> products they've introduces for the C320, and ask tech questions about
> >> applications. One of the most interesting new products is the
replacement
> >> Genoa turning block for the one in the cockpit near the primary
winches. It
> >> is a beautifully manufactured block that's a perfect replacement for
the
> >> stock Lewmar one. The main difference is that the Garhauer block has
> >> bearings and handles the sheet loads way better. It's beautifully
> >> anodized and machined from an aluminum block.
> >>
> >>
> >> LEWMAR:
> >> =========
> >> The Lewmar rep, discussed how to disassemble the side hatches, stop
leaks
> >> and adjust the latch mechanisms. He discussed the 4 types of side
hatches
> >> used on the C320, and showed the new Stainless Steel framed replacement
> >> hatch used on the current and future C320s. He also indicated that
Lewmar
> >> now makes all the hatches on the C320, so at some point the forward
hatch
> >> went from being a Bomar, to a Lewmar. It would be interesting to know
when
> >> this change occurred.
> >>
> >> My observations: (from memory)
> >> There are two shapes for the standard side hatches. Rectangular Ends &
> >> Rounded Ends.
> >>
> >> As a common note, he indicated that replacement inside rubber seals on
the
> >> side hatches are available and replaceable if they're damaged and leak,
but
> >> keeping them clean and having the closing tension properly adjusted
(where
> >> possible) should eliminate leaking through this seal.
> >>
> >> Rectangular End side hatches:
> >> ==========================
> >> Used on the Earlier C320's (prior to ~2000??), and have the twist style
> >> of hatch closure.
> >>
> >> There are two styles of outside frame for these. The older style has a
> >> horizontal seam in the center of each end, and those that have a single
> >> vertical seam at the bottom. The older styles were prone to the sealant
in
> >> the seams drying out and allowing water to enter the hatch frame, and
leak
> >> inside. He had a procedure that would help eliminate or reduce that
> >> leakage. The newer version of the rectangular hatch had a vertical seam
on
> >> the bottom and was far less prone to leaking. But he said, to pull the
> >> inner trim ring and if you see water in there after a rain, then the
rubber
> >> in the outer seal is probably leaking. Someone who took notes, may have
> >> more details here.
> >>
> >> He indicated that there were a couple versions of the twist lock
> >> closures on the rectangular frames. Ones that had the catches welded,
and
> >> others that had the catches screwed in. He had a procedure that would
let
> >> you adjust the closing tension here.
> >>
> >> Rounded End side hatches:
> >> =======================
> >> Used on the newer (post ~2000-ish?) C320s and have the flip up/down
> >> hatch closures.
> >>
> >> Lewmar has made a few different versions of these side hatches, with
the
> >> differences being mostly in the appearance of the finish on the
aluminum
> >> outside trim.
> >>
> >> The newest version has a SS outside trim ring and looks very nice. The
> >> rounded end hatches can be directly replaced with the current polished
> >> Stainless Steel side hatches since the sizes and hull opening
requirements
> >> are identical. They are not a direct replacement for the squared end
side
> >> hatches however. I forgot to ask about whether they have better side
> >> screens on the new SS hatches.
> >>
> >>
> >>
> >> YANMAR:
> >> =========
> >> He mentioned quite a few things. Some of them I remember, most of
> >> them I don't. :)
> >>
> >> * Again, he reiterated that regardless of which prop you have, the
> >> engine needs to be able to reach 3600 RPM under load or the prop is
> >> overpitched.
> >>
> >> * He indicated that a 2 micron filter was a good idea and that the
> >> engine and pump has absolutely no difficulty with this fine a filter. I
> >> mentioned (after his presentation was over) the discussions this list
has
> >> had and the concerns some raised about not getting a good enough flow
with
> >> 2u filters. He said that the engine is efficient and doesn't need to
move
> >> lots of fuel, so fuel starvation isn't going to happen just because you
use
> >> a 2u filter. He indicated that the difference in fuel flow through 2
and
> >> 10 micron filters is really quite minimal. He indicated that the finer
> >> filter is better for the injectors and that 2micron is stock for newer
> >> yanmars anyway. Filter size does matter in really cold (below freezing)
> >> weather where diesel gelling issues are possible. But I'm tucked in at
home
> >> beside the fireplace in those conditions anyway. :)
> >>
> >> * He discussed the differences in the 3YM vs. 3GM. Mainly that the
> >> seawater impeller is easier to change.
> >>
> >> * He indicated that we should CHANGE our ANTIFREEZE to the DexCool
> >> variety. He said yanmar found that the Green (and others?) were
possibly
> >> the cause of corrosion in the aluminum parts of the heat exchanger.
Yanmar
> >> is using DexCool in these engines exclusively now. (Please correct me
if I
> >> missed something here). We discussed flushing it out, and he said that
we
> >> should try to get as much out as possible, but not to worry about small
> >> amounts left in there, that small amounts mixing wouldn't be harmful.
> >>
> >> * He mentioned that the impeller should be checked every year, and
> >> replaced every ?2?. (I forgot his exact answer, but he indicated that
look
> >> for wear and cracking.)
> >>
> >> * He cleared up the "impeller mystery" between the European and
> >> Japanese Yanmars. He said that there are 2 different pump
manufacturers.
> >> Johnson, and Yanmar. The Yanmar pump, needs an impeller with the keyway
and
> >> a paper gasket. The Johnson pump uses a rubber O-Ring and has a slotted
> >> shaft that accepts an impeller with a screw through the center of the
hole
> >> in the impeller. He indicated that the Japanese Yanmars typically (but
not
> >> always) used the Yanmar pump, while the European Yanmars typically used
the
> >> Johnson pump.
> >>
> >> If you have an engine with the JOHNSON PUMP (it says so right on the
back
> >> plate), you can use the Johnson impeller kit which comes with the
oring,
> >> some unneeded paper washers and the impeller. Yanmar also sells this
> >> impeller, but sells the o-ring separately (and is probably more $$). He
> >> recommends just getting the Johnson kit if you have the johnson pump.
> >>
> >> If you have an engine with the YANMAR PUMP, (may say yanmar, but
doesn't say
> >> Johnson :), then you probably have to buy the impeller through Yanmar
or
> >> some other OEM supplier. It needs the paper washer.
> >>
> >>
> >> RIGGING:
> >> ========
> >> The riggers discussed how to tune the rig. They indicated that the cap
> >> shrouds should be tensioned to no more than 12% breaking strength.
> >>
> >> They demonstrated proper use of the Pro version of the Loos gauge.
> >>
> >> They recommend the use of Boshield T9 spray on the turnbuckles to
penetrate,
> >> lube and seal out moisture. DON'T use this on turning blocks however
> >> because it leaves a waxy buildup behind. Sailkote or other dry lubes
are
> >> preferred for turning/sliding blocks.
> >>
> >> They spent a considerable amount of time discussing the concept of
pre-bend
> >> in the mast. (my interpretation and words follow here, so correct me if
I
> >> incorrectly conveyed what they said)
> >>
> >> Pre-bend is a slight bend in the mast arching aft. Even for a furling
main!
> >> The reason is that when the mast is perfectly straight in column, the
middle
> >> will tend to pump (wiggle fore and aft) which will cause damaging
fatigue
> >> stresses on the mast.
> >>
> >> They indicated that we absolutely want to ensure that our mast has some
> >> pre-bend. This is accomplished by ensuring that the FORWARD LOWERS are
> >> tensioned properly and tighter than the AFT LOWERS, and that the
backstay is
> >> not too loose. This is to pull the middle section of the mast slightly
> >> forward and introduce some bend.
> >>
> >> An interesting side-note: While at the Marina Del Ray regatta a couple
> >> years back, I noticed that most of the C320s there had very loose
(almost
> >> floppy) forward lower stays.
> >>
> >> An observation on their techniques: If you've seen Brion Toss's video
on
> >> rig tuning, he has a far superior technique for adjusting the
turn-buckles
> >> which puts less stress on the turnbuckle and is easier.
> >>
> >> Procedurally, they said, put enough tension on the cap stays (highest
one)
> >> to keep the mast from falling down. Then generally work from the bottom
up,
> >> side to side until the shrouds are up to tension.
> >>
> >> There was a lot more, but it seemed obvious to me, so I don't recall
> >> specifically what they said. Sorry!
> >>
> >>
> >> -Jeff Hare
> >>
> >>
> >>
>
>
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