[C320-list] Boat Speed

Jamie Pett JPett at JP2ARCHITECTS.COM
Mon Jul 6 15:11:08 PDT 2009


Paul / Mark / Everyone - I posted an earlier thread (errantly without a
subject) regarding a tachometer anomaly, but also have the same question
regarding speed , rpms, etc.  - my boat has a 27 Yanmar.  

I understand it is normative to cruise at 3100-3200 rpm, but cannot get
the boat to go 6 kn. according to my gps at that rpm.  At 2800 I am
going 5 - 5.2.  Others seem to report 6- 6.2 on this list all the time ?
This is with reasonably clean bottom, full fuel, and about half tanks
for water - 25 ga. or so.  Aren't the Yanmar's recommended to cruise at
3000 plus ? 

Would love to see the spreadsheet.  

I also have a fixed 3 blade prop.  My good friend has a 320 with a
Perkins, and we 'drag raced' one day - his was clearly faster, with a 2
blade - no idea why - same keel, etc.   His boat may weigh a bit less -
mine has roller main, but I wouldn't think that some weight should do it
under power, and tankage wasn't that different at the time ? 

James Pett
Bella Luna
#614




-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Mark
Schiesser
Sent: Monday, July 06, 2009 5:54 PM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Boat Speed

Paul, 

I am glad to see your question as I have owned mine for 3 years and
experience the same thing.  My wife keeps telling me we need a bigger
engine.  I keep telling her "I knew you were a closet power boater"  
Your boat is a 27 hp or 18 Yanmar?
I have a prop that does not fold as such but twists to a neutral
position.
I noticed while inspecting just prior to going in the water this year,
it
has an adjustment to allow for attack angle adjustment.  It looks to be
adjusted significantly to one extreme.  I did not have an allen wrench
with
me that day to play with it some to see how the adjustment would affect
it.
I am also looking forward to the answers you get.

Mark

-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of pjaarch
Sent: Monday, July 06, 2009 5:39 PM
To: C320-List at Catalina320.com
Subject: [C320-list] Boat Speed


I just purchased my 320 several weeks ago and am concerned about the
boat
speed while under power.  I have a 3GM30F and cruise at about 5.4 knots
at
2700RPMs.  It seems slow to me.  I am currently cruising with other
boats, a
(hunter 28, beneteau 331, and an Irwin 38.)  They all cruise easily 6
knots
at 2700 RPMs and I can't keep up.  I have a 3 blade prop.  Could I be
under
proped?  What is the cruising RPMs for the boat?  I have no ID plate on
the
engine block.  I assume it is rated for 3400.

Paul Adison
C320 #722
"Rough Draft"






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