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West Wight Potter Mailing List maintainer
dfarrell@ridgecrest.ca.us
List hosted by www.tscnet.com
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I have been following this discussion with interest, but also
a lot of confusion.
I've got a 1987 Suzuki 4. I visited the Suzuki web site, and I
have obtained an owner's manual for this motor. However, I still
don't quite follow how to determine the ideal prop. I've only
used the motor a couple of times, and I seriously doubt it got
me anywhere near hull speed.
What I'd like to know is, what are some tests I can do without
the need to invest in knotmeters, radar guns, external RPM
indicators, and so on? Given the results, how do I interpret
them? How do I know if I need a larger or smaller prop?
Oh, one other question. You talk about the motors purring along
at 3/4 throttle. Ok. Tell me, how can I tell if the motor is
running smoothly and neither being pushed hard nor overrun?
I am completely deaf, so I can't tell by ear and I've yet to
figure out how to tell when the engine is in the groove. I can
tell if it's overrevved beyond a point by the sudden increase
in high vibrations. I can tell when it's running too hard by
the sudden balking, but there's a wide range in between those
two endpoints.
Bill B.
P-19 #454, "Dream Catcher"
Nampa, ID
Dave & Francesca Kautz wrote:
>
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> West Wight Potter Mailing List maintainer
> dfarrell@ridgecrest.ca.us
> List hosted by www.tscnet.com
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> Eric Henry wrote:
> >
> > - - - - - - - - - - - - - - - - - - - - - - - - - - -
> > West Wight Potter Mailing List maintainer
> > dfarrell@ridgecrest.ca.us
> > List hosted by www.tscnet.com
> > - - - - - - - - - - - - - - - - - - - - - - - - - - -
> > How would one determine the right prop required? I have a 99 merc 2.5 w/ factory plastic prop. Should I change it?
> >
> > Eric Henry
> > P-15
> > Trevorton, PA
> >
>
> The standard prop on the 2.5 hp Mercury, Mariner, Nissan, Tohatsu (all
> made by Marubeni in Japan) has a pitch of 144 millimeters which is 5.7
> inches. The optional propeller listed on the Nissan site has a pitch of
> 7 inches which would make matters worse. The Tohatsu owners manual
> mentions an optional propeller with a pitch of 110 mm (4.5 inches).
>
<SNIP>
> I think that if someone wanted to use the small Marubeni motor in either
> it's 2.5 or 3.5 hp configurations to drive the heavier P-19, the 4.5"
> prop might be a better choice. There's a fellow who has an Ensenada 20
> at the Marina where I often sail. He uses a 2 hp Johnson with a low
> pitch prop to drive that boat. You can always tell it's him. He moves at
> 3-4 kts. and the engine is screaming - It sounds like one of those model
> aircraft!
>
> Dave Kautz
> P-15 #1632, Tilly Lucy
> Palo Alto, CA
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