One advantage of using the manufacturer's recommendation though, is that if it
isn't quite right, they will usually fix it. My three bladed Gori would not
quite get up to max RPM, and smoked a little bit, so I sent it back. They sent
it over to Denmark or wherever they make them and took a half an inch off the
OD, airmailed it back, and it worked perfectly
Bill ColemanC&C 39
-------- Original message --------
From: "Dennis C. via CnC-List" <cnc-list@cnc-list.com>
Date: 12/18/17 11:24 (GMT-05:00)
To: CnClist <cnc-list@cnc-list.com>
Cc: "Dennis C." <capt...@gmail.com>
Subject: Re: Stus-List PROPELLER PITCH
Take prop manufacturers recommendations with a grain of salt. Years ago I
requested a recommendation from Flexofold. The rep at the time was Chuck Angle
who was highly regarded. He said he didn't have a good prop recommendation for
my 35-1. :) I went with Martec.
In 2011, I repeated the request and got a recommendation for a 15 x 12.In 2016,
I again asked and they said 16 x 12.
Currently, Touche' is swinging a 14 x 14 Martec which seems a bit under pitched
(or too small a diameter). I can run at 6.4-6.5 knots at cruise rpm (80% max,
2450 rpm) and flat water, no wind.
On my list for next year's haul out is to measure and document (photograph) the
prop tip clearance distance. I will also measure the hub and swing pin
location. The swing plane for different props varies.
I think prop selection is part science, part art and a bit of voodoo.
Dennis C.Touche' 35-1 #83Mandeville, LA
On Mon, Dec 18, 2017 at 9:59 AM, Rick Brass via CnC-List
<cnc-list@cnc-list.com> wrote:
The problem that I see with this calculator is that there is no value for prop
diameter (and slip is pretty intangible, though I suspect using .10 slip might
be a good approximation for 90% efficiency). The rule of thumb that a local
propshop told me is that changing prop diameter by 1” is approximately
equivalent to changing the prop pitch by 2”. So diameter also enters into the
calculation. I believe each prop maker has their own calculator for
recommending initial diameter and pitch, based on boat weight, engine HP and
targeted cruising RPM, transmission reduction ratio, and hull speed. Rick
BrassWashington, NC From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On
Behalf Of svpegasus38 via CnC-List
Sent: Sunday, December 17, 2017 5:56 PM
To: cnc-list@cnc-list.com
Cc: svpegasus38 <svpegasu...@gmail.com>
Subject: Re: Stus-List PROPELLER PITCH Try this propellor calculator.
rbbi.com/folders/prop/propcalc.htm Sent from my T-Mobile 4G LTE DeviceDoug
Mountjoy POYC Rebecca Leah Lf39 -------- Original message --------From: Bunky
via CnC-List <cnc-list@cnc-list.com> Date: 12/17/17 14:18 (GMT-08:00) To:
cnc-list@cnc-list.com Cc: Bunky <richard.h.bernst...@uvm.edu> Subject:
Stus-List PROPELLER PITCH Luna is a 1984 C&C 35 with a Yanmar 3gm30 engine.
Does anyone know what
the proper propeller pitch should be? She has an aftermarket Maxiprop,
and based on engine performance, I believe the pitch may be set too high.
Richard
Luna, Lake Champlain, VT
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_______________________________________________
Thanks everyone for supporting this list with your contributions. Each and
every one is greatly appreciated. If you want to support the list - use PayPal
to send contribution -- https://www.paypal.me/stumurray
_______________________________________________
Thanks everyone for supporting this list with your contributions. Each and
every one is greatly appreciated. If you want to support the list - use PayPal
to send contribution -- https://www.paypal.me/stumurray
