[PUP] :PPM-propeller efficiency

[Patrick Gerety]

----- Original Message ----
From: John Marshall <johnamar1101 at gmail.com>
To:
Passagemaking Under Power List <passagemaking-under-power at lists.samurai.com>
Sent: Sunday, November 23, 2008 10:09:25 AM
Subject: Re: [PUP] :PPM-propeller
efficiency

>Do trawler manufacturers select the prop for perfect match at
full RPM?

In the early days at Willard Marine ('60's, '70's, '80's)  We
always over-propped the boats.  The theory was that if you could reach hull
speed at a lower RPM, you would save wear and tear on the engine.  But
conventional wisdom changed over the years as marine engines were made more
efficient.  Today, most marine engine manufacturers recommend a running gear
(engine, reduction gear, and prop) that will allow maximum rated RPM at WOT. 
Prior to cessation of production, Willard was propping their boats to achieve
max. RPM at WOT.

Patrick
Willard 40PH
ALOHA
La Paz, MX