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From: R C Smith Jr (no email)
Date: Wed Oct 11 2006 - 09:31:35 EDT
On 10/11/06 8:26 AM, "Dave Cooper" <> wrote:
> There are two direct "costs" with operating active fins.
> One is the drag that they add to the boat both when locked and operating.
> Less of course when locked and more when operating and more even when they
> are operating full on.
> Two is the cost of the fuel to operate the pump that is driving them. Little
> when they are locked but quite a few HP when the pump is working full on in
> a bad seaway.
FWIW, in my experience with a 30 YO Naiad system, the pump is either on or
off. It does not seem to work harder if operating the fins or holding them
centered. But pressuring the system puts quite a drag on the engine, so I
never operate them unless I need them, leaving them to flop back and forth
in place. I am told that this could wear the shaft seals prematurely vs
leaving the fins centered. I could manually center them by inserting the pin
provided at the hull, but that is a pain. In 2700 hrs I have seen no leaking
or any operational problems...except adjusting for the chatter which
develops from time to time.
Regarding the drag from the fins themselves 24/7, I am blissfully unaware of
this cost...and I want to keep it that way!
Bob
________________
Robert Calhoun Smith Jr
M/V MARY KATHRYN
Hatteras 58 LRC
South River
Annapolis, MD
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