Re: [Amel Yacht Owners] Speed vs. RPM

Krassopoulos Dimitris <dkra@...>

I agree that the Autoprop is sensitive to marine growth but any propeller is
I think. Regarding SEAJet product I tried it without any good result. So I
do not recommend it.

My question to John : what was the speed difference with the autoprop and
the fixed propeller?

SM 2000 Alma Libre


-----Original Message-----
[] On Behalf Of John McDougall
Sent: Monday, March 13, 2006 2:12 PM
Subject: Re: [Amel Yacht Owners] Speed vs. RPM

Hi Claude & others
My SM2000 no 330 had the Yanmar/Autoprop combination and max revs
would frequently drop to about 1700. This was always cured by
cleaning the prop. My berth is in Antibes and the rate of marine
growth seems very high there for a reason we needn't go into but
let's say the harbour fish are large and fat. Quite expensive as I
don't dive (and certainly wouldn't in the marina!). The prop was
subject to a recall by Bruntons and in May 2004 I had Amel fit the
spare fixed blade prop. This prop is still fitted.

It is difficult to compare the performance of the fixed prop against
the Autoprop but I would say the difference is so slight as to be
unoticeable without making a test under identical conditions. I
agree that the Autoprop is extremely sensitive to fouling and I have
specified a fixed blade prop on my "54" to be delivered at the end
of this month.

Finally, before the fixed prop was fitted I had it treated with
PROPSPEED a silcone based propellor antifouling which works by means
of producing a slippery surface that marine gowth cannot adhere to.
The result was fantastic - the prop was still clean a year later as
opposed needing to be cleaned every couple of months in summer.
Propspeed is very expensive but I believe Seajet Pellerclean to be a
similar product and this has just been rated as the best in March
Yachting Monthly and Motor Boat
magazines. Has anyone tried it?
John McDougall

-- In, Claude Roessiger
<nearlynothing@...> wrote:

I have had no end of trouble with this combination.
Amel aren't playing this straight with us. Every owner
I have met with the Volvo-Auto prop combination has
similar woes. I think the source of the trouble is the
prop. In reverse, do you get 3500 RPM? If so, it says
a lot.
This darned prop (and I have had unsatisfactory
exchanges with Bruntons, the maker) is unbelievably
sensitive. Unless it's polished to perfection, it
seems to just not give power. Expensive as it is, I
think to change it.
At full power the SM ought to give you 8 kts +.
I have had similar woes in waves as you describe, no
power, no speed.
The Volvo turbo-diesel is itself less torquey than a
straight old diesel as in the old Maramus,
bullet-proof engines.
This said, an 80 hp engine should do the job. I think
the prop is suspect.
If anyone has made a prop change successfully, it
would be good to know.
Claude Roessiger

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