RE : [Amel Yacht Owners] Engine-Autoprop problem

Patrick Naegels <naegels@...>

Hi Amel owners,

I confirm what said Joel. The Autoprop is very sensitive to any foul,
due to its independent blade spin. On Caramel, we clean each blade every
month with a simple scraper, and eventually with fine sandpaper.

Easy to do underwater, but with diving tanks or respirator-compressor.
Really hard to do properly if snorkeling.

Patrick Naegels - Caramel (SM329)

-----Message d'origine-----
De : Joel F. Potter []
Envoyé : vendredi 6 août 2004 17:15
À :
Objet : RE: [Amel Yacht Owners] Engine-Autoprop problem

Dear Dimitris:

What I am about to relate may seem hard to believe but it is absolutely
true. A few years ago I had symptoms exactly identical to yours. I had
fuel tested, tested flow rates on my Racor filters and had the best
man in town check my engine and fuel system. All was O.K. Believing
any repair would be a dreadful ordeal, I called Jacques Carteau at Amel.
enjoy a good relationship with Jacques and he gets great pleasure out of
teasing me. When he told me to clean my propeller I was sure he was
He insisted and told me that the AUTOPROP is particularly sensitive to
GROWTH, even a small amount. Feeling ridiculous and being certain I was
victim of a joke, I dove on my boat and, believe it or not, there were
several small gooseneck barnacles, most of them on just one of the
I cleaned them off and used sand paper to polish off their "footprint".
engine problems disappeared immediately.

How can this be? To make a long story short, the AUTOPROP works as well
it does and is extremely efficient due to the unusual shape of the
blades. The blades, though not interconnected must work in complete
symmetry/unison. If any one blade is more fouled than another, that
it's "pitch" or angle of operation. The vortex of water coming off this
blade then causes the other blades to change's complicated
but I
hope you can understand the relationship.

I hope this will eliminate your problems. Remember, the prop must be
perfectly clean on all three blades. As a proof to this, last week I
an 8 month old SUPER MARAMU that sat at a dock here in Fort Lauderdale
two months. When we pulled the boat out of the water, the propeller was
fouled, but pretty evenly on all three blades. The boat would only go 4
knots at 2000 max R.P.M. and there was a noticeable increase in
Once clean, all was normal.

Let me know how you solve your problem, please.

Good luck!

Joel F. Potter


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