Re: [Amel] Re: bow thruster service

Ian Shepherd

I am confused by this. Whether the locking pin is in or not will not
affect seawater getting through the lip seal on the bow thruster prop
shaft. It may well affect whether sea water enters the boat if the
compression of the seals around the tube where it enters the hull is
marginal. When did you actually last check the gearbox oil? Can you be
sure that water has not entered the oil in the past two years? It will
depend on the amount of use of course.

Like you I leave extension to the very last minute. My prop losses
occurred due to torque not fouling lines. The original nylon holding
screws were a mix of small and larger ones. They were inadequate for
the more powerful electric motor that was fitted to later SM's.
Following discussions with Jaques Carteau the design was beefed up by
making all the screws the larger size. Since then I have never lost a
prop. Fishing line can be as big a hazard as rope.


Ian Shepherd SM 414 Crusader

On 07/03/2011 01:52, murray k. seidel wrote:

Sundance SM349 bow thruster has had some water in the oil, and two
years ago
I replaced the seals. But I have never have any leak since then.
Before that
seal change, the seal had not been changed since construction in Jan.
I have owned since Oct 2005 and the only time they leaked was when I
to put the locking pin in on the way to Bermuda from Wilmington. I
discovered my error, put pin in and no more leak. Because it is a drop
unit it is more vulnerable, which is why I put mine down only a short
distance before I need it after a quick scan ahead. Don't forget, a
through-hull thruster can also suck up lines and is harder to repair.

<>] On Behalf Of Dimitris
Sent: Sunday, March 06, 2011 12:53 PM
Subject: RE: [Amel] Re: bow thruster service

The main reason I decided to change the boat for an Amel 54 was the

It is a source of problems the only good thing is that you can repair it
easily without spare parts from Amel.

But it is very sensitive and dangerous to approach harbours with free
mooring lines and plastic bags afloat.

<> ] On Behalf Of <>
Sent: Sunday, March 06, 2011 9:16 AM
Subject: Re: [Amel] Re: bow thruster service

The bearing are corroded it is almost IMPOSSIBLE to make the bow
thruster tight and more or less sea water pollute the oil
This AMEL bow thruster is a technical sum of non sens, approximations
and many many different problems for the owners ....
I would like to know how many SM have a tight bow thruster

Le 06/03/2011 07:34, amelliahona a écrit :


As per our several discussions via private email, the bearing in the
base of the motor that supports the spline shaft is an NSK 6204VV
bearing. Evidently the 6204 bearing size is very common and the VV
means that the bearing is sealed with a rubber seal on each side. The
bearing is a Single Row Radial Bearing; 20 mm ID x 47 mm OD x 14 mm
Wide; Double Sealed, Non-Contact; C3 Clearance.

I was able to purchase a couple on ebay at the following link:

Price is $6.99 US each and the seller will ship internationally.

Extraction of the bearing and replacement is another issue. When you
have accomplished the task please write it up and post it in the Files
Section of the forum for the rest of us. Also, you could upload your
photos to the Bow Thruster Service File in the Photos Section. I think
they would useful to encourage everyone to annually service this area
and take care of corrosion control.

Best of luck,


--- In <>
< <>>, " <mailto:gtesta23@...>
< <mailto:gtesta23@...> gtesta23@...> wrote:

Hi Bill and Gary,
sorry I don't understand : among the photos " Bow thruster service"
I see a ball bearing rusty brown, it seems broken or it is only very
dirty ?

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