As I understand what you wrote about the bow thruster you added a sleeve in
the shaft that is connected to the prp and replaced the bearings with sealed
bearings and then packed the gearbox with grease.
Why can you not add oil from the top of the bow thruster?
Amel Super Maramu #376 Kimberlite
[mailto:amelyachtowners@...] On Behalf Of sv_crusader
Sent: Saturday, July 03, 2010 12:56 AM
Subject: [Amel] Re: Modifications
the stainless bush was an exact copy of the bronze one, except that it was
made with three grub screws instead of two to allow better centering.
Assembled with grease there are no signs of any Galling after over three
years of use. In fact both the shaft and the bush look as new.
I am off for 10 weeks sailing this morning, so will be unable to reply
further until I find a wireless network to log on to, but I will be glad to
discuss further when I get back.
Ian SM414 Crusader (Headed for Mersin Eastern Turkey)
--- In amelyachtowners@...
<mailto:amelyachtowners%40yahoogroups.com> , Richard03801 <richard03801@...>
Thanks for the info. One question how much clearance did you plan between
the shaft and bushings? Metal to metal ss to ss normally does not work well.
If they touch they will Gaul as the bronze is used as a bearing surface. It
may be that the bearing pack is stiff enough to hold the shaft from
moving/touching. I guess time will tell.
Sent by Richard Piller
On Jul 1, 2010, at 5:55 PM, Ian Shepherd <sv_freespirit@...> wrote:
I read recently that owners modifications can be detrimental to the
original concept. Maybe so, but here are three modifications that have
definitely improved my boat.
Three and a half years ago I replaced the bronze main engine prop shaft
bush with one made of high grade stainless steel. I recently hauled for
the first time since fitting it and there was absolutely no wear
whatsoever on the bush. Just a very slight polishing of the surface
where the lip seals mate to the bush. There was no noticeable wear to
the seals either after 600 hours of motoring, but I changed them anyway.
This contrasts markedly to the normal wear experienced on the standard
bush. I believe that the maintenance interval is now much longer with
the stainless bush, and there is a worthwhile long term cost saving too.
I replaced the 70M of chain supplied by Amel with 90M. There was a
noticeable improvement in the boats motion particularly in short seas.
The boat pitches less, hardly ever slams any more and because of this
maintains a higher average speed. I also have 10M of chain and 100M of
rope for my second anchor stored in the forward locker together with my
two Fortress anchors, so in reality, I have the equivalent of 100M of
10mm chain in bow. The extra weight forward certainly seems to be for
I decided to try and improve the lubrication of the bow thruster, which
seems to have more sea water inside it than oil most of the time. The
arrangement of a single lip seal over a rough fibre shaft is hardly
conducive to keeping the sea water out. I removed the shaft and had it
machined down to accept a thin stainless sleeve for the lip seal to run
on. I then replaced the three open ball race bearings, which were all
rusty, with sealed bearings running in their own grease. Of course this
prevents you pouring the oil in via the top of the tube, so I decided to
not use oil to lubricate the bevel gears, but instead use water
This was packed into the gearbox housing before the back plate was
refitted, leaving a small gap to allow for expansion, and grease was
also placed between the outside of the outer bearing and the lip seal.
This was done about four months ago, and the bow thruster has never
sounded sweeter. Gone is the awful sound of bearings running is a sea
water emulsion, and there does not seem to be any loss in power either.
Time will tell, and I shall remove the bow thruster this winter to see
if the modifications have had any adverse effects on the gears, but it
is my guess that the life of the seal, bearings and bevel gears will be
As they say, cruising is fixing things on water. Anything that reduces
wear and subsequent failure must be for the better.
Ian Shepherd SM 414 Crusader