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it did not go well. In fact it took one and a half days to remove the bow thruster despite being soaked in Corrosion Block and other lubes for almost a week before we tried to remove it. Here is the saga and a sure way to get it out next time.
First we tried the drop method mentioned on this site. The only success we had with this technique was to splinter the trunk fibreglass and remove the skin off my hands!
Then we tied one end of a rope to the thruster just above the gearbox and tied the other end to a 6 foot steel square sectioned tube. One end of the tube tucked under the forward hull support trestle. Downward pressure and several persuasive beatings with a wooden block did move it about 3/16th of an inch but no further. Just enough in fact so that the securing pins would not go back in, leaving the boat unusable. No turning back now. More solvent, more beatings but no more movement. The end of the day came and I retired to bed to lick my wounds and curse this bow thruster even more than I have in the past.
Next morning, thinking that the splines on the drive shaft must have corroded, I decided to dismantle the gearbox so that we could withdraw the tube downwards and the motor and shaft upwards. Having removed the prop shaft and major planet gear wheel, the drive shaft then dropped down an inch, so obviously it was not the splines causing the trouble but the fibre tube stuck to the inside of the motor housing despite being well greased as were the splines when I last serviced the unit.
It was now clear that we had to twist the motor relative to the shaft. To do this, we removed the ant-torque plate from the underside of the motor and repositioned it 90 degrees anticlockwise so that the two prongs faced aft into the cabin. (You will have to move the bolt that does not hold the plate to the motor one step anticlockwise too so that it aligns with the hole in the plate). - For those who do not have this plate, then you are out of luck. It was added to the design after my sinking to stop the bow thruster tube failing. Amel rightly made modification kits for all SM's fitted with the larger motor, and if you don't have one, then I would thoroughly recommend getting one. For two reasons now.
We found a 3 foot tube that fitted over the anti-torque plate prongs and tried to twist the motor against the tube. After a huge amount of effort and and extension bar, we moved it a little then sprayed more lube in though the locking pin holes. Gradually it freed up some more, but the thruster still refused to pull free despite the leverage of the 6 foot bar beneath. After many futile attempts I got the mechanic to twist the motor whilst I put all of my weight on the bar below and eventually we got the bow thruster out. This method will work, providing you have the means to twist the motor.
Examination of the tube revealed no pitting and there was very little rust on the inside of the motor housing. I believe that it was just made too tight. It always was very difficult to locate the tube in the fully home position in the motor housing. There was no rust on the motor lower bearing, or the splines, both being well greased.
As a precaution I have ground out the inside of the motor housing using my Dremmel so that the fit is now more agricultural and less prone to seizure. I will also reassemble it with Corrosion Block anti corrosion grease instead of plain water proof grease once the trunk fibreglass repair is complete. Hopefully such a nightmare will not happen again. Maybe a contributary factor is that since modifying the bow thruster to run in grease with sealed bearings, it has not been necessary to remove it so frequently to get rid of the mayonnaise. The last removal was almost three years ago. (See next post).
Ian Shepherd SM2000 #414 Built 2003 Location Mediterranean
On 18/07/2012 08:17, Bob Parry wrote:
Good luck with it. As you can imagine, the oil in ours was like mayonnaise.
It still worked well and sounded fine but it was probably on a short fuse.
We don't know why it started to leak on our way from New Caledonia but it
seems logical that the seal was somehow damaged when we went to the fuel
dock. Up until then, it had been bone dry.
Hope all goes well. We will be interested to hear how it went.
Ann and Bob
On Wed, Jul 18, 2012 at 5:46 PM, Ian Shepherd <firstname.lastname@example.org>wrote:
I was joking when I said lift the foredeck of course! I was just
imagining the car jack trying to lift it up as it generated pressure. I
hope to start work on the thruster next Saturday when I am back in Cyprus.
As I have filled my thruster with grease instead of oil, it would be
possible to do all the servicing without disconnecting from the motor,
but I know that if I don't get it apart now and re-grease the splines,
then I probably never will. Thanks for the reminder on the neoprene
seal. I will have a good look at that too.
On my first SM I built a rubber dam around the entry area to the inside
of the boat and fitted drain tubes that connected to the anchor locker
drain pipe. This reduced considerably the amount of water ending up
under the floor adjacent to the forward heads.
When the thruster arrangement was re-designed following my sinking, the
later boats have a watertight compartment for the thruster that drains
into the chain locker pipe. End of problem.
I will post my findings when I have dismantled the thruster to see how
the grease worked out. Audibly, it seems fine after almost three years
of use using grease.
Ian Shepherd SM 414 Crusader Built 2003
On 17/07/2012 09:20, Bob Parry wrote:
I don't know what you have envisaged about the process that was used in
Yalikivak but we DID NOT remove the foredeck. They removed the bow
motor to give room to move at the top of the bow thruster (motor washad
dismantled) and the whole thing was supported under the boat push against
the action of the jack. The bow thruster was in the up position and they
jacked the top section upwards, hence the need to remove the motor. We
the boat for 5 years before we managed to get it fixed. We had triedseals
everything including the drop method with the only result being
consternation among other people in the boat yard.
We have a rubber seal as well as the foam ones. It is similar to the
used in irrigation systems and it has the "open" side down to stop inflowNew
of water. Ours had become so bad that we had to put a bulge pump in the
bilge outside the forward head. We have since travelled from Turkey to
Brisbane in Australia and had no water come in until the last leg from
Caledonia. It appears that the seal has suffered some damage. Dare say weby
will find out during our next haul out.
Ann and Bob Parry
On Tue, Jul 17, 2012 at 4:29 PM, Ian Shepherd<email@example.com
Hi Bo& Ann,
thanks for the info. I will try Bill's drop suggestion first before
trying to lift the foredeck! I presume by seal you mean the foam seals
that go around the shaft? There is a correct way to fit them as I
believe that one side is harder than the other. Can you please remind me
of the correct way round? I would assume that the hard side is glued to
the top and bottom of the hole and the soft side faces down and up? Or
is it the other way round?
Ian SM 414 Crusader Built 2003
On 17/07/2012 00:32, Bob Parry wrote:
We had the same problem on our 1990 Super Maramu. It was finally fixed
an Englishman and his Turkish assistant in Yalikavak. They removed the
motor to give room at the top and used a hydraulic car jack. The jack
inside the boat and the Turkish assistant supported the bottom outsidethe
boat. It took a bit of effort but it worked. Whoever serviced it beforewe
bought the boat had put a seal in upside down and the steel rim had
corroded and was holding the fibreglass? tube in a vice-like grip.
Good luck with it.
Ann and Bob Parry
Nowornot SM#33 in Brisbane
On Tue, Jul 17, 2012 at 6:38 AM, sv_crusader<firstname.lastname@example.org
I am having difficulty removing my bow thruster to service it. It
well and truly stuck when I try to pull it out of the boat. I have
the tube/motor housing connection with Corrosion Block and other
in the hope that it will free up in a few days, but I suspect the
splines may be corroded despite greasing them the last time it was
Has anyone discovered a way of freeing up the unit without doing any
damage? The boat is on the hard (at your last haul out spot Bill&
Ian Shepherd SM2000 414 Crusader Built 2003 Med
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