Topics

Bow Thruster Siezed

Ellen Cahill
 

Hi everyone! 

I was hoping somebody could help with a particularly troublesome bow thruster. We bought out Mango 3 years ago and we have been doing short sails while slowly refurbishing her. 

We have a number of times attempted to remove the bow thruster foot assembly to no avail. This past winter it started leaking so now it has to be removed to replace the seals. I've no idea if the previous owner had ever removed it.

We have removed the 4 bolts but the shaft is jammed in the rust encrusted top motor assembly. We have since
- applied vibration with a sander
- sprayed penetrative oil in the 4 holes (every day for a week)
- tapped with a hammer
- dropped it about 10 times
- put a stick between the bottom v section and the hull while jacking up the motor assembly from the inside. Slowly applying more press and oil over a week.

It hasn't moved at all. The leak is unacceptable so we are now considering cutting the shaft or motor holder. Really not ideal. 

Anyone have suggestions of what to try next? 
What is the black shaft made from?  What's inside the composite shaft?
Can you buy this foot assembly from Amel? Idea on cost?

 Thanks for any help! 

 

I saw your photo with the jack pushing the coupling upward. Am I mistaken that it has moved 6-8mm?

This should be a warning to everyone with a bow thruster prior to the Side-Power in A-54's that service on this valuable component is important. I recommend service every 2 years.

Back to your issue. Of course, I do not know all of the details and long-distance diagnosis is problematic, but here are a few things that you may not know:
  1. That bow thruster tube is probably impossible to get at any price. It may be possible that Amel will either have one sitting on a shelf or make one. I doubt it, but you should write and ask SAV"at"amel.fr.
  2. Later model bow thrusters had a 60mm composite tube. Amel fabricated a 60mm tool for the purpose of removing a stuck tube from the motor base of later model bow thrusters. It is possible to make your self or get from Amel when they reopen from the current shut down.
    image.png
  3. The most important thing you need in this process is patience. How long have you left the jack under pressure?
  4. Don't use heat as you will likely damage the tube and of course cutting it will put you out of service forever.
  5. You might consider sealing the bow thruster from the outside with resin and glass which you remove later when you have a solution.
  6. There is a high-carbon steel shaft inside the composite tube.
  7. You might want to look at the high-quality photos here:  http://nikimat.com/bow_thruster_overhaul.html

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar
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On Sat, Apr 4, 2020 at 10:29 AM Ellen Cahill <ellencahill@...> wrote:
Hi everyone! 

I was hoping somebody could help with a particularly troublesome bow thruster. We bought out Mango 3 years ago and we have been doing short sails while slowly refurbishing her. 

We have a number of times attempted to remove the bow thruster foot assembly to no avail. This past winter it started leaking so now it has to be removed to replace the seals. I've no idea if the previous owner had ever removed it.

We have removed the 4 bolts but the shaft is jammed in the rust encrusted top motor assembly. We have since
- applied vibration with a sander
- sprayed penetrative oil in the 4 holes (every day for a week)
- tapped with a hammer
- dropped it about 10 times
- put a stick between the bottom v section and the hull while jacking up the motor assembly from the inside. Slowly applying more press and oil over a week.

It hasn't moved at all. The leak is unacceptable so we are now considering cutting the shaft or motor holder. Really not ideal. 

Anyone have suggestions of what to try next? 
What is the black shaft made from?  What's inside the composite shaft?
Can you buy this foot assembly from Amel? Idea on cost?

 Thanks for any help! 

Trevor Lusty
 

Hi Ellen,
             There might be another way, but you will need a lot of time energy and patience. The bow thruster on my SM jammed solid a few years ago in Mexico and it would not move. After several days trying to get it out, It became obvious that any more dropping or hammering was going to damage the boat.
So, I removed it complete with the motor stuck to the shaft from the inside of the boat. It took a full three days, dawn to dusk to remove and replace.
The complete unit weighs around 80lbs . You need to be really careful to mark all the electrical cables as on the SM there were lots of black ones!
If you consider going this way, be sure that all power is isolated.
The position of the limit switches is really important to ensure that the bow thruster will retract properly when serviced and replaced.
It is a nightmare of a job but it can be done.
When we finally got it out it couldn't be pulled or pressed apart, so it had to heated to white hot before it broke apart.
Bill  has Kindly renewed my membership in the hope that this message may be of some help to you.
Good luck.

Trevor Lusty
Former owner Seafever of Cuan
SM 425
Ireland

Craig & Katherine Briggs
 

Hi Ellen,
In addition to what you're doing and Bill Rouse's suggestions (sans Amel tool) I was finally successful by using a chain wrench around the motor flange along with a 2' extension pipe for added leverage. I would torque it in one direction and apply as much force as I thought it would take. Then I'd reverse it and twist the opposite direction. After several repetitions it finally budged just a fraction. After more back and forth repetitions and it came free. I used that technique on mine and also another Santorin - worked very well.
Good luck with it!  Craig

eric freedman
 

HI,

When you eventually get the thruster apart,. I would suggest you take the motor to a rebuild shop. . There is an open roller bearing at the bottom of the motor where the tube enters the motor. I would bet you that that bearing is also terribly rusted and needs replacing. I would have the motor gone over while you have it out.

 

About every 8 months I drop the bow thruster enough to grease the spline on the bow thruster and put a bunch of grease up into the receptacle for the spline.

18 years and it drops out like a cannon ball.

 

In addition you can replace the lip seal and donuts that are inside the boat if it looks like it need it.

 

Fair Winds

Eric

Amel Super Maramu #376

 

 

From: main@AmelYachtOwners.groups.io [mailto:main@AmelYachtOwners.groups.io] On Behalf Of Craig & Katherine Briggs SN 68 Sangaris Tropic Isle Harbor, FL via groups.io
Sent: Saturday, April 04, 2020 1:12 PM
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] Bow Thruster Siezed

 

Hi Ellen,
In addition to what you're doing and Bill Rouse's suggestions (sans Amel tool) I was finally successful by using a chain wrench around the motor flange along with a 2' extension pipe for added leverage. I would torque it in one direction and apply as much force as I thought it would take. Then I'd reverse it and twist the opposite direction. After several repetitions it finally budged just a fraction. After more back and forth repetitions and it came free. I used that technique on mine and also another Santorin - worked very well.
Good luck with it!  Craig

 

Hi,

I made this piece 2 years ago for a client, it s easy to made. If you need it look for someone with a milling machine and lathe and it can be easly done.



you can see the problems he had here https://youtu.be/PQnbk4maV4Y?t=440

Alem
Pablo Carmona
SM 253
Spain

Ken Powers SV Aquarius
 

Hello,

This video shows my rebuild of the bow thruster.  If you can't get the lower unit to disengage using all the tricks from other Amel Owners, you can do this for a last resort.....

Here is a link to my video.

https://www.youtube.com/watch?v=F-xWzNfnWLw

If you boat is out of the water you may be able to do the following...  If in the water you can do this under water in scuba gear, will be difficult but doable..

1. Drop the bow thruster
2. Remove prop
3. Remove the hard filler covering 4 screws - at 6:05 minutes
4. Remove 4 screws holding back plate in place.  at 6:15 minutes
5. Remove the main gear and shaft.  at 6:44 minutes
6. Remove the bolt at the bottom of the shaft holding the small gear in place. 6:59 minutes (make sure you have something holding up the tube until you are ready to drop it)
7. The lower unit should now come down without the shaft.  (don't drop any of the parts if you are under water.)
8. Now with the shaft visible, and hopefully you will have an easier time getting it loose from the motor.

This may or may not work.  But, I think it will.

Hope you don't have go down this path, but it might be your last option.

Ken Powers
Aquarius SM2K #262
Currently stuck in Thailand

Ken Powers SV Aquarius
 

Hello again,

Be aware that if you try my (Last Option) , and you still have oil left in your bow thruster it is going to leak all over the place when you remove the backing plate.  Be aware and minimize the mess.

Ken Powers
Aquarius SM2K #262
Currently in Thailand

Ellen Cahill
 

Today was a big day, it came out! 

The boat was on a pier that dries out, so made it easier. I secured block of wood inside around the shaft. Then below the boat lifted up the thruster and pulled down. I had tape around the shaft and after about 20 goes it started to slide out. Bill noted that it appeared to have come out somewhat previously, I wasn't sure about this as I hadn't marked it properly from the get go. But I think it was likely a combination of  multiple attempts and lots of lubricant. 

Time to take it apart, empowered with Kens video. Thanks everyone!

Ellen
Saol Nua
Amel Mango #45

Craig & Katherine Briggs
 

Hi Ellen et al,

Congrats - super that you got it out. 

Your method and that in Ken's video, with the special tool he had made, both rely on just adding force (and/or shock) to pull the tube straight out (down). My experience with a few of these really stuck units is it is really helpful to add a rotational force, not just a straight downward pull.

Using a chain wrench around the motor base, with an extension pipe for added torque, let's you rotate the motor (just a bit at a time) on the lower tube. With lots of lubricant and lots of patience and going back and forth it will finally break free without the drama of slamming it up and down against wood blocks or the frustration of the tool sliding down the tube. You do it with the unit fully retracted such that when you torque the motor the rotational forces are taken up by the structure of the hull cavity and the bow thruster's bracket.

It's much like any pipe "stuck" in a socket - turn it back and forth to release it - don't just try to pull it straight out.

Another version of this I just did with good success was to just operate the bow thruster repeatedly to port and then to starboard in short bursts. (Of course, the retaining bolts were out and a hose clamp (Jubilee clip) was in place.) That torqued the motor back and forth with great force and the tube slipped out easily. (Granted, it was not "hard" stuck".)  It would likely work best in the water with the added torque resistance of the prop.

Lots of ways to skin a cat.

FWIW, Craig