Max Power bow thruster CT100 - bent prop drive pin

[ohana]

Hi all

I have a CT100 bow thruster, new with the boat in 2012. Observed the starboard prop had some slight blade damage so decided to remove it to check it over, possibly replace. Removed the grub screw, but prop still refused to be easily be removed. So made a custom prop puller from some scraps of steel, eventually prop came off.

I found that the stbd prop drive pin is slightly bent so will not come out of the shaft in either direction. I have tried gentle tapping, but no success - dont want to hit harder for fear of damaging the shaft bearings. The pin is bent such the old prop (or new replacement) will be hard to push back on.

I have tried using long nose mole grips to put some force on the end of the pin, with the mole grips braced back to the far side of the prop shaft. So far no luck. Obviously, this is all hard to reach as it is in the bow thruster tunnel.

So - first question is if anyone knows of a clever tool or method I could use to remove the pin while the drive leg is still in place?

Second question is if anyone has removed and reinstalled a CT100 thruster drive leg? Is this straightforward to do?  

Thanks

[Charlie-Bravo]

I know little of bow thrusters, but never beaten by a stuck fixing or dowel.
I hear a lot have shear pins, as on out board motors, so a bit odd that your pin is bent, you would have thought it would shear, perhaps the pin just drives on your thruster and there are other sacrificial things to deal with logs jamming the props, or a clutch perhaps.

Is the offending drive pin located in a ‘through’ hole? if so punching it out with a proper punch would seem the best approach , given room.
Diameter and length of the pin? is it possible to saw a groove or two in the exposed areas to enable a better grip, then  grips and wedges to pull the pin, it can’t be too hard a material to saw if it bent.
Available room for attack? there are small stud extractors that will grip and turn the pin …… but only if there is room to operate, and they won’t pull it out but might loosen it .

Ideally one would heat the shaft to loosen the pin and would drift it out with a punch , but I guess flames in a restricted area near a combustible boat could be a no no, and the amount of dis assembly might be off putting.

Hope the pin gives up soon.

CB

[ohana]

Hi, thanks for your reply. Like you, would have thought the pin would shear as a fail safe, but looking at the port prop pin (which is unaffected) it is just a plain pin, with no groove round the circumference whioch I have sometimes seen on outboard shear pins. It is only slightly bent, but sufficient to prevent it coming out.

It is located through a hole in the drive shaft. It is in the thruster tunnel, circa 200mm wide so access is a real issue. If I take the drive leg out to a workshop, removing the offending pin would be simple, its all made difficult by access. There is no room for a manual saw, perhaps room for a small powered saw or disc cutter, but lack of access and viability could easily lead to damage to other parts of the drive leg.

I am increasingly of a mind that I will need to remove the leg from the boat to do this safely and properly

[Charlie-Bravo]

Just one further thought.

How about drilling a pin diameter sized hole into a square bar , lower onto the exposed pin and turn the bar with a spanner in an attempt to straighten the pin ? 
Guess you would have to dream up a way of stopping the shaft going round, but that might be an easier challenge.

Good luck
CB

[ohana]

Hi, thanks, thats a really good idea - will have a go!

[Zanshin]

I head to my boat and my "broken" Max Power bowthruster next week. I got the propellor pins as spares and they are REALLY massive and I don't know how they could be bent without snapping the props off! But I'm worried that I'll encounter the same or similar problems. Hopefully ohana will get this fixed first and I can learn from experience...

[ohana]

So even some wide jaw mole grips could not shift the pin! So I have dismantled the bow thruster and removed the drive leg from the boat - its now in my workshop. 

EDIT - I have now removed the pin, drove it out with a punch with the prop shaft fully supported. There is no way O could have done this in-situ.  

Removal of the leg was reasonably straightforward, so now need to get some spare parts!