Max Power CT100 Bow Thruster - bent prop pin

[West Coast]

Hi all

I have a Max Power CT100 bow thruster, new with the boat in 2012. Observed the starboard prop had some 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. The bent pin was the reason why the prop would not easily come off.I have tried gentle tapping of the pin, 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 to push it out, 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, circa 200mm dia.

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? The drive shaft is 14mm dia, and the pin is set back 35mm from the end of the shaft

Second question is if anyone has removed and reinstalled a CT100 thruster drive leg? Is this straightforward to do? The bent pin could easily be removed if I can remove the drive leg and take it to a workshop.

Thanks

 

[Keith-i]

I would have thought the pin was made of a fairly soft metal as it’s meant to be sacrificial if the prop jams. Would not some bending back and forth snap it off? As to removing the gearbox that’s fairly easy. I fitted a Max Power thruster a couple of years ago. Unbolt the motor and you will see a couple of screws that hold the gearbox on. Undo these and break the sealant bond between gearbox and prop tunnel and it should all come away.

 

[Stemar]

I would have thought the pin was made of a fairly soft metal as it’s meant to be sacrificial if the prop jams.

Me too. I'd be inclined to cut the worst bent end off flush and drive it out with a punch.

 

[West Coast]

Hi, thanks both for your reply.

I would have thought the pin would shear as a fail safe, bit like an outboard prop, but looking at the port prop pin (which is unaffected) it is just a plain pin, with no groove round the circumference which I have sometimes seen on outboard shear pins.

Keith-i, Thanks for your encouraging comment re dismantling and removal - I am increasingly of a mind that I will need to remove the leg from the boat to do this safely and properly

 

[Plum]

Hi, thanks both for your reply.

I would have thought the pin would shear as a fail safe, bit like an outboard prop, but looking at the port prop pin (which is unaffected) it is just a plain pin, with no groove round the circumference which I have sometimes seen on outboard shear pins.

Keith-i, Thanks for your encouraging comment re dismantling and removal - I am increasingly of a mind that I will need to remove the leg from the boat to do this safely and properly

I have been doing some research on bowthrusters and I have not seen any claims from any manufacturer that their drive pin is a "sheer pin" designed to protect the prop.

 

[West Coast]

I have been doing some research on bowthrusters and I have not seen any claims from any manufacturer that their drive pin is a "sheer pin" designed to protect the prop.

To be fair, Max Power dont seem to claim that the drive pin is a fail safe, but given the damage to the prop blade, had wondered if this might have been a good idea to safe the prop

 

[david_bagshaw]

Have taken off a vetus thruster, I imagine this is very similar, just a couple of Allen headed bolts, and a rubber gasket on one side and a fibre one under the motor holding cage.

 

[West Coast]

An update - I tried using some larger jaw mole grips to push the pin out but no success. So I have dismantled the bow thruster and removed the drive leg from the boat - its now in my workshop. Will take some photos and post them

EDIT - photo now included, pin is 3mm dia for reference. The keyway in the plastic prop is widened a bit and one of the prop plades has a chip in it.