Side Power Bow Thruster

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ttles714

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My 2007 Marlin has a side power bow thruster that runs but does not turn the propeller.. Does anyone know what model Grady would have installed in this boat ? It is in a tunnel at the bow and has a single propeller. I tried getting the 3/4 lock nut off the propeller shaft but it just spins the shaft .. Any help or suggestions would be appreciated.
 
I think those have a key between the motor and propeller shafts. May be sheared.
 
when I loosen the nut holding the prop, the whole shaft spins .... Is the key inside the hull or between the shaft and the prop?
 
If you are saying the the shaft can turn without the prop turning, that is a problem. There should be a key that sits in a slot on the shaft and a slot inside the center hole of the prop, In other words,
 
What model SidePower thruster do you have? SidePower does not have a shear pin on the back side of the propeller. Instead it is under the electric motor and drives the lower unit.

Screenshot 2025-07-27 at 9.02.34 PM.png Screenshot 2025-07-27 at 9.03.06 PM.png
 
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Going from faded memory and not sure the models are the same, but the one I had on a Back Cove you pulled the motor from inside the boat to access where the key is (was).
 
seasick said:
If you are saying the the shaft can turn without the prop turning, that is a problem. There should be a key that sits in a slot on the shaft and a slot inside the center hole of the prop, In other words,
Click to expand...
I think I am off base with my answer based on others responses. I should have known that the shear pin or mechanism is not in the prop hub. Bad dog , no biscuit
 
seasick said:
I think I am off base with my answer based on others responses. I should have known that the shear pin or mechanism is not in the prop hub. Bad dog , no biscuit
Click to expand...
On my Vetus bow thruster it is behind the prop in the lower unit. This is where it should be on all bow thrusters. Pulling the motor must be a pain.
 
I have a side power with sleipner motor... def check the sheer pin under the motor... but there is one on the back of the propeller itself too. I don't know if it's actually a sheer pin or just some pin to help locate the prop on the shaft but it's there.
 
Here’s a video of replacing the motor shaft key. Dont know if it applies to your model but the one I had was similar to this. Video guy is a bit cumbersome but you get the idea.
 
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