Lewmar bow thruster not working

[grahamdouglass]

In June of 2018 I had a Lwemar 185 12v Bow Thruster installed in my Marine Trader 41, 15 ton boat. In March of this year I went to test it and made a weird sound and the motor raced.

I lifted the motor and the shear pin is fine. The motor works fine.

The bottom was done in June 2018 when the thruster was installed. I didn't really want to haul my boat this year so I will probably get it done next year. I lived without a bow thruster for 10 years so it won't kill me.

I suspect mussel growth may have jamed the propeller. Its been one of those years where the boat hasn't got out much and I've been too busy to do any thing on the boat.

The question I have is.
1) How often do bowthrusters fail?
2) Are mussels a real problem, and can mussels 'break' a thruster?
3) Before testing a thruster each spring, is it advisable to power wash
the thruster hole to remove mussles? Should I put the boat on the
tide to inspect the thruster before I try it out?

I've never heard of a thruster problem in salt water. A failure after 2 years is pretty expensive.

So all you thruster owners out there chime in and give me your thruster experience and advice. The guy who installed the thruster said he couldn't believe it broke.

 

[Chrisjs]

When you refer to the shear pin being visible when you lift the motor, where is it? Not sure my Vetus had a shear pin visible like that - if it did I never checked it! However it did have pins holding the prop(s) onto the horizontal shaft in the tunnel. If you had excessive growth in the tunnel when you launched, I can see how that could have jammed the prop(s) and possible broken the pin(s) holding the props to the shaft. In that case, you likely lost your prop(s) and the motor is running fast because there is very little friction (work being done) because there are no prop(s) moving water. Time to go for a swim and check it out!!

 

[grahamdouglass]

The motor sits on the propeller assembly atop the tube. Between the motor and the propeller assembly is a shear pin.

I was talking to a technician at the club and he said the propellers some times fly off, so I guess there is a shear pin at the propeller area also. You would think there would be a retainer clip to prevent the propeller from flying away.

Either I have to go swimming or put the boat on the hard to do a visual exam of my thruster tunnel.

 

[caltexflanc]

Any kind of fouling of the prop can render a thruster useless, even if it is spinning. Are you saying it sounds different now than when it was operational? Was 2018 the last time the bottom and running gear were cleaned? Might be cheaper to have a diver take a look vs hauling the boat.

 

[Solly]

First thing to do is dig out the paperwork and see how the prop is connected to the shaft. If there is a pin there that would be my guess. Could be the shaft or it could be the gear.

For some reason barnacles seem to love my thruster tunnel. Cover the tunnel, shaft, and the props. Each spring I take the props off , scrape everything, and paint anti-foul on it all.

 

[grahamdouglass]

That’s a lot of work to do for a thruster each fall and spring. Cheaper than the alternative. Right now I am debating as to what colour swim shorts I’m going to be wearing when I go for a swim to look at my thruster tunnel. It’s going to be cold. Or I could put it on the tide grid and take pictures.

 

[oscar]

First thing to do is dig out the paperwork and see how the prop is connected to the shaft.

When all else fails read the instructions.

 

[Solly]

Right now the jelly fish are so bad in the Chesapeake I'd need a full rubber suit b-4 I'd go in.