Side Power Bow Thruster Corrosion

[Diverrob]

Hey everyone

I have a Side Power SP 95 Ti and recently had the lower shaft pulled to replace the oil seal. The mechanics found corrosion on the shaft very close to the seal. They replaced the seal which stopped the small oil leak I had but I’m worried about the shaft. Apparently side Power does not sell the shaft separately only the entire lower end. I’m looking for any options I have to fix this without replacing the entire lower end of the thruster. So any options would be helpful, thanks

Rob

 

[O C Diver]

Is the corrosion under the seal area, it looks like it's outside of that? If it's outside of it, I wouldn't worry about it and just make sure the anodes stay in good shape. My experience with my SE100 is that the propeller blades are the fragile components that break when you start the thruster with a fish in the tunnel.

Your lower leg lists for $790 in the USA from the distributor. That includes propellers and anodes which are worth about $200. When I converted mine from 12 VDC to 24VDC, I was able to find a dealer who discounted the electric motor. Maybe you can find someone to give you a better price. While you could probably have a shaft made, there's probably a price point where I would rather pay more and have everything new.

How old is the unit? I'm assuming the corrosion is from use without the anodes?

Ted

 

[Diverrob]

Thanks for the info, the unit is 2007 and I’m not sure why the corrosion happened. Possibly the PO was neglecting the thrusters, and yes apparently the corrosion is outside of the seals as there is no oil leaks now. I will keep an eye out for options and hopefully this won’t get worse.


Rob

 

[C lectric]

You might also contact some machine shops that specialize in marine equipment and ask about metal spraying. Guys that specialize in shafting. You should have a few in your area.

It is a welding technique that can add the metal needed and then they grind the buildup to bring the surface back to specs.
I mention marine shafting as the spray will need to be done with the proper filler metal also.

Examine the shaft for any sign of pitting other than just the roughness from the corrosion. Deeper pitting might indicate crevice corrosion which can literally bore a hole into the shaft eating out a cavity that is very hard to detect from the exterior since the entry hole can be quite tiny.

Without proper zinc mtce. this can happen. THere are other reasons but one biggee is allowing zincs to deteriorate to far. .

 

[Northern Spy]

Looks pretty deep for metal spray, weld build up and turn down, or sleeve. Remember that shaft load is on the outside diameter of the shaft. The starting torque of the motor and the cyclic use in a thruster (on-off-on- off) makes for an interesting problem, although, if the prop is composite and water slips, so the actual load may not be that high.

I'd ask a machine shop to fab one up for you. Probably the fastest and inexpensive solution.

Could even increase the metallurgy at the same time to a duplex stainless steel.

Could be crevice corrosion on the lip seal, could be galvanic corrosion from lack of zinc's, among other possibilities. I've been misled so many times before by what I think I saw. I won't troubleshoot from a photo; even at work.

 

[Diverrob]

Yea I was wondering about spraying metal on as well. Next time it’s out of the water I will take it to get x-ray to see if the corrosion goes deep, then take it from there. Having a new shaft machined may be the simplest in the end though. Thanks for the responses guys, I always appreciate a second opinion.

Rob