Sleipner / Imtra Side-Power SP-75 Bow Thruster Service & Repair

Servicing the Brushes
Annual Maintenance
Troubleshooting Guide
Troubleshooting Tips

I have recently noticed that our bow thruster was down on power.  It makes this screeching noise too when I was driving it to either side. We've had several instances where we weren't able to get the bow around into the wind and I didn't remember it being like that before.  Being down on power is kinda subtle because we're dealing with a 30,000 pound blob sitting in the water and we're trying to rotate it with a six horsepower electric motor.  Not really instantaneous, if you know what I mean.  It took me a while to get around to servicing it but I finally did.  I replaced the lube and even modified it by cutting the filler tube and putting in a screw-together connector so it'll be easier to drain next year.  I pulled the motor and carried it out to the dock where I blew it out using a can of compressed air.  There was quite a bit of carbon dust built up in there!  Once I had the motor blown out I removed each of the four brushes and inspected them for damage.  They all looked good, had plenty of life left in them and the springs all had about equal pressure.  So far, so good.  Next I carefully filed out the buildup inside the brush holder to ensure the brushes had free movement.  I blew out the whole thing again and reassembled it.  With Cheri at the helm while I watched for arcing and sparking, we fired up the engine and ran the bow thruster controls back and forth in short 5 or 10 second bursts.  Big difference!  That baby was thrusting our bow all over the place!  And no screeching either!  Woohooo!  Total success!

I've attached links to several good resources at the top of this page.  They're good for general purpose servicing even if the model is different.