The Bow Thruster Project - Part 12: Thruster Installation Complete!

We can finally say that Bandit's new Side Power SE40/125S electric bow thruster is now fully fitted!!

We came down early this morning and set about drilling the holes in the GRP tunnel for the lower unit. Things went smoothly, all but quite a bit of swearing. We absolutely slathered a thick bead of Sikaflex on the gasket both sides before fitting the lower unit to the tunnel so we can be sure that it will all be watertight and will remain watertight for a very long time (hopefully). The motor bracket went on perfectly and we bolted the lower unit to the tunnel. It was then time to see whether we had measured and drilled the holes correctly. Thankfully, the newly developed Side Power Q Prop slid on brilliantly with an even clearance from each blade to the tunnel. It couldn't have gone better.

Cutting holes...scary stuff
Plenty of Sikaflex!
Front view of lower unit and Q Prop
Rear of the lower unit and Q Prop

We then fitted the motor and wired it up. Then came the final test. Would the motor work or had we done something wrong in the process? Not that I expected anything to go wrong but you never know and it's a scary moment to finally see if something you've fitted works or not. Good news! The LED indicator on the control panel at the helm lit up and a very quick flick of the switch showed everything works correctly. The propeller spins freely and it sounds incredibly powerful, although having a smaller tunnel and propeller compared to competing thrusters. The salesman at SBS16 where we purchased the thruster ensured us that we will get the same, if not more, power from this smaller tunnel and prop due to new motor and prop technology developed by Side Power.

A quote from Side Power explaining the new development of their new Q Prop: 'The new 5 blade special skew propellers are the result of over 2 years of development work and thousands of tests. They have been designed to reduce the noise level while maintaining the exceptional efficiency of the old 4 blade Side-Power propellers. This goal was achieved, and we even chose to make them a little bit more aggressive on some models, increasing the thrust on some thrusters about 5%'. Sounds interesting and we keep our fingers crossed for some good performance!

After fitting the thruster and tidying up, I replaced all the cushions so Bandit looks more like a clean boat again. It's horrible having fiberglass shavings and tools scattered everywhere... We will need to remove it all again before she goes back in as the boatyard has said they will check for any water leaks from the tunnel and thruster when they slip her back in, which is very kind of them as we probably won't be around for the slip in.
Back to normal

In addition, we have heard news that our rear propellers from both drives have been sent off for refurbishment. Sadly, due to the Christmas post and Christmas closing times, we have been told that the propellers might take as long as four weeks to return to us. This is a lot longer than we had imagined so Bandit will have to be slipped in, when we've finished what we plan to do, without her propellers on. She will then have to be hauled out for a second time soon after for the marina to refit the propellers for us. Not great news but not much we can do...

The last jobs of the day were to generally clean up, scrape off any further loose antifouling on the waterline and polish the hull. A very productive day and it's nice to think the thruster is in and ready to be used! Happy days!


  1. Thruster lower unit fitted using lots of Sikaflex marine sealant
  2. Motor bracket fitted and bolts tightened to correct tightnesses
  3. Electric thruster motor fitted and wired up to battery
  4. Thruster testing - all is good and circuit breaker functions properly
  5. Scraped off any remaining loose antifouling
  6. Gave hull first coat of polish - several more to do
  7. General tidy up of boat inside
  8. Fitted red circuit breaker knob with new M8 connector


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