Originally Posted by Rollysflyinghigh
Our Bow thruster will not engage.
We can hear the Motor try to engage BUT it will not turn.
If the motor does not turn, does your thruster circuit breaker open? Or does the motor spin freely, but the propellor provide no thrust?
During the Winter months I start the engine once /Month and turn the thruster on to keep the passage clear.
I dove in the drink to clean any debris/mussel/growth.
And presumably, you've tested the thruster immediately AFTER verifying the tunnel is clear?
Thoughts on popping the motor off and doing a dry test?
Yeah, lots. This is a VERY bad idea.
Any issues with taking motor off while boat is the the water?
No. Removing the motor is difficult but not impossible, due to clearance issues. However, the gearcase provides a watertight boundary with the interior of the boat. You can remove the motor while the boat's afloat.
IE is this a "on the dry" issue?
Not necessary, but can be if the gearcase has failed.
Is there a spot from inside the hold where one can spin the drive with a wrench?
No. You can attempt to rotate the driveshaft on the gearcase with the motor removed, but a free-spinning drive shaft does not necessarily indicate the gearcase has not failed. Only observation of the propellor while manually rotating the propellor can verify the gearcase integrity.
Thank you in advance, from Salt Spring,
Hi Mark. I believe your thruster is likely a SidePower 4hp single-propellor unit. If so, there is a shear pin on the motor shaft that provides torque to the gearcase and propellor. If your motor spins freely when you engage your thruster, but you observe no thrust, then this pin has likely failed, or (much less likely), your gearcase has failed. SidePower provides instructions, and appropriate part numbers, on how to replace this pin. Yes, it can be done in the water, as the gearcase provides the watertight seal to the interior of the boat with the motor removed.
Don't be fooled into thinking this is a "simple" fix, or any old steel pin will work to replace the OEM shear pin. Access to enable replacement of this pin is difficult, as the thruster motor must be removed, and the space is tight on the Pacific Trawler 37. This pin is manufactured from properly-tempered steel, and has a subtle taper to enable it's proper installation. I suggest you use an OEM shear pin for this replacement operation, seat it properly, and use Locktite to ensure it stays in place.
However, if you motor fails to spin when you engage your thruster, AND you're positive the thruster tunnel is clear, you either have a failed motor, or possibly a poor electrical connection to the motor. The obvious first thing to check is your 12vdc battery cable connections to the thruster motor, to ensure they are clean and tight, and you actually have ~13.2VDC at the motor input. Next, verify your control electronics are also clean and tight. If all appears good to go, but the motor will not spin when mounted onto the gear case AND the thruster circuit breaker has not opened, then it's likely your motor itself is faulty.
It is a REAL BAD idea to remove the motor, and attempt a "spin test" by engaging the thruster control. All DC motors produce essentially infinite torque at zero rpm, and it's a very bad idea to hand-hold a 4HP DC motor while attempting to restrain the inertia of the case at startup. The motor will likely jump out of your hands and make a giant mess, or possibly injure you. MUCH better idea to remove the motor from the boat and take it to a local electrical motor shop for testing.
Ditto on general R&R of this bow thruster assembly. Far better to get a trained mechanical technician from a local boatyard to check this thing out for you, particularly if this is your first time investigating this problem. In my opinion, bow thrusters are not particularly DIY-friendly, as troubleshooting is not trivial. And trust me here-a 4HP DC electric motor is WAY more powerful than you might suspect. Personally, I treat them with great respect.