Stern Thruster Problems

[downey]

My stern thruster quit on me the other day. So I assumed it's a shear pin and I pull the thruster, and the shear pin was good.
While I had the thruster motor off I checked the shaft and it turned freely.
I called PBH and I was told to check the fuse, which was gone, (next time check fuse 1st).
So I replaced the fuse, thought all was well, nope worked for less than 1 second and blew a 2nd fuse ($25 each).
So I thought it must be something in the tunnel/prop, so I pulled my boat out of the water, nothing there, and prop turned freely.
Bought another 2 fuses and installed one, thruster worked perfect out of the water (tried it both ways for a couple of seconds each way).
At this point I assumed whatever was in the tunnel had dislodged on my way from the marina to the ramp. So I put the boat back in the water, toggled the stern thruster on, lasted about 1 second and blew another fuse.
Called my electrician friend for 3rd time and we bypassed the wiring and went directly from the bottom of the fuse to the thruster with jumper cables. Blew yet another fuse after 1 second (that's 4 for those counting).
Conclusion, the thruster motor works fine with no load, but as soon as there is any load it blows a fuse.
I have been it touch with PBH several times during this saga, and they have agreed to send me a new thruster motor under warranty.
Out of interest the thruster motor is warrantied for 2 years but the time to diagnose the problem is not, nor is the removal or installation.
Has anybody else had a problem like this?
Before I install a new thruster motor and several new fuses I'm hoping someone can confirm my diagnosis or let me know what else could be wrong.
Thanks in advance.
BTW - I can also confirm pulling a stern thruster motor is no picnic, but the 2nd time is much easier.

 

[Brian B]

I had a problem two years ago like this and the replacement fuses were aftermarket and had to be cut to fit the posts.
I ordered the proper fuses from Ranger and have not had a problem since. The problem might be that the fuse you are using are not adequate. If that is the case at least you have a spare motor 😀

 

[downey]

That is very true with the fuses, I did have to modify them to fit.
I have ordered 2 fuses to come with the new thruster motor.
Hopefully that will be the answer.
Thanks

 

[downey]

I ordered 2 - 50 amp fuses from PBH (dealer) and he informed me they are 150 amp fuses!
So I will re-install the thruster, put the correct size fuse in from the dealer and hope it all works.
Still a mystery why it quit in the 1st place?
I will post when I get it solved.

 

[downey]

All is well, I was installing the wrong size fuse. Both my electrician friend and myself read them as 50 amp when in fact they are 150 amps. I ordered 2 from PBH and re-installed the thruster with a new fuse and it's back working like new.
When I had the thruster on the boat I could not get the rachet from Side Power to fit, so I had to use a 6mm open end wrench and turn the bit, one sixteenth of a turn at a time (very painful when bent over with your arms stretched as far as you can).
While I had the thruster on the bench I was able to barely get the bit in the screw/bolt, so I ground another 1/8" off the end of the bit and it works very well now, was much easier to re-install the thruster.
So in future if your thruster goes check fuse 1st and buy correct fuse from dealer. Failing that trim a 1/8" off the bit and use the ratchet the 1st time.
Hope these few tips help somebody.

 

[Jake]

Although I have none of your mechanical abilities, the story still sounds like something that would happen to me, especially the part about the fuses. I guess the only question left is why the fuse blew in the first place. Not a problem if it doesn't happen again in the near future. Glad you solved the mystery.

Jake