Preventing thruster shear pin failure

[scross]

I believe the owners of Ranger Tugs fall into two groups - those who have had a thruster shear pin failure and those who will have a shear pin failure.

Right now I’m in the latter group and want to keep it that way for as long as possible.
What insights for those who have had a thruster shear pin failure have?

I’ve heard two recommendations so far:
1. Always, always be sure your thruster is underwater before engaging it. That means to not engage the thruster in wavy conditions or when underway.
2. Wait at least 2 seconds in “neutral” between changing directions with the thruster control.

Other tips?

 

[stwendl]

I think I have written about this before. In my opinion, the instant force the thruster motor is throwing against the mechanical device attached to its shaft is so high that I am wondering why those pins do not break more often. To prevent shearlin failure an electronic start control should be added in that not only ramps up slowly but also can detect mechanical obstructions by unusual unexpected high current and then turn off power before such shear pin breaks. Thus reducing the shear pin to a last resort fail safe component and making shear pin replacements a part of the past.
I am sure such electronic devices are already available.

 

[Red Raven]

Hi Al,

The recommendations are good though waiting 2 seconds is probably overconservative. As long as you don’t go directly from one direction to the other and hear them stop in between I think it is enough. The only thing I would add is not to use them if there is junk in the water.

Ultimately though I think they will eventually fail with the brass pin. My pin did not have clean shear look to it. Lots of bits and brass dust. I think it was slowly wearing through. It is important to become familiar with the change out process and have the correct tools handy. Per a post on another thread it looks like Imtra is now only offering a stainless pin replacement. This should go a long way towards reducing the breakage potential.

Curt

 

[Irish Mist]

Although lately I have not been boating a lot, in the past we would be out and back from our marina a few times every week with lots of docking and rafting up beside other boats. Lots and lots of thruster use. My boat is a 2011 and my only pin failure on my front thruster was a result of me sucking up my anchor rode... Needed prop , pin and a gear leg...The pin showed no signs of wear just a clean break. But other then that it has taken my use and abuse with out any issues for years..Having had issues with the rear thruster I use the front thruster a lot more then the rear.. Just positioning the direction of travel and using the engine. The rear thruster has had an ongoing issue that I am hoping I have resolved finally so it has seen a lot of new pins, and of course it is a bear to access..
I am really surprised at how long the front pin has lasted. I do not baby it, but I do use it in bursts and let the boat drift.. unless currents or winds are strong.

 

[captstu]

When my boat’s rear thruster failed, I paid 4 labor hours to replace the pin.

2 weeks later I struggled to repair it again when it failed for apparent reason. Took me about 8 hours- the mechanic and local side power shop refused to ever step foot on a Ranger again - tight access.

Second time I inspected the leg as the mechanic should have done.

So, new leg - not much extra work or money.

I concluded the pin is a worthless part, the leg fails anyway and the fuse. (That I replaced with a 100Amp Blue Sky circuit breaker) adequately protects the motor. So I replaced the pin with a stainless pin.




Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[Sine Wave]

I lost my bow Thruster due to pin failure. When I checked I found lots of brass shavings where the pin was located. It was at that time I realized that I had recently had the bottom paint replaced and fortunately the boat was out of the water. I then checked if the prop would turn. When it did not turn easily I assumed that I might have a bad gear leg. I almost replaced it ($500.00) but looked further and found that the new bottom paint was keeping the prop from turning easy.
A little sand paper and elbow grease and I fixed that problem. Works fine now. If you have a bottom paint job, check your Thrusters to make sure they haven't been painted to the tube.

Sine Wave
R-27

 

[Brian B]

I lost my bow Thruster due to pin failure. When I checked I found lots of brass shavings where the pin was located. It was at that time I realized that I had recently had the bottom paint replaced and fortunately the boat was out of the water. I then checked if the prop would turn. When it did not turn easily I assumed that I might have a bad gear leg. I almost replaced it ($500.00) but looked further and found that the new bottom paint was keeping the prop from turning easy.
A little sand paper and elbow grease and I fixed that problem. Works fine now. If you have a bottom paint job, check your Thrusters to make sure they haven't been painted to the tube.

Sine Wave
R-27
This seems to be a common issue when yard workers slop the paint on. I remove the props and paint them when the bottom is being painted. I also tape off the threaded shaft and zinc.

 

[captstu]

While you’re checking take a look at your water in the screens. When I had my boats bottom painted last, they painted the screens. I had no idea that was the problem and spent $10,000 looking for colon problems that the pants screens cost.