Thruster Sound has Changed

[Dog Islander]

Lately when I engage my rear thruster it has a different sound when the stern of the boat is pushed to starboard. The best I can describe the sound is that of brief cavitation or the spinning of the shaft prior to the prop catching and only in that one direction and only on the start of the thruster each time I go in that direction. It does not happen when pushing to port. It sounds normal after the initial noise clears, maybe lasting a second or less, but it seems like an eternity knowing what I may be faced with in the far reaches of the stern of the vessel. There seems to be some air trapped in there, or maybe some play in the shaft and prop. I can't see anything from the dock and the water temperature in the Salish Sea is not agreeable with my nervous system to go swimming. I have a diver due to change the zincs within the next month and I'll likely have him inspect the external parts. Has anyone else experienced this sort of sound or have ideas as to what it might be?

 

[bbrh842]

Something in the tunnel, like a piece of string, or monofilament.

 

[baz]

Before getting too engaged I'd wait for the diver's examination. That may reveal to you a complete understanding.

If the diver is agreeable you could ask him/her to be in the water looking at the stern thruster from a safe distance while you operate it in the fashion you've described that causes your concern.

 

[trailertrawlerkismet]

I agree with Barry with the added caveat that the problem may be because a barnacle build up on the one side, keeping the propeller from operating properly and therefore making the new noise.....it has happened before on my thruster.

 

[Auklet]

Sounds familiar. Check your deflectors. One of ours broke off. Instead of bringing water from below, it brought in a column of air from above. This caused a brief cavitation until the air cleared. Common problem on early models. Ranger now makes a much stronger deflector.

 

[walldog]

We had two gear boxes replaced on our 27. The first one was my fault, I caught a line from the dinghy in it. The gear failed, the shear pin did not. Later it started making noise as you described and sometime later it failed again. This was in the first year, no more issues after that. The eggs are great!!

 

[Dog Islander]

I visited Nudibranch this afternoon and took a look between the stern and swim step. With the aid of a flashlight I could clearly see the asymmetry of the stern thruster. The starboard cowling was completely missing from the tunnel. It looks like either a clean break or whatever was attaching it to the tunnel gave way. Cary, it sounded as though this was a Ranger Tug manufactured part. I didn't see these tunnel extensions listed on the Side Power website. I have a message in to Andrew to see what my next step is. Thanks for all the suggestions. It could be even more involved than a missing cowling. Maybe an object was caught in there and caused the piece to depart from my company...

 

[Auklet]

The factory flanges on the deflector were weak. Ranger made up some new ones that were much stronger. Check with Ranger parts, they should have them. The flanges are not drilled, so save as much of the old ones as you can for a guide. I was lucky, this happened to Auklet just before annual haul out. I just replaced the broken one. Probably smarter to replace both. --- Cary

 

[baz]

Please post back with what Andrew advises.... thanks. 🙂

 

[Dog Islander]

Cary you are spot on. Barry, Andrew advised I call Richard and knowing from experience I did as Andrew suggested. Richard has a shroud in stock, a Ranger fabricated fiberglass part to replace the stock plastic part. I expect to see it within a week or so and I'll post what I find when it's been hauled. I'll probably go ahead and bottom paint if it looks anywhere like it could use it, do the zincs and replace any corroded hardware that shows. Now to find a shop in Anacortes that has an opening in their schedule.

 

[Dog Islander]

Here is the scoop on the thruster. Richard at the factory sent out replacements within a day or two. The thruster scoop was missing on the right side. The screws completely corroded away. The port side were clearly corroded but intact with the scoop. I replaced both and had the bottom painted with two coats of Seahawk Af33. Looks sharp. While high and dry, I had the thruster and propnut zinc changed out. I found the prop but in decent shape (>70%) but was only hand tight. That suprised me because I just came back from a long weekend trip. Why it didn't spin off baffles me. Thruster works great! Thanks to Richard at Ranger Tugs for the prompt service.