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2000 Sunsetter LXi whining/roaring noise between 25-28 mph

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Recent encounter between tracking fins, prop, and some angry under water object. A few weeks back while pulling a wake boarder, I hit something under the water and knocked of 2 out of 3 of my tracking fins as well as some pretty good damage to my prop.

I had the prop repaired, ordered two new tracking fins and replaced those as well. Put the boat back on the water and all seems perfect except a constant whining/roaring noise when cruising between 25-28mph. Other than that, the boat runs perfectly smooth with no vibration, and noise is not present from 0-25 mph and disappears again after approximately 28+ mph.

The noise seems to come from the hull and sound increases when we open the ski storage door. Coincidentally, the two front tracking fins that were replaced are right in that area. With all the said, does anyone know if the tracking fins could potentially be causing noise in the water? After replacing the two front fins, you can indeed see that the last/rear fin is slightly bent which must have happened during the under water encounter. I'm wondering if a bent fin or the new fins could be causing some kind of water/air noise at a certain speed.

Please let me know if you have any experience or thoughts on this issue.


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I'd be surprised if it was a tracking fin problem, sounds more like a spinning shaft/prop problem, maybe alignment.

If you wanted to test it, you could get up to about 40mph, kill the motor, and coast back down though the problem mph.

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I could imagine the tracking fins doing this. You could maybe test them easily by wrapping them all into one bunch with a few wraps of duct tape and see if the noise goes away.

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Thank you all for the quick replies, and great suggestions for troubleshooting. I'll definitely give the duck tape a try, as that should give me an immediate idea on whether it's the fin alignment, or if I need to look further. As mentioned, I can definitely see a bend in the 3rd fin, and upon closer inspection, it looks like the 1st/lead fin that was replaced is at a slight angle as well. Thanks again.

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Check to make sure the engine mounts are all OK. Then start looking at the shaft alignment. Start at the coupler, then open up the shaft log. I had a grinding noise once and it turned out that when the mechanic did the 10 hour service and re aligned the engine to the prop shaft he forgot to tighten all the mounts properly. The prop shaft was contacting the inside of the shaft log flange. Your sound description is similar to what we experienced. I figured it out by putting the boat in gear on the trailer at the boat launch. I had the engine cover up and the engine moved all over the place.

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I used to be part owner in a Response that had a couple fins knocked off. We spent extra solid cash getting it repaired by a fantastic glass shop. Everything looks perfect, boat performs as it did before the issue, but there's a resonance / high pitched vibration of the tracking fins at 34-35mph. It's silent below 34, and silent above 35, but sings at 34mph. My guess is the tracking fin and the turbulence created with the tracking fins.

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