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View Full Version : Some shuddering when in reverse


mcskier
04-18-2012, 11:18 AM
Anyone got any ideas here? 08 197TT, only 350 hours on her...

Boat develops a shudder when in reverse. Not bad, but starting to really bother me. No issues at all when in forward at any speed so I would think that rules out any bent running gear. New prop. Fluid is fresh and has never been dirty or low.

davidstan
04-18-2012, 02:04 PM
Every so often mine will shudder but only for at the most 2 seconds. No other issues.

Double D
04-18-2012, 03:04 PM
Isn't that called cavitation?? :rolleyes: :D

mcskier
04-18-2012, 04:12 PM
Isn't that called cavitation?? :rolleyes: :D

I suppose it could be cavitation, but I guess I don't fully understand the phenomena. I'm mean I know that cavitation is basically when the prop isn't grabbing enough water to propel the boat; air pocket forms around the prop...

I can understand it high rpms, but you typically only use reverse for very low speed maneuvers/corrections or backing away from a boat launch, etc. I wouldn't think there would be much opportunity for cavitation in those situations. It's certainly not like I'm driving around in reverse all day long!:rolleyes:

AussieMC
04-18-2012, 07:05 PM
Just a small suggestion, I drove a 2011 tt at a tournament recently, and it made a shudder as I put it in reverse. we liofted the boat at the end of the day and found that the prop nut had worked it way loose and the prop would "shudder" its way down the shaft in reverse. Tightened the nut, all good.

mcskier
04-20-2012, 11:55 AM
So the dealer had my boat yesterday and checked over the boat both in and out of the water. One of the first things they noticed was that when out of the water, the prop spun too freely. This makes them think the strut bushing needs to be replaced. They also noticed too much water coming in via the "dripless" shaft seal. Gonna replace both parts and see if that solves the issue. Both are OJ parts...same guys who make the prop.

At 355 hours, should I have expected to be replacing these parts already? Or does this sound like an anomaly?

rgardjr1
04-20-2012, 01:14 PM
At 355 hours, should I have expected to be replacing these parts already? Or does this sound like an anomaly?

Probably an anomaly, but I'm getting new strut bushings put in today after 275 hours. My rear bushing had spun out. Explanation that I was given was that something may have gotten in between shaft and the bushing (fishing line, sand, ect.) that caused it to spin out. I'm glad that I noticed it when I did sounds like it will be a relatively quick and easy fix.

Table Rocker
04-20-2012, 01:41 PM
If you are reversing hard enough, you can actually pull air down from the stern (since the prop is so close) resulting in cavitation.

When I worked on towboats, they would shudder violently in reverse from this same situation.

mcskier
04-20-2012, 05:14 PM
If you are reversing hard enough, you can actually pull air down from the stern (since the prop is so close) resulting in cavitation.

When I worked on towboats, they would shudder violently in reverse from this same situation.

Interesting... I'm pretty certain this issue is not cavitation given that we've found a likely culprit in the strut bushing. I've driven dozens of 190/197s and this is the only one that I've known to have this kind of vibration. Like I said before, reverse is only for docking and maneuvering in tight quarters. I don't think I've ever put a boat in hard reverse.