Loose rudder

[russm313]

I have recently replaced the rudder on my 1979 skitique. The problem is I can't get it to stay tight. I will get it real snug at home, and can't even budge it with my hands, but as soon as I put it in the water and get up some speed, the boat feels like its about to fall apart from the vibrations. So, I take it out of the water and sure enough, the rudder is loose. I can jiggle it by hand. Can any one help me out on this? Thanks in advance,<br />Russ

 

[dick]

Re: Loose rudder

You may have 2 problems.You say as soon as you are up to speed the boat is vibrating? If so I bet you have a damaged prop or bent shaft. have you hit anything recently ? Why did you replace the rudder?

 

[russm313]

Re: Loose rudder

Yes, I hit a log and it broke my rudder off clean with the bottom of the boat. There is a small bend in the prop but it is very slight. It also bent the strut that supports the shaft, but I have had that straightened since then. The reason I think it is the rudder, is because when I first replaced it, and took it out, it would vibrate so bad that I couldn't get up over 20mph. So, I brought it home, tightened it down real good and took it out for another test drive. This time is was MUCH better. I could easily get to WOT but the vibration made my feet go numb. So, when I pulled the boat out of the water and checked the rudder, it was loose again, but not NEARLY as loose as it was on the first test. So, I am thinking if I can get it to stay tight, then the vibration might stop. Even if it doesn't, I'll be able to eliminate the rudder and move on the next suspect. Thanks for all help,<br />Russ

 

[TwoBallScrewBall]

Re: Loose rudder

Sounds like the bent prop is generating vibration that is loosening the rudder. Even a slight bend turns into quite an imbalance once that thing starts spinning. Get the prop repaired/replaced and try it again. Also double check the driveline since you hit something that hard, you never know.

 

[mabbott]

Re: Loose rudder

I would guess that the shaft is bent if the strut was bent. Almost any amount of run out on the shaft will cause vibration. That and the fact that the prop is bent will do it also.

 

[russm313]

Re: Loose rudder

Ok, sounds good so far. I'll get that prop fixed, then tighten the rudder back up and try it again. One more question. <br /><br />Is there an easy way to tell if the drive shaft is bent? Can I take it off and roll it on the ground to see if it wobbles?<br /><br />Thanks,<br />Russ

 

[CCrew]

Re: Loose rudder

"Can I take it off and roll it on the ground to see if it wobbles?"<br /><br />Only if the ground is perfectly flat! <br /><br />In a machine shop I'd either have it on a surface plate in V-blocks with a dial indicator, or chucked in a lathe with a live center and an indicator. If you can duplicate that precision on your floor, then I'd say it's checked! (grin)<br /><br />Seriously. Checking and/or straightening is a job for a shop with the proper tools. <br />-Roger

 

[snapperbait]

Re: Loose rudder

Russ.. I'm with the others here... Problem ain't the rudder.... Get the prop straightend out, check or have checked the run out on the shaft and then align the whole mess with your feeler gauge to within .002-.003 thousanths at the shaft/transmission coupling...