vibration and noise at certain speeds

Well I think almost all of the kinks are worked out of the boat, but had her out on the water this weekend and just one last thing is bothering me.

I get a slight vibration when I kick it in gear at idle speed...it's nothing too crazy, but enough for me to notice in the steering wheel. When I speed up, at certain speeds or possibly RPM I get the same vibration accompanied by some noise. Then at other speeds the boat runs perfectly smooth. I did notice that I get a fairly steady flow of water coming in from the prop shaft and was wondering if that could be the culprit? Any ideas or places to start? Is there a bushing or bearing to check where the shaft goes through the hull and how do you look at it?

just had a tranny rebuild and alignment...also had new damper plate installed at that time...are there other common culprits to check? thanks for the help.

harbor marine in everett, wa did all the tranny/alignment work for me...prop looks good...almost feels like something under the boat could have a little play or is a little loose which vibrates at certain RPMs/speeds...the boat saw some salt use before i owned it so not sure if that helped something corrode/rust

thanks for the help...yeah after the $$$ i spent i hope they didn't half ass it, but you never know. wish i could have sent it to eric, but the spline welded itself to the drive plate...not fun. i will check everything from the tranny back to make sure its all tight, and of course crank down that packing nut a little. i'll post results...could my hull just be making noise at certain speeds??? it's been doing this since i have owned the boat, improved slightly after tranny rebuild.

thanks for the pointers Joe....if that rudder wiggles is it time to replace or can it be tightened somehow?

so after spending a couple minutes with the boat in the driveway today, i rotated the shaft to see how it felt. It rotates pretty freely most of the way around, but there is a small spot where it feels just a little tighter. could that be the source of my vibration?

i am assuming not...might be worth a call...they did give me a one year warranty on the tranny so maybe i can WTF them on this one. should be buttery smooth after the money i spent there. add this to the lessons learned book for me.

theumer, Have you seen the pictorial thread Eric did on alignment? It really is pretty basic and only requires some basic tools. (2 9/16" wrenches and a feeler gauge) If I were you, I'd unbolt the shaft coupling halves at the trans and check the alignment myself. When checking, you can check for a bent shaft forward of the strut at the same time. It takes about 30 extra seconds!!! I wouldn't trust the marina.

Mike at harbor marine is good with tranny's, but i dont know who did the install, im sure you took out a second mortgage after you left there, but, whats done is done and he may of eyeballed the alignment and thought it was good. i would go back through and check everything
i just finished a tow boat after 3 rebuilds and mine was the fourth, the first thing i did was check the alignment and it was out .021 and the mounts were froze and never touched and i had the customer take the mount to the guy's shop and his kid said you'll never break that free......to end the story my customer asked him i thought i paid you to align it....we did get it freed up and i got the alignment dead on and no more overheat on the trans.
This guy should of never had to go through this, his boat was down 4 weeks and probably lost 20 or 30 tows at 400.00 to 500.00 per tow

I used a crowbar to shove the engine side-to-side - didn't take much - it was obvious how much it moved but a pencil mark would be a good idea so you can go back to your starting point if need be.

Good morning to you as well Greg!! No cam shaft yet?

yes second mortgage is unfortunately history now. ..mike was awesome and knowledgeable and did a great job, but he was only the rebuild guy. the reinstall and other maintenance just went through their service department not the tranny shop.

eric i have read your post on alignment which is awesome by the way. i did run the boat for about four hours with no overheat issues, and the tranny wasn't too hot to touch...i checked for play and there wasn't anything near the cutlass bearing.

the only thing i noticed was a little play where the (excuse my terminology) coupling bolts up to the shaft??? finally, how can you tell the difference between a bent shaft and misalignment? will it be obvious as soon as i unbolt the drive shaft?

i'll have the crowbar on standby to move the engine

thanks eric i'll be sure to keep my distance from that prop...so i guess i will hope for a slight misalignment which would be the economical fix out of the two.

good point...don't want to diagnose one problem and cause another.

i forgot to mention not to wear a scarf while watching the shaft turn too....
some common sense is requried and i have a tendency to forget that everyone doesnt have common sense
side note: I use wd 40 when doing this method and i dont leave the boat in gear for extended periods, i will have someone in the boat and will tell them to snap it in gear, look for a wobble and thats it. Pete this method hasnt failed me yet, if its bent you will see it, alot of times it will run true before the cutlass and wobble after the cutlass
liabilty clause: dont try this at home under no circumstance