Drive line alignment

[Backdraft]

I have a 28' single screw cruiser. I've had the prop shaft and prop off for repairs, as it was damaged when I bought the boat. I put it all back together and have a vibration right at a comforatable cruising speed. Lower speed is fine, and faster is okay. The only thing I haven't done in a profession manner is align the shaft and strut. I'm thinking this could be the culprit. The boat is in a remote part of Oklahoma with few boat yards that could help. Is there a way I can check the alignment of the shaft and strut myself? Will this vibration damage anything else? Backdraft...

 

[Beckytek]

You don't say what you did in the way of repairs. Did you have a bent shaft? bent prop? Were they repaired at a prop shop to check for fairness and balance? There are many reasons for vibration and every part off your running gear has to be correct to start with. You may not have put the prop on correctly, or your shaft flange may be out of alignment with the engine flange. If you give us more information maybe we could help you more. Ron

 

[Brian Degulis]

Yes you can check the alignment it's pretty simple. Do a search here there have been lot's of good posts on it.


Brian

 

[Backdraft]

You don't say what you did in the way of repairs. Did you have a bent shaft? bent prop? Were they repaired at a prop shop to check for fairness and balance? There are many reasons for vibration and every part off your running gear has to be correct to start with. You may not have put the prop on correctly, or your shaft flange may be out of alignment with the engine flange. If you give us more information maybe we could help you more. Ron

The Shaft, strut and prop were damaged. I had the prop repaired at a reputable prop shop. I had the shaft and strut straightened at a reputable machine shop. If my memory serves me correct the machinest told me he straightened the shaft to within .002". Whatever it was, he said it was a closer tolerance than factory shafts. I was wondering about the flange alignment. I don't know how to check that or change it. I have another inboard runabout I've kinda been using to check for things, because I know it is set up right, but I can't tell that there is any adjustment on those flanges. I do know the cruiser has more slop in the cutlass bearing than the runabout. I've run the engine of the cruiser out of the water and looking at the end of the shaft, it appears true. I can detect no wobble there. Any advice would be appreciated. --Bill

 

[Boatsb]

Don't run the engine on the hard or the cutlass bearings will melt. They need water to cool them.

If the boat is in the water with the shaft installed it is too late to have the shaft and flange checked. I would have brought the flange to the shop and had them do a check. They usually do not bend but if it is not installed on the shaft right it may be off. the key is to get the key smooth and not to tight that the fit is on the shaft not riding the key.

Once in the water you will need to re align the engine no matter how well the struts were straightened. It may just be a few thousandths but the face of the coupling is so far back from the struts that the smallest deviation is magnified and can be an issue. Its a simple process but a bit time consuming and sometimes made difficult because you are moving a heavy engine.

 

[Backdraft]

Thanks for everyones advice. I have found some good info on this site about engine and shaft alignment, and cutlass bearings. I have not found any set screws in the cutlass bearing. Are they normally visible on the exterior of the strut? --bill

 

[Beckytek]

The screws are hard to see. You'll have to clean the strut very good to find them. A little bottom paint will completely cover them. Ron

 

[34Hatt]

On my strut someone must have use a brass screws and then cut it flush and sanded it smooth

What a PITA I didn't find them until I took the first one out in three piece's. Then the other I sanded all the paint off and found the little circle then drilled them out!!