Help with new shaft/coupling/alignment

[JC]

Finally planning to put boat in the water after 2 months!!!!

Replaced broken shaft with brand new aquamet 22 1.5 inch.

After I had put the coupling on and bolted to transmission I went back to turn the prop and I noticed there was a bad misalignment immediately. I could tell where the shaft went in to the shaft log that the shaft was going un and down!!! Whats wrong!!! So i went back to the coupling and unbolted and rebolted trying to apply equal pressure on all bolts but I can still see some misalignment. What is the correct way of doing this??

Thanks for your help. I need to put the boat in the water ASAP.

Thanks!!!

JC

[Bruce]

First thing you want to make sure is that the shaft is true into the coupling and the face of the coupling is true.

If the coupling was anything but a very snug fit on the shaft, look at that.

If the coupling is cocked on the shaft it will produce an eliptical path.

So will a bent shaft.

Don't assume cause everything is new that it is alright.

If that checks alright, then bolt coupling/shaft to gear and bring the coupling faces within 15 thousands using feeler stock or guage.

Check between bolts all the way around. It should be the same. If not then adjust mounts to bring to a maximum of 3 to 5 thousands. Closer or all the same is better.

If you have to adjust mounts make sure you don't raise or lower the engine and the shaft hits the log. If you have to do this then look at the strut being out of whack.

[scot]

I noticed there was a bad misalignment

How did you "notice"...was this visual at the shaft log, or by hand at the prop. It is posible to have the trans flange and the rear strut aligned (read: no vibration, runs fine) and still have the shaft penetrationing the log in a wierd spot (off center)

Think of the strut and the trans flange as the main event and the shaft log as a semi-flexible seal to keep the water out. The "seal" does need to be in the ball park, with no shaft rubbing on the brass log.

[JC]

Thanks for your inputs. That helps alot. When I put the shaft in the fisrt time the shaft was too long so I had to cut a piece to be withing the 1.5 inch tolerance between strut and prop. Can this have something to do?? The cut was not perfectly straight. But what aligns doupling with the transmission is the coupling not the shaft so??? I thought this would be no problem??

Could not make it to the boat today but have been providing instructions to a guy there. He said he has got it to a point where there is no noticeable eliptical movement (to the eye) but he thinks there is still about a 1mm "eliptical" I think he measured with a straight edge. One of the bolts got striped so he can tighten that one completely. Do you think that can affect. These are some tight tolerances!!!

What should I do. Try and fix out of water or put into water and finish alignment there.

JC

[Rawleigh]

In water after a couple of days of settling in!!

[Bruce]

JC,
I understand your location. But shaft aglinment is critcal. You need to try and find someone who knows whats going on if possible.

[JC]

I understandt. I will not risk the boat or crew if things arent done right. I think I know where the problem was. Yesterday I asked my captain to take the coupling off and check the face to make sure it was true (straight) He put the face over a piece of glass and there two spots around the "step" where a groove mates with the transmission that were not level. The problem was that one of our helpers who I already fussed at had been slaming the coupling with a sledge hammer to get it onto the shaft. The fit into the shaft was very tight. I told hime next time put a block of wood in front.

So what he did is he sanded those "burs" or bumps out and put it back on. He said the faces where flush (well mated) to each other after doing that. He could not observe any more "eliptical" movement on the shaft. The only problem he had is one of the bolts got striped so today we are trying to locate replacement to get allo done. My plan was to put boat in the water today idle it to mooring and let it sit for a couple days and the trial to see if there is any vibration. If there is vibration will take a llok at engine alignment etc... and fix.

It is very hard having a boat here. I am not a mechanic but I have had to learn how to fix some things myself. I read alot and try think/logic/solve things alot. I have always had a mechanical mind but what I lack is experience. I get the experience as I learn new stuff on the boat. I have tried to locate quialified personell here but I just cant find anyone who know boats well. The only guy is the guy who owns the lift who has been a sailor all his lif (from Canada) but he is out of the country.

The other people who I have thought could have some knowledge are the shrimping fleet of the country. The only difference s that tolerances on those boats must be les strick thatn on a faster rev engine.

Anybody interested in coming to El Salvador for a week. We can trade good fishing in exchange for some good mechanical knowledge!!!

JC

[JC]

Heres a couple of pics.....

Juan our helper with a stub that was cut from Shaft



Boat Before





Boat After