peterkvs
Active Member
A couple months ago I posted that I had hit a submerged object and bent something. The post was http://clubsearay.com/showthread.php/64754-Hit-a-submerged-object-bad-vidration-now-what-to-do?highlight= Since then I have been working on the boat and finally gotten the problem fixed. Here is the story...
I pulled the boat out of the water and removed both props and both shafts. I noted that the shaft zinc anode on the starboard shaft was jammed into the strut and was still tight on the shaft. It was not like that when we put the boat in the water last fall. The props did not look that bad and really only one blade looked tweaked a bit. I sent both props off to get scanned and straightened. I took the prop shafts to a local machine shop and cleaned all the junk off them in a lathe with emery cloth and then set them up in precision v blocks and checked the run out with a dial indicator. One shaft was fine and had a runout of about 1-2 thousandths. The other propshaft had a runout of .040" in the last 18" of the propshaft on the prop end. This was the propshaft that had the anode jammed into the strut. So something hit that shaft hard. I tried to have the machine shop straighten the shaft and the best they could do was about .007" which was not good enough since the spec is less than .002" I called around and eventually lucked into a company that had made the exact shaft I needed before for Sea Ray and they actually had the drawings for the shaft. So, I contracted them to build a new shaft, which they did in a couple of days. I also sent them my coupling so that they could verify the fit on the taper and check that the coupling face was perpendicular to the shaft and take a light cut on the face to make it so if it wasn't.
The props came back along with a scan report which showed that one blade on each prop was way out of pitch compared to the others, and so they must have hit something. I noted that one shaft had a sure seal and the other had the original strong seal, which was worn. I bought a new sure seal for the new shaft and a new lip seal for the other shaft. While I was waiting for the parts to arrive I was thinking about how I could check the alignment of the engines to the shaft log and strut. Frank sent me some ideas and a link to a shaft installation that Masterfab had done which gave me an idea. I had a tapered cone made that was 6 inches long that had a hole in the center the exact size of the propshaft. The taper on the cone was 3.25" on one end and 2.5" on the other, the ID of the shaft log was 3".
I installed the shaft without the sureseal and in its place I put the tapered cone. I then could slide the cone down the shaft and into the shaft log which perfectly centered the shaft in the log.
Now that the shaft was supported at the prop end by the cutless bearing and at the shaft log by the cone, I could install the coupling onto the shaft and align the engines. The starboard engine was very close, but the port engine needed to be moved sideways about 3/16th of an inch!
So with the shaft held centered I aligned both engines left and right and up and down to withing a couple of thousandths. Then I aligned the gap in the coupling halves to one thousandth.
The next day I installed the sureseals, the shafts and props and got it all buttoned up. I also took the time to add cross over cooling between the sureseals so that if I had to ever run on one engine I wouldn't have to worry about tying the prop in place to keep the seal from overheating.
The following day we splashed the boat and I moved it back to my marina. The boat was very smooth with no signs of vibration. After a week I checked the alignment and the starboard coupling was within one thousandth and the port coupling was within two thousandth. I mucked around with the port side and could only get it within .0015", but that is well withing the .004" spec. I took the boat for a spin and was very surpirsed at how smooth the boat was and the noticable lack of vibration at all speeds. I was also surprised that the boat picked up a whole knot of speed. Previously at 2400 rpm it would run 23 kts and at 2800 rpm it would run 28 kts. Now it runs 24 kts at 2400 and 29+ kts at 2800.
All in all it was a pretty easy and straight forward job and the results were excellent. Now I just have to get over the paranoia of hitting something else in the water.
Pete
I pulled the boat out of the water and removed both props and both shafts. I noted that the shaft zinc anode on the starboard shaft was jammed into the strut and was still tight on the shaft. It was not like that when we put the boat in the water last fall. The props did not look that bad and really only one blade looked tweaked a bit. I sent both props off to get scanned and straightened. I took the prop shafts to a local machine shop and cleaned all the junk off them in a lathe with emery cloth and then set them up in precision v blocks and checked the run out with a dial indicator. One shaft was fine and had a runout of about 1-2 thousandths. The other propshaft had a runout of .040" in the last 18" of the propshaft on the prop end. This was the propshaft that had the anode jammed into the strut. So something hit that shaft hard. I tried to have the machine shop straighten the shaft and the best they could do was about .007" which was not good enough since the spec is less than .002" I called around and eventually lucked into a company that had made the exact shaft I needed before for Sea Ray and they actually had the drawings for the shaft. So, I contracted them to build a new shaft, which they did in a couple of days. I also sent them my coupling so that they could verify the fit on the taper and check that the coupling face was perpendicular to the shaft and take a light cut on the face to make it so if it wasn't.
The props came back along with a scan report which showed that one blade on each prop was way out of pitch compared to the others, and so they must have hit something. I noted that one shaft had a sure seal and the other had the original strong seal, which was worn. I bought a new sure seal for the new shaft and a new lip seal for the other shaft. While I was waiting for the parts to arrive I was thinking about how I could check the alignment of the engines to the shaft log and strut. Frank sent me some ideas and a link to a shaft installation that Masterfab had done which gave me an idea. I had a tapered cone made that was 6 inches long that had a hole in the center the exact size of the propshaft. The taper on the cone was 3.25" on one end and 2.5" on the other, the ID of the shaft log was 3".
I installed the shaft without the sureseal and in its place I put the tapered cone. I then could slide the cone down the shaft and into the shaft log which perfectly centered the shaft in the log.
Now that the shaft was supported at the prop end by the cutless bearing and at the shaft log by the cone, I could install the coupling onto the shaft and align the engines. The starboard engine was very close, but the port engine needed to be moved sideways about 3/16th of an inch!
So with the shaft held centered I aligned both engines left and right and up and down to withing a couple of thousandths. Then I aligned the gap in the coupling halves to one thousandth.
The next day I installed the sureseals, the shafts and props and got it all buttoned up. I also took the time to add cross over cooling between the sureseals so that if I had to ever run on one engine I wouldn't have to worry about tying the prop in place to keep the seal from overheating.
The following day we splashed the boat and I moved it back to my marina. The boat was very smooth with no signs of vibration. After a week I checked the alignment and the starboard coupling was within one thousandth and the port coupling was within two thousandth. I mucked around with the port side and could only get it within .0015", but that is well withing the .004" spec. I took the boat for a spin and was very surpirsed at how smooth the boat was and the noticable lack of vibration at all speeds. I was also surprised that the boat picked up a whole knot of speed. Previously at 2400 rpm it would run 23 kts and at 2800 rpm it would run 28 kts. Now it runs 24 kts at 2400 and 29+ kts at 2800.
All in all it was a pretty easy and straight forward job and the results were excellent. Now I just have to get over the paranoia of hitting something else in the water.
Pete
