Prop shaft

[PM in TO]

1) On my 2005 310 the diagram (see attachment) in the manual for the stuffing box shows the packing as 3/16" and three rings yet when I removed the old one it looks like ¼" does anyone have an updated drawing?
2) Check the next two pictures (shaft going through the hull) in the manual they direct you to perform the prop shaft line up/couplings to be performed in the water to allow of flex in the hull, and I have checked this a couple of times and appears to be good. However in the drawing that shows the stuffing box details it recommends the shaft be centered in the fiberglass tube. In the attached pictures you can see that the shaft appears to be closer to the bottom of the opening then the top although it is not touching as best I can tell. Which is correct? And do I need to remove that reinforced rubber hose that connects the stuffing box to the fiberglass tube to see if the shaft is centered? The reason for my asking,, ever since I purchased the boat in 2010 when the boat is sitting at the dock idling in neutral there is especially on the port side a sharp tapping noise, that to me does not sounds right. I have checked and double checked the idle which is set to 1100 rpm as I know this can be somewhat related. My concern is that some where there is a hole being knocked in the hull and I am trying to prevent this. Any ideas welcome

BR Paul

 

[Donnybrook]

It is my understanding that the majority of Catalinas with 1 in shaft take 3/16, but there are a few that left the factory that did have 1/4 in stuffing boxes. If 1/4 will go in the nut without forcing it, then you have the 1/4.
I would definitely raise the engine and get the prop shaft centered. Does not have to be perfect, but certainly better that what you have. I have never noticed any flexing or change in engine alignment between the hard and in the water, at least on my C27.
Now for the bad news, and I hope I am wrong. Your noise could be the damper plate going out. Very common on the XPB engine, if you have one. Do a search here on "damper plate" and C310. Good luck.

 

[PM in TO]

Thanks for your input, regarding your comment about the damper plate, the odd thing is the noise has been the same since I got the boat, and at that point it only had 98 hours, now I have 500 +

 

[JK_Boston_Catalina310]

Yup, I would pull apart the transmission and check the damper plate.

 

[peter_ms]

Thanks for your input, regarding your comment about the damper plate, the odd thing is the noise has been the same since I got the boat, and at that point it only had 98 hours, now I have 500 +

Your damper plate is probably worn; I just replaced mine as part of having to rebuild the transmission... HOWEVER... Judging from those pictures, your alignment is seriously off; not unusual out of the factory. I had a similar issue and had the knocking/rapping/thrumming at various speeds.
If you are cantering the shaft in the shaft log (packing tube) that's not correct. It should be centred in the stern tube itself.
I noticed circumferential scratches on my shaft do I know it was touching. Raised mine (new motor mounts too) and the knocking is gone.

Raise the engine overall, realign and you will likely lose your knocking. The damper plate rattle is an issue at idle; not underway. Given the crappy track record of this engine's damper plate and transmission, you will be replacing one or the other sooner than later.

I am in Oakville; where are you moored?

Peter
C310 #147
OYS

 

[rpwillia]

Motor mounts

I had a pretty pronounced tap tap tap when in idle and especially if I was standing on the dock next to the boat. At that point I had replaced the Cutless bearing, damper plate and done a shaft alignment. Finally broke down and replaced the engine mounts and that solved the problem as well as reducing noise by about 8db in the cabin and cockpit. Since I could not find OEM mounts I went with some ones from a guy in Georgia that we 1/3 the cost and really nice, but needed to make adapter plates as all the new mounts are 4" on center as opposed to 5" on center with the new ones. Something to consider.