Port shaft noise. Let me know your thoughts regarding it.

[Jeremygavin]

Boat is a 2011 520DB with QSM11s and 2 1/2" shafts. I did a shake down run yesterday as it went back in the water last week and I still have a harmonic sound on the port shaft from around 700-1300rpms. The boat did not make this noise at sea trial last Oct when I bought the boat. I first heard the sound when I was leaving Port Washington NY to bring the boat back to MA after purchase and I traced it down to coming from the port strut/prop area. In person at the survey and in his report surveyor had said the cutlass bearing looked good visually and had not play in the port side with very little play in the starboard side. He did note that the struts had looked like they had been re-bedded at some point. I spoke with the surveyor about the issue I got back to MA and he had said he thought it might be prop sing. I thought I was going to solve the issue when I had the props off this winter to have them tuned and little pitch taken out of them it would take care of the noise but it hasn’t.

Here is the like to a video I took of the noise last fall.

https://www.dropbox.com/s/q67zhtyo7zeiv07/IMG_2023.MOV?dl=0

It only makes the noise in fwd. between around 700-1200rpms, it does not do it in reverse. I have no vibration at all at any time. I went back down in the bilge yesterday to make sure the noise is not coming from transmission area but is defiantly coming from the strut area. So it must be an issue with the cutlass bearing. The issue is the yard can’t pull me back out of the water till June do to all the spring commissioning they are doing currently.

My question for everyone is do you think it is OK to run the boat for a month the way it is? I don’t want to do more damage but the boat is in RI for the winter and I need to get it back to MA and I would like to not lose a month while waiting for them to have time in June to get it back out of the water and look at it.

Also, what do you think could cause the cutlass bearing to whine like this? Could it be out of alignment? When I was working on it this spring I can turn the port prop by hand easily and hear no noises in the cutlass bearing when turning it by hand.

Thanks for your time.

 

[sbw1]

Sounds like prop sing and most likely related to tuning the props. Irritating but not harmful.

 

[Jeremygavin]

View attachment 68867 Sounds like prop sing and most likely related to tuning the props. Irritating but not harmful.

That’s what the theory was last fall and this winter I had the props tuned and some pitch taken out of them. I showed him the video and he said the also thought it was prop sing and they put “anti-sing” edges on them or something along those lines. It is a reputable shop that many marinas use in NE so I assume they know what they are doing.

 

[sbw1]

It is caused by the trailing edges of the offending prop not having flat edges. Nibral props may be more prone, although I may be wrong about that. Fix is to file edges flat by someone who knows proper orientation of the edge.

 

[TNT8808]

Boat is a 2011 520DB with QSM11s and 2 1/2" shafts. I did a shake down run yesterday as it went back in the water last week and I still have a harmonic sound on the port shaft from around 700-1300rpms. The boat did not make this noise at sea trial last Oct when I bought the boat. I first heard the sound when I was leaving Port Washington NY to bring the boat back to MA after purchase and I traced it down to coming from the port strut/prop area. In person at the survey and in his report surveyor had said the cutlass bearing looked good visually and had not play in the port side with very little play in the starboard side. He did note that the struts had looked like they had been re-bedded at some point. I spoke with the surveyor about the issue I got back to MA and he had said he thought it might be prop sing. I thought I was going to solve the issue when I had the props off this winter to have them tuned and little pitch taken out of them it would take care of the noise but it hasn’t.

Here is the like to a video I took of the noise last fall.

https://www.dropbox.com/s/q67zhtyo7zeiv07/IMG_2023.MOV?dl=0

It only makes the noise in fwd. between around 700-1200rpms, it does not do it in reverse. I have no vibration at all at any time. I went back down in the bilge yesterday to make sure the noise is not coming from transmission area but is defiantly coming from the strut area. So it must be an issue with the cutlass bearing. The issue is the yard can’t pull me back out of the water till June do to all the spring commissioning they are doing currently.

My question for everyone is do you think it is OK to run the boat for a month the way it is? I don’t want to do more damage but the boat is in RI for the winter and I need to get it back to MA and I would like to not lose a month while waiting for them to have time in June to get it back out of the water and look at it.

Also, what do you think could cause the cutlass bearing to whine like this? Could it be out of alignment? When I was working on it this spring I can turn the port prop by hand easily and hear no noises in the cutlass bearing when turning it by hand.

Thanks for your time.

I can't answer your question, but can say I had a similar albeit slightly different sound from the port side in my 410DA a few years ago, and like you after prop reconditioning, etc it was still there. I had one older (more experienced) gentleman say to check the alignment in the coupler between engine and transmission, and even though everyone in the service department said there's no way that could possibly be the problem when they finally went down and checked it was out .060" Once they aligned it the noise disappeared.

-Tom

 

[sbw1]

I can't answer your question, but can say I had a similar albeit slightly different sound from the port side in my 410DA a few years ago, and like you after prop reconditioning, etc it was still there. I had one older (more experienced) gentleman say to check the alignment in the coupler between engine and transmission, and even though everyone in the service department said there's no way that could possibly be the problem when they finally went down and checked it was out .060" Once they aligned it the noise disappeared.

-Tom

That would change the orientation of the trailing edge of the prop; however, it seems a bit of a stretch. But, easy to check and if it's out, it should be trued up.

 

[Jeremygavin]

I can't answer your question, but can say I had a similar albeit slightly different sound from the port side in my 410DA a few years ago, and like you after prop reconditioning, etc it was still there. I had one older (more experienced) gentleman say to check the alignment in the coupler between engine and transmission, and even though everyone in the service department said there's no way that could possibly be the problem when they finally went down and checked it was out .060" Once they aligned it the noise disappeared.

-Tom

Thanks for the idea. It is something I can check with the boat in the water so that is a plus.

 

[Jeremygavin]

I am planning on moving the boat back to my home slip on Saturday. Anyone else with any theories or thoughts on this? I am going to speak with the the prop place that worked on the props this winter tomorrow morning to get their take on it a well.

 

[sbw1]

Tell us how it turns out.

 

[Jimmy Buoy]

I had the same noise on my Sbd shaft a few years back. It happened right after wrapping an 8' length of stray rope around the shaft which was discovered after running the boat at speed for about 10 minutes. The auto engine sync was having a difficult time getting both engines to sync, so we stopped, dove under, discovered and removed the wound rope. The boat operated afterwards nominally, but it sang when in gear near idle speeds. The strut bearings looked ok, but I replaced them anyway which eliminated the singing.

My guess is that the rope interrupted water flow into the bearings long enough to overheat just enough to bugger up the rubber surface.

If you've ruled out props, that might be your issue. Good luck!

 

[Jeremygavin]

I had the same noise on my Sbd shaft a few years back. It happened right after wrapping an 8' length of stray rope around the shaft which was discovered after running the boat at speed for about 10 minutes. The auto engine sync was having a difficult time getting both engines to sync, so we stopped, dove under, discovered and removed the wound rope. The boat operated afterwards nominally, but it sang when in gear near idle speeds. The strut bearings looked ok, but I replaced them anyway which eliminated the singing.

My guess is that the rope interrupted water flow into the bearings long enough to overheat just enough to bugger up the rubber surface.

If you've ruled out props, that might be your issue. Good luck!

How long did you run it with the noise before you changed out the strut bearing?

 

[Jimmy Buoy]

Ran it the remainder of the season (maybe another 20hrs) since there was no vibration issues and changed them during the winter. More experienced boaters than I said it would be fine since the shaft didn't have excessive plan within the bearing. They were right. The old bearing didn't really look all that worn or damage either. The rubber did seem to be rather flattened and hard compared to the new bearings though.

 

[hottoddie]

My spring loaded shaft grounding brushes make a similar once in awhile. If the noise is consistent and always in the same RPM range then I doubt that would be your problem.

 

[ttmott]

Can you turn the shaft by hand? Mine are difficult to start turning by hand but they do and they are both about the same effort to turn.
If you can't turn by hand then put a strap wrench on them and verify they both turn with about the same effort.
There should be little hatches to access the top of the strut bolts and bonding cables; maybe open those up and listen to the port strut through a screw driver or stethoscope on the bolts then listen to the starboard one and compare. If you can determine the noise is in-fact the strut/cutlass then might want to send a diver down to investigate.

 

[Jeremygavin]

Can you turn the shaft by hand? Mine are difficult to start turning by hand but they do and they are both about the same effort to turn.
If you can't turn by hand then put a strap wrench on them and verify they both turn with about the same effort.
There should be little hatches to access the top of the strut bolts and bonding cables; maybe open those up and listen to the port strut through a screw driver or stethoscope on the bolts then listen to the starboard one and compare. If you can determine the noise is in-fact the strut/cutlass then might want to send a diver down to investigate.

I had the same noise last fall so I was paying attention to it this winter when it was out of the water. The cutlass bearing looked good to me and looked the same as the starboard shaft. I could turn both shafts by hand using the prop when it was out of the water. Not too hard to turn and the effort was similar to turn either shaft. There was no noise when turning by hand on either shaft. When running the sound is very easy to determine it is coming from the strut area. When I am in the bilge above the port strut the sound is coming from right underneath but the prop is right there as well so that’s why I am sticking trying to figure out if it is prop sing or the cutlass bearing. I have pics of the props when they were done taking pitch out and tuning them so I am going to go to the prop shop tomorrow morning and verify that they really did put anti-sing edges on them.

 

[Jeremygavin]

My spring loaded shaft grounding brushes make a similar once in awhile. If the noise is consistent and always in the same RPM range then I doubt that would be your problem.

I don’t thing I have shaft grounds but maybe I do, what do they look like?

 

[Jeremygavin]

Ran it the remainder of the season (maybe another 20hrs) since there was no vibration issues and changed them during the winter. More experienced boaters than I said it would be fine since the shaft didn't have excessive plan within the bearing. They were right. The old bearing didn't really look all that worn or damage either. The rubber did seem to be rather flattened and hard compared to the new bearings though.

I am hoping to be able to run it for May before it could come out for repair in June. I have Zero vibrations and noise goes away around 1300rpms so once I am moving along there seems to be nothing wrong. Once the sound goes away there is no noticable difference in sounds above the port and starboard struts.

 

[hottoddie]

I don’t thing I have shaft grounds but maybe I do, what do they look like?

Mine are a copper strip about a foot long with a carbon brush at the end. The brush rides on the prop shaft behind the drive coupler and the other end attaches to a stringer. There is a spring that keeps pressure on the copper arm and there is a green bonding wire that attaches to the copper arm as well. I have "Drive Savers" installed on my shafts that isolate the shafts from the bonding system and the grounding brushes provide that bonding connection.

In your case I would check the shaft alignment and once that is good I would run the boat as I doubt you have a serious problem.

 

[Jeremygavin]

Got to the boat tonight and I can spin the port shaft fairly easily by hand at the engine coupler. Takes the same effort to spin the starboard shaft. I spoke with the prop shop that did the work and they said that it sometimes take a little work to get rid of the prop sing. So I am in the same place as before. I am going to run it 2.5hrs back home tomorrow morning and take it from there. Thanks for the ideas on what my issue might be.

 

[Jeremygavin]

As a follow up to my port shaft noise. I ran the boat all of May putting about 15hrs on it and the noise didn’t get better or worse. It seemed to be quieter when first running and be louder after a longer run which solidified the theory it was the strut bearing. I had the boat hauled this week to put in a new strut bearing and check the alignment. The yard manager said the strut bearing did show some signs on delamination and the shaft was a little out of alignment so I thought I was all set and my noise would be gone. Went for a ride tonight and the sound is still there with no change. I am not sure what else it could be other than prop sing that wasn’t corrected when I had the props reworked. I will run it this way this season and have the props pulled in the fall to have them try to get the anti-sing edges correct.