Deprecated: Function set_magic_quotes_runtime() is deprecated in /var/www/vhosts/tartan37.com/httpdocs/t37forum/common.php on line 88 Tartan37.com • View topic - Vibration under load

Tartan37.com

Tartan 37 Owner's Forum - Ride the wind, but look good doing it!
The time is 29 Mar 2024 03:24

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 7 Posts ] 
Author Message
 Post subject: Vibration under load
PostPosted: 13 May 2015 15:03 
Offline
Rail Meat

Joined: 21 Apr 2015 13:17
Posts: 10
I have the Universal 40 and I was wondering how much vibration is normal under load. I have two sweet spots at 1800 rpm and 2100. At these speeds the vibration is much less than other rpms. To give you some kind of measurement the latches on the cockpit lockers raddle at all rpm except the 2 sweet spots. I have checked the alignment at the coupling and it is within specs. I have the 2 bladed prop. And have not pulled it to check for balance or shaft bend. My guess is the engine mounts have never been replaced.
Jeff


 
 Profile Email  
 
 Post subject: Re: Vibration under load
PostPosted: 13 May 2015 19:15 
Offline
Skipper

Joined: 10 Nov 2006 22:56
Posts: 171
Location: Portland, Oregon
I replaced my OEM engine mounts on Betty Lou, along with a new shaft, cutlass bearing and shaft coupling and experienced a big reduction in vibration.

_________________
Jay and Muki Kerr
Tartan 37 Betty Lou (formerly Rainbow)
Hull # 118, fin keel
St. Helens, OR
Betty Lou's Blog


 
 Profile Email  
 
 Post subject: Re: Vibration under load
PostPosted: 14 May 2015 13:09 
Offline
Skipper

Joined: 27 Oct 2006 10:32
Posts: 827
Another cause can be attributed to prop fouling. Any barnacles?

Alpinista, Which mounts did you use for replacements? I am ready for some too................


 
 Profile Email  
 
 Post subject: Re: Vibration under load
PostPosted: 15 May 2015 12:41 
Offline
Rail Meat

Joined: 21 Apr 2015 13:17
Posts: 10
Skipper,
Found this review for the DF-2207-2 mount: http://svrainshadow.com/?p=1039
I think this is what Tartan used with the Universal 40 engine
Jeff


 
 Profile Email  
 
 Post subject: Re: Vibration under load
PostPosted: 16 May 2015 09:33 
Offline
Skipper

Joined: 27 Oct 2006 10:32
Posts: 827
Thanks for the link Jeff,
Ironically, those were the mounts I was thinking about. Westerbeke sells some really nice mounts but they are prohibitively expensive. Here's a good article covering the process and the choices made: http://www.pbase.com/mainecruising/motor_mounts

Cheers,
Tom


 
 Profile Email  
 
 Post subject: Re: Vibration under load
PostPosted: 23 May 2015 06:41 
Offline
Skipper

Joined: 29 Dec 2006 09:38
Posts: 656
It might be your mounts accounting for the vibration, but replacing them would not be my first thought about the source of the vibration. Here are some thoughts:
1. Are the all the nuts on the engine mounts secure? Especially the top ones. The alignment can appear OK at rest but the engine could be loose. Just one can make vibration a problem.
2. Zincs on the shaft. Very common for yard folks (or owners) to not tap the zincs with a hammer to secure them tightly when they are installed. If this is not done it a common problem. Subsequently, they loosen and cause the symptoms you describe. Usually very quickly after splashing.
3. Was the boat just launched? Could be that the Travel lift strap bent your shaft a bit or caught your prop. I had the yard bend a shaft this way on another boat I had.

I do not think that sudden shaking would be caused by motor mounts failing. They generally fail slowly..... vibration just gets slowly worse. But maybe you just noticed it.

Just thoughts FWIW

Ray
Velera #373


 
 Profile Email  
 
 Post subject: Re: Vibration under load
PostPosted: 02 Jul 2015 10:35 
Offline
Skipper

Joined: 14 Jul 2012 20:36
Posts: 495
Location: Norfolk, Va
The motor mount bolts is a good thing to check, I had one shear off. Those mounts get a workout, all the force pushing that 15,000lb boat thru a head sea is transferred to the mounts. Replaced mine when I rebuilt the motor and they were shot at 1,800 hours.

I only have a few sweet spots RPM wish with less variation past 1,500

_________________
Hull #208, Puff Card
Southern Chesapeake Bay


 
 Profile Email  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 Posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 15 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Powered by phpBB © 2002, 2006 phpBB Group