method of attaching V8 mercruisers to engine beds on wood stringers,

[chrome dome]

boat is a 30 ft flybridge cruiser with near new twin 315 hp mercruiser donks, wide engine beds on wood stringers,
question is what type of bolts etc should be used ( by a pro installer ) to fit the motors to the beds?

found two very loose coach bolts....one much smaller than the other...which would explain the sudden vibration that appeared a couple of weeks ago,
replaced one, tightened the other, vibration gone now but am concerned about any damage that might have happened to the stringer...or anything else..

first inboard boat but not our first boat LOL...are coach bolts commonly used....or at least the right size ones....commonly used to attach large, heavy V8 motors to motor beds?

 

[Woodonglass]

You're not my old high school principal are you!!! We used to call him Chrome Dome!! You'd be amazed at the variety of fasteners and methods that I've seen used to hold down motors to stringers here on the forum. They ALL have worked to some extent. I would think that a PRO would advise you to use Stainless Steel fasteners in some fashion and to bed them in epoxy or 3m 5200 to ensure a good bond. That's what I'd recommend.

 

[Bondo]

boat is a 30 ft flybridge cruiser with near new twin 315 hp mercruiser donks, wide engine beds on wood stringers,
question is what type of bolts etc should be used ( by a pro installer ) to fit the motors to the beds?

found two very loose coach bolts....one much smaller than the other...which would explain the sudden vibration that appeared a couple of weeks ago,
replaced one, tightened the other, vibration gone now but am concerned about any damage that might have happened to the stringer...or anything else..

first inboard boat but not our first boat LOL...are coach bolts commonly used....or at least the right size ones....commonly used to attach large, heavy V8 motors to motor beds?

Ayuh,.... Generally speakin' the iron motor mount is Lag bolted to the wooden motor bed,...
Generally 1/2" Lag bolts, a few inches long, 'n a flat washer of course,... depends on the depth of the wood available,...

Was the wood under yer mount wet,..?? Rotted,..??
That's generally the cause of loose motor mount Lag screws,...

 

[Rickmerrill]

I'd want to check for any physical damage, water or rot and make sure nothing moved out of alignment just to avoid bad dreams at night.

 

[jbcurt00]

Ayuh,.... Generally speakin' the iron motor mount is Lag bolted to the wooden motor bed,...
Generally 1/2" Lag bolts, a few inches long, 'n a flat washer of course,... depends on the depth of the wood available,...

Was the wood under yer mount wet,..?? Rotted,..??
That's generally the cause of loose motor mount Lag screws,...

Yep, my thought EXACTLY......

 

[Watermann]

On my wood motor mount bed that were new, I pre drilled the holes, squeezed some 5200 in the holes and ratched in some 1/2" x 3.5" stainless lag bolts.

 

[chrome dome]

sorry for delay in replying tried but got 'not authorised to post' message,
no not clever enough to be a school principal LOL
stringers were checked before beds were made, neither is wet, damp or soggy now,

vibration turned out to be a broken drive shaft, just inside the hub, probably caused by the loose engine mount, boat being slipped tomorrow so shaft can be replaced,
will see if any of this is under warranty, not confident though