Good post Rick, but one quibble.
If an engine has flexible mounts then it must have a solid not flexible 
coupling and vice versa.

I made that mistake when I repose red my last boat and the coupling destroyed 
itself with extreme prejudice in a couple of hours of running.  Everything was 
aligned but the two components worked against each other. 

I learned later that this is an inflexible rule ;-)  sorry I can't provide a 
reference but my painful experience bears it out. The original had a solid 
mount and flexible coupling and the new engine had flexible mounts so I used 
the very substantial coupling.  


Don Newman
C&C 44


> On Dec 11, 2013, at 14:45, Rich Knowles <r...@sailpower.ca> wrote:
> 
> Josh:
> 
> I just had a look at mounts on the PYI site: 
> http://www.pyiinc.com/index.php?section=rd_marine&action=engine-mounts&sn=1
> 
> Their widget allows you to insert the dimensions of your existing mounts so 
> you can receive new mounts that should simply replace the  existing units 
> with no drilling or other fiddling. I trust you completed that exercise and 
> have received the correct units. Note, they are not stainless but zinc plated.
> 
> Many of our boats came with some sort of metal members in the engine mounting 
> system and I suggest leaving well enough alone unless you have good reason to 
> make changes. If you do one mount at a time, you should be able to simply 
> undo the bolts, back off the positioning nuts, remove and replace the old 
> mount and, after all have been replaced, adjust the mounts to position the 
> engine correctly.
> 
> Well before you start, I suggest soaking the mounting bolts and nuts and your 
> propeller shaft flange connecting nuts and bolts with one of the proven rust 
> busters previously discussed on this forum.
> 
> Also, before you undo the existing mounts or make any changes to the 
> adjustment nut positions, I suggest you measure and record the distance 
> between the underside of each engine mounting bracket to the top of the bed 
> under it and use that measurement to set the top of the bottom nut of each of 
> the new mounts. Even if an old mount has settled, it will give you a 
> reasonable starting point to start aligning the engine.
> 
> Aligning the engine after installing the new mounts will be another chore. 
> This involves undoing the bolts connecting the propeller shaft flange to the 
> engine shaft flange and fiddling with the nuts on the mounts until the shaft 
> is centred in the shaft tunnel, the flanges are concentric and the engine is 
> aligned so the clearance between the flanges is equal or within .001 - .002" 
> all around. This can be a tricky job and will test your patience, but needs 
> to be done as best as possible. After this is done, the system should be 
> reasonably vibration free. Ideally the final alignment should be done after 
> the engine has settled on the new mounts for a few days and the boat is in 
> the water.
> 
> To reduce alignment and vibration problems further, I highly recommend 
> installing a flexible shaft coupling which will absorb most of the remaining 
> shaft coupling misalignment which is inevitable, especially when the system 
> transitions from a static state to an operating, loaded condition.
> 
> See: http://www.pyiinc.com/index.php?section=rd_marine&action=shaft-coupling
> 
> Google will reveal many discussions of shaft alignment on the web. One of the 
> simplest illustrations is: http://www.ebasicpower.com/faq/alignib.htm
> 
> I also suggest checking your cutless bearing while you are fiddling with the 
> drive train. Note the spelling, it's not a sword:)
> 
> Good luck.
> 
> Rich Knowles
> INDIGO LF38
> Halifax, NS.
> 
> 
> 
> 
> 
> On Dec 11, 2013, at 7:33 AM, Josh Muckley <muckl...@gmail.com> wrote:
> 
> Hey Folks,
> 
> I'm in the process of replacing my engine mounts on Sea Hawk, equipped with 
> the original Yanmar 3HM35F.   I purchased mounts from PYI.  They look to be 
> quite high quality mounts and appear to be made of SS.  Unlike OEMs, they are 
> positively captured so your engine won't go flying lose if the rubber  
> separates.
> 
> The previous mounts were not OEM either.  In fact it appears that the PO may 
> have over loaded them or installed used mounts because the forward pair 
> appeared very compressed, almost a 1/2 in shorter and kind of inverted on 
> themselves.  At first glance I thought they were different designs from the 
> aft pair.  Because they were short it looks like the PO had to build up the 
> forward foundations with some 5/8 or 1/2 inch starboard (polyethylene) blocks.
> 
> Sitting between the engine mounts and the glassed in foundation of the boat 
> there are 1/2 inch thick aluminum plates.  They run the full length and width 
> of each port and starboard foundation rail.  Because of the clearly 
> redesigned nature of the situation I began to question if these aluminum 
> plates should be there or if they too were part of the PO's engineering.
> 
> I'm looking for thoughts and advice regarding the engine mount replacement 
> task as well as the appropriateness of the aluminum plates.  It would also be 
> helpful if anyone has torques specs or design details of the fiberglass 
> foundation.
> 
> Thanks,
> 
> Josh Muckley
> S/V Sea Hawk
> 1989 C&C 37+
> Yanmar 3HM35F
> Solomons, MD
> 
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