Westerbeke 12d diesel mounted on lag bolted wood blocks

[DougR]

Originally Posted by skkeith

The facing process is news to me DougR. I am trying to do this in the water. A split coupling will make this not necessary? Can you recommend a supplier for a quality clamp coupling, the solid coupling is 50MC004075 Solid Buck Algonquin Marine Motor Coupling.

Common manufacturers of split (clamp) couplings are: Buck Algonquin, Walters Machine Co., R&D Marine

Technically, the coupling should be faced true to the shaft regardless of whether it is a solid coupling or a split coupling.....

The fit between the prop shaft and the inner diameter of the coupling is also critical, probably more so on a solid coupling than on a split coupling.

Given that you are doing this job in the water, and also given the condition of the front of your prop shaft, I think I would opt for a split coupling as there is a bit more forgivability in dimensions with these couplings.

I suggest you do a bit of searching on line for an article written by Steve D’Antonio titled “Shaft Couplings”, published in Professional Boatbuilder Magazine. Very comprehensive and informative. Steve also has several other shaft and coupling articles that may be helpful as well.

DougR

[skkeith]

Engine did not break off the mounts, I took it off after the split coupling broke. From pic 2 my novice diagnosis is engine mis alignment.

[skkeith]

I read through Steve D'Antonio's article (again) I had already seen it randomly googling, and it is good stuff however not really good for me putting everything together in the water. I am unable to go on the hard for many months at lest. When I do I will replace this short shaft but I am hoping to get through a season with what I can do myself in the water. What do we think the consequence of using an un-faced new straight coupler for a season would be. would it just break before long? Also I have considered a flexible coupler but Steve D does not seem to endorse them highly. Opinions?

[stormalong]

Originally Posted by skkeith

I read through Steve D'Antonio's article (again) I had already seen it randomly googling, and it is good stuff however not really good for me putting everything together in the water. I am unable to go on the hard for many months at lest. When I do I will replace this short shaft but I am hoping to get through a season with what I can do myself in the water. What do we think the consequence of using an un-faced new straight coupler for a season would be. would it just break before long? Also I have considered a flexible coupler but Steve D does not seem to endorse them highly. Opinions?

I have a Vetus type 6, in place for 15 years and working fine. This flex coupling does not add any length to the shaft but might be a bit large for your installation.

[DougR]

Originally Posted by skkeith

I read through Steve D'Antonio's article (again) I had already seen it randomly googling, and it is good stuff however not really good for me putting everything together in the water. I am unable to go on the hard for many months at lest. When I do I will replace this short shaft but I am hoping to get through a season with what I can do myself in the water. What do we think the consequence of using an un-faced new straight coupler for a season would be. would it just break before long? Also I have considered a flexible coupler but Steve D does not seem to endorse them highly. Opinions?

I doubt that a solid coupling or a split coupling will fail if installed correctly and properly aligned. My concern with a solid coupling is that it will be impossible to get a proper fit between the shaft and the coupling given your in the water conditions.

Ideally, a solid coupling should be a “light interference” fit on the shaft, requiring light tapping to get it on the shaft, and this is difficult to obtain without a machine shop, especially given the condition of your prop shaft. My opinion is that in your circumstances you can get a better grip on the shaft with a split coupling.

As far as “why the original coupling failed” , its always difficult to make that judgement from a couple of photos, but I see several things that stand out to me....
- I don’t like the way the original coupling was made....it looks like the clamped on piece wasn’t connected to the body of the coupling. Most split couplings start life as one piece and are much more robust that what I see there.
- the engine was installed with Bushings Inc. DF mounts on the rear and Metalastik mounts on the front. The DF mounts are made with circular rubber inserts, so if the mount is rotated a little it isn’t important. The mount can take force more or less equally in any direction. But the Metalastik mounts have rubber at the front and at the rear of the mount, so they have to be orientated fore and aft for the mount to properly accept the engine thrust. But they were installed twisted on the engine bed. This might have caused the engine to rotate under prop thrust, causing misalignment, bending, and ultimately failure of the coupling clamp bolts.

[Peter1949]

Impressive dialog on how did it happen to how to fix in and out of the water.
Looking forward to read progression on the Islander

[skkeith]

So this situation has gotten much worse and also somewhat better at the same time. Usually when things go completely wrong for me I am too embarrassed to post the results for all you to laugh at. This time I must do it hopefully to save someone's life. If you are a novice contemplating engine alignment please read on.

Last time we checked in I was contemplating how to fabricate motor mounts and mount them in the water. I figured the best way to start this process was to completely remove the engine. Since it is only about 240 pounds, this was the easiest thing I did. It took me less than an hour to remove the engine completely



Next step completely clean the engine compartment in preparation for painting. During the cleaning I carefully inspected the stuffing box and had a small(ish) heart attack after finding a bulge underneath where it could not be seen. This turns out to be the good part! I called up Breakwater Cove ( boatyard in Monterey ), and showed them the bulge, and suddenly instead of looking at 3 months to hard time, I was out of the water that day. Kudos to Larry for saving my bacon.

So as it turns out the person who 'engineered' the motor mounts also used motor mounts with nuts missing, both had no lock nuts ( see picture below ) and one was also missing the top nut. You can see a good inch of stripped threads where the motor was moving up and down. Also behind you can see the pine 2x4 used as a shim for the motor mount.



But the motor mounts turned out to be the least of my troubles. The strut hanging the cutlass bearing and the cutlass bearing itself were both completely shot. It was so far out of alignment it even wore a grove in the stern tube!



After getting the estimates from the fiberglass guy I was thinking things were not quite as bad as I thought, then I went and removed the stuffing box.





The stern tube had a hole burned through it. The stuffing box nearly melted through as well. All in all I feel happy to be alive, of course I don't know what the bill will be yet.

[DougR]

About the only thing I can say is Yipes!

It certainly looks like someone threw that engine in there as a “make do” solution to get the boat powered after perhaps a prior engine failed.

The “split coupling” that we had discussed isn’t a split coupling at all, but is better described as a “muff coupling”. The transmission is fitted with a standard solid coupling, and the muff coupling is added on to a short piece of prop shaft in a failed attempt to lengthen the original prop shaft. Probably an original engine/ transmission was longer overall and didn’t need the muff coupling to reach back to the original prop shaft.

Muff couplings aren’t necessarily bad, as they are commonly used on large motor yachts and sport fishing boats to couple two long shaft sections together, but they are always placed in a location where the shaft is supported by two or more bearings. In your case the engine end of the coupling was free to move around with the engine, and that overloaded and fatigued the coupling bolts.

If you plan to locate the engine in the same location as was shown, you need a longer propeller shaft.

Might not be a bad idea to replace that grey plastic hose barb piece in the exhaust hose as well......I would be concerned about it’s ability to stand the exhaust temperature in that location. Looks like another attempt to couple a different engine to an existing location.

[skkeith]

For the record, I have a new longer shaft on order. I have a Buck Angiquin coupler for it (split coupler).

Please vet this motor mount bracket idea:

I was planning on putting the angle irons flush over the stringer, so I wanted to tap the 3/8" steel instead of using a nut underneath (between stringer and angle iron). Is this tapping idea dumb, should I just sim up underneath for nut access?

[stormalong]

Originally Posted by skkeith

For the record, I have a new longer shaft on order. I have a Buck Angiquin coupler for it (split coupler).

Please vet this motor mount bracket idea:

I was planning on putting the angle irons flush over the stringer, so I wanted to tap the 3/8" steel instead of using a nut underneath (between stringer and angle iron). Is this tapping idea dumb, should I just sim up underneath for nut access?

If you are going that thick on the angle iron tapping works fine. For your size engine I doubt that 3/8 is needed. As for shimming, you need to make the top of the two brackets as close to being on the same plane as possible. That is what you should aim for. Any differences can be made up in the engine mount adjustments.

Just two things:
Be sure that your bolts are secure and won't loosen from the engine vibration.
It is best to have the engine sitting as low as possible on the engine mount studs to minimize engine movement and stress on the rubber portion of the mounts.

[DougR]

Here's a photo of angle irons installed and thru bolted over the original stringers. The replacement engine had the front and rear mounts the same width and on the same vertical plane, but the new gear box has a drop center output instead of being on the crankshaft center line. This required cutting down the original beds and installing the angle iron. As I recall the angle iron was 4 x 4 x 3/8". Four 1/2" bolts thru the engine bed per side, and the flex mount bolt holes were drilled and tapped.

In your case you might sister the engine bed to get the front mount width correct, or turn the angle flange inboard.

This was for a 55h.p. engine.

[sanibel sailor]

I believe Dave Gerr recommends against an L bracket to the stringers, although his book is remote from me and I don't recall the reasoning.

[odonnellryan]

I was going to suggest you give your bearing and stuffing box a look over - but then I read to the end of the post!

I had a very similar problem. I am in the process of replacing my strut, stern tube, shaft, and coupling because of an engine that was very out of alignment.

Good news is we'll both have a repair we can rely on once everything is said and done...!

On my boat, the engine mounts were lag-bolted into fiberglass and wood under the stringers. I'm probably going to go this same route as there seems to still be some teeth there for the bolts to bite into - but I'll probably remove all the mounts and fill in the holes with thickened epoxy to ensure a lasting repair.

[stormalong]

Originally Posted by skkeith

So this situation has gotten much worse and also somewhat better at the same time. Usually when things go completely wrong for me I am too embarrassed to post the results for all you to laugh at. This time I must do it hopefully to save someone's life. If you are a novice contemplating engine alignment please read on.

Last time we checked in I was contemplating how to fabricate motor mounts and mount them in the water. I figured the best way to start this process was to completely remove the engine. Since it is only about 240 pounds, this was the easiest thing I did. It took me less than an hour to remove the engine completely

Attachment 213428

Next step completely clean the engine compartment in preparation for painting. During the cleaning I carefully inspected the stuffing box and had a small(ish) heart attack after finding a bulge underneath where it could not be seen. This turns out to be the good part! I called up Breakwater Cove ( boatyard in Monterey ), and showed them the bulge, and suddenly instead of looking at 3 months to hard time, I was out of the water that day. Kudos to Larry for saving my bacon.

So as it turns out the person who 'engineered' the motor mounts also used motor mounts with nuts missing, both had no lock nuts ( see picture below ) and one was also missing the top nut. You can see a good inch of stripped threads where the motor was moving up and down. Also behind you can see the pine 2x4 used as a shim for the motor mount.

Attachment 213429

But the motor mounts turned out to be the least of my troubles. The strut hanging the cutlass bearing and the cutlass bearing itself were both completely shot. It was so far out of alignment it even wore a grove in the stern tube!

Attachment 213430Attachment 213431Attachment 213432Attachment 213433

After getting the estimates from the fiberglass guy I was thinking things were not quite as bad as I thought, then I went and removed the stuffing box.


Attachment 213434


The stern tube had a hole burned through it. The stuffing box nearly melted through as well. All in all I feel happy to be alive, of course I don't know what the bill will be yet.

What is image 5 of this post. Did I miss something in the text?

[DougR]

Originally Posted by sanibel sailor

I believe Dave Gerr recommends against an L bracket to the stringers, although his book is remote from me and I don't recall the reasoning.

Dave Gerr, and most other authorities, recommend against L brackets that are bolted to and cantilevered away from the engine stringers because of the possibility of introducing vibration into the mount system. That’s why in post #8 I recommended the welding of triangular gussets between the two legs of the angle iron to stiffen the assembly and avoid this problem.

When using angle brackets that are bolted to the engine stringer and overlap the stringer, as shown in the photo, the additional support offered by the stringer contact provides significant support to the angle, less bending load on the stringer, and vibration is seldom a problem.

In the case discussed here, the proposed angle iron has a thickness of 3/8” and the engine weighs 250 lbs. If this material actually goes into the boat, there won’t be a problem.