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Old 17-06-2016, 13:58   #31
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Re: How to find correct alignment?

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Originally Posted by capt-couillon View Post
Dead on the money.... Except reversed... Top and bottom give vertical deviation from center, side and side give horizontal. If you rotate shaft and clearances remain same, you know shaft is straight as well.
Absolutely. A good stainless feeler gauge set is a basic tool. Lots of places sell them.Get the set with the largest number of gauges. Be careful of the smaller gauges since they are literally wafer thin if not thinner.
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Old 17-06-2016, 14:00   #32
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Re: How to find correct alignment?

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Originally Posted by dick sargent View Post
The goal is to align the engine to the shaft, not the other way around. This is best done in the water. The shaft has to be centered in the shaft tunnel first. I use a piece of plywood with a saddle cut-out and clamp it somewhere in the engine compartment. After centering the shaft both up and down and side to side in the shaft tunnel, I secure it with the plywood jig. Next, I mate the transmission and prop shaft flanges to .003 of an inch or less using a knife type feeler gauge. Hopefully you have adjustable engine mounts. My engine weighs 1500# so I use s make-shift chain-fall to lift the engine slightly to easily adjust the mounts, either side to side or up and down. It will save the transmission and the engine will run more smoothly. I have heard of misaligned prop shafts sinking boats due to tearing up the shaft tunnels. Alignment, if properly done will save you a lot of grief.
Dick, I think if you expanded on the plywood jig to hold the shaft centered might help. Aligning the engine to a drooping shaft wouldn't be worth a damn. I can't speak to a dripless and apparently you can. I would think the plywood jig and a dial indicator would be the way to do it?
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Old 17-06-2016, 14:20   #33
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Re: How to find correct alignment?

For a quick and dirty way to align, loosen the engine mount nuts a bit, start the engine and put in gear. stay in low speed. When the engine stops, or slows down, its bouncing tighten the bolts X wise. At least that is what the repair guy did in ChristChurch to our engine as a quick way to get things lined up. You can also do a strobe test, but that would be gilding the lily.
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Old 17-06-2016, 14:33   #34
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Re: How to find correct alignment?

Itís not likely your shaft can slip out of the cutlass bearing and stuffing box (or whatever gland you have) unless it has been polished to a fare-thee-well within the last 24 hours. Crud grows overnight just about everywhere which likely will not allow the shaft to slip through both. I regularly remove my prop and shaft while the boat is in the water. I first polish the hell out of the shaft so it will slide smoothly, then I remove the prop to bypass the rudder. (My engine and shaft is offset 15 degrees to the center line. If you donít have an offset engine the rudder will probably prevent the shaft from falling completely out anyway.) As I withdraw the shaft I follow it up with a piece of PVC pipe with a cap glued on the end and tighten the stuffing box. (Yes, a 1 inch PVC is the exact outside diameter of my 1 and 1/8 inch shaft. Others might have to rework the PVC pipe to their shaft diameters) I hardly get a cupís worth of water in the bilge. I tie lanyards to all underwater parts before commencing this work.


Once I had aligned my shaft by the feeler-gauge method to within a micro-milli-mini thousandth of an inch in all four orientations and the 6 foot long shaft was straight as a string but the vibrations persisted. Then I sent the prop out to be re-sized, re-pitched, dressed and balanced and the vibration went away. It was the prop all along.
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Old 17-06-2016, 14:43   #35
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Re: How to find correct alignment?

The Coriolis effect must be effecting some repair guys brains. Thats too quick and dirty to be effective. and sure to lead to engine mount failure. The process has been pretty well covered here. And its not rocket sc . I'd mention that on long trannies like velvet drive the rear mounts may be on the engine. This makes the coupling tilt up when lowering the for'd mounts. Sorta counter intuitive .Also give some effort to put equal weight on each mount. Not balanced on 3 or teeter totered . ps. my starret dial indicator will not likely be used much and I'd pass the baton so to speak to a younger shipwright
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Old 17-06-2016, 14:59   #36
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Re: How to find correct alignment?

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The Coriolis effect must be effecting some repair guys brains. Thats too quick and dirty to be effective. and sure to lead to engine mount failure. The process has been pretty well covered here. And its not rocket sc . I'd mention that on long trannies like velvet drive the rear mounts may be on the engine. This makes the coupling tilt up when lowering the for'd mounts. Sorta counter intuitive .Also give some effort to put equal weight on each mount. Not balanced on 3 or teeter totered . ps. my starret dial indicator will not likely be used much and I'd pass the baton so to speak to a younger shipwright
Well it worked with a small yanmar on a yamaha 33. Long shaft. Later found out the shaft itself was bent, but it did provide a quick method for getting the engine where it wanted to be. BTW, it was a Japanese version, so low coach roof, engine in the bow of the boat, and shaft was relatively small diameter. So mounts were never an issue.
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Old 17-06-2016, 16:40   #37
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Re: How to find correct alignment?

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Originally Posted by reed1v View Post
For a quick and dirty way to align, loosen the engine mount nuts a bit, start the engine and put in gear. stay in low speed. When the engine stops, or slows down, its bouncing tighten the bolts X wise. At least that is what the repair guy did in ChristChurch to our engine as a quick way to get things lined up. You can also do a strobe test, but that would be gilding the lily.
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Originally Posted by reed1v View Post
Well it worked with a small yanmar on a yamaha 33. Long shaft. Later found out the shaft itself was bent, but it did provide a quick method for getting the engine where it wanted to be. BTW, it was a Japanese version, so low coach roof, engine in the bow of the boat, and shaft was relatively small diameter. So mounts were never an issue.

Actually, the procedure described was a good way to bend a shaft....

Really a stupid way to do it.
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Old 17-06-2016, 19:05   #38
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Re: How to find correct alignment?

if the seal is not leaking the shaft is not vibrating the boat steams well leave it alone
its not broken
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Old 18-06-2016, 05:19   #39
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Re: How to find correct alignment?

About the square head set screws used to fix the coupling flange to the prop shaft. The set screws should be aligned with the indent(s) that have been machined into the prop shaft.

I always use Lanocote on these two screws as my flange is iron and the set screws are iron and if the set screws "freeze" in their holes, it is really easy to twist the square heads off and then...

Of course, safety wire them when everything is set correctly.
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Old 18-06-2016, 07:13   #40
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Re: How to find correct alignment?

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Originally Posted by Cheechako View Post
Me too, never had one that wasnt self aligning. I pretty much quit using feeler gauges, instead I use a nice drill bit. Put it in the gap 4 places to determine where it's at. You get a feel for it. .005 or less is readily determined with eyesight or feel.
x 2. Precisely ! When you consider that a Cal-40 " banana'd " 2+" when rigged and tuned in the mold. makes all this dial indicator stuff superfluous.
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