How To Engine Alignment

[bailsout]

When I removed and replaced my engine I discovered that the alignment was off: Enough to feel the vibration while sailing in neutral and then looking at the spinning prop shaft wobble. I removed the flex coupler and then did lineup directly- face to face adjusting motor mount nuts. No feelers gauge or dial. Runs incredibly smooth. I think I got lucky.

[Oceanride007]

I use to align large pumpsets with solid couplings, under ideal circumstances I did and still can align to exceptional accuracy.
However a recent alignment check on a 65' gave me course to take a pull. Because the shaft coupling was hidden by a bulk head.
You realise already that fiberglass hull is flexible and the accuracy will be different between alignment on the hard against alignment in the water.
I don't think you made it clear that the new engine is different from the original, in that case Roy M contribution would be good for you to know.
Of course the important bit is the alignment of the couplings, if there is any shaft bend makes it tough but not impossible, check it, if faulty, straighten it. If you can't, all is not lost.
Alignment between the output shaft of gear box and Prop shaft is important in regard to noise, wear of bearings, failure of coupling bolts. I would aim for .005" or less East West, North South across the coupling, so long as the aft bearings do not cause a bend to shaft knowing that alignment thru Cutlass need not be perfect and the flexible mounts of engine is a variable that you cannot control.
As you only have one shaft held reasonably firmly, you may need a dummy spacer, dial indicator, or feelers, or slip gauges, to measure your alignment across the face of the coupling, you have most likely prop shaft wabbly, would think your dummy spacer should have spigots to hold both shafts true, whist you turn and measure.
Sorry, difficult to descibe a Skill learnt as a apprentice Fitter (so long ago). But its logical, don't fear it, you can figure it out.

[tinkrman69]

If you have a shop and lots of tools, you could go through all the steps and make a gig and look top notch whilst doing the job. Or you could set the engine in with the probable mounts and check the hight on the out put shaft to the prop shaft. adjust up with shims if needed...up to half inch. if you need more then make stringer higher...remembering that a metal backing will need to be accessible inside the stringer...ie...add one if needed. the same applies if you need to lower the stringer. be reminded that you can get different mounting brackets for the engine to change width and hight of tabs that sit on motor mounts. Once the shafts are with in a 1/4 inch or so up and down you can adjust the rest ...up and down and side to side with the motor mounts. mark the bolt holes when aligned and slide the engine to make room to drill and tap the mounting holes into the stringer.

I've repowered several boats both at the dock and on the hook, cut a few shafts too. It's pretty simple and with a little fore thought can be done in just a few days. with basic tools. when aligning take into account the condition of the strut or cutless barring and insure the shaft is centered in the shaft log. no special tools needed, just feel it, it should have any binding. a dial indicator is nice for lateral and vertical alignment. but if you getting the outer edge of the flange really close and using feeler gauges to adjust the gap betwixt them at 12,3,6,9 o'clock will be well with in tolerance. I've never had to go back and fix an install and I'm always called back for other work. Always try to keep the money around for more pleasurable thing and if you have so much it doesn't matter give some to someone who needs help. there are plenty of willing to work hard "oppressed" people around who could use a helping hand.

PEACE LUV & HAPPINESS

[brantleychuck]

I've done it twice, . I just hung the new engine in place, figured out where I needed support. Raised engine back up . Built supports. Lowered engine back down. Made adjustments as I went. A RD flexible coupler comes with instructions on how to get nearly perfect alignment with feeler gauge. No magic


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[deblen]

Info that may be useful re new shaft & coupling

A New Prop Shaft Photo Gallery by Compass Marine How To at pbase.com


Cheers/ Len

[hamburking]

Originally Posted by Guy

From what I have heard, some boats (fin keel) can flex enough from the support stands to being in the water, to need another alignment.

Too true. Engine installed on the hard, all aligned perfectly, then splash and whoa, bad alignment. On the hard the keel pushes up on the hull, but in the water, it pulls down hard. Also, don't forget the rig...it puts the whole hull in tension, like a bow and arrow. Be sure to tune the rig, wait a couple days, tune the rig again, and then do your final alignment on the engine. A flexible coupler and dripless shaft seal would make life a bit easier I imagine, but I wouldn't know.

When my volvo 2002 runs, it bounces and dances like crazy. Especially at low rpm, like idle speed. I can't understand how it doesn't rip the shaft out of the hull sometimes. Its smoother at higher rpm. The aft mounts are big flexible rubber jobs, but the forward mounts are solid. I'm fairly certain the alignment is fair, because the shaft spins easily when I sail. Vibration and noise when motoring, yes, plenty. But its been like this for years, no worse for wear that I can tell. Comments?

[deblen]

Originally Posted by hamburking

Too true. Engine installed on the hard, all aligned perfectly, then splash and whoa, bad alignment. On the hard the keel pushes up on the hull, but in the water, it pulls down hard. Also, don't forget the rig...it puts the whole hull in tension, like a bow and arrow. Be sure to tune the rig, wait a couple days, tune the rig again, and then do your final alignment on the engine. A flexible coupler and dripless shaft seal would make life a bit easier I imagine, but I wouldn't know.

When my volvo 2002 runs, it bounces and dances like crazy. Especially at low rpm, like idle speed. I can't understand how it doesn't rip the shaft out of the hull sometimes. Its smoother at higher rpm. The aft mounts are big flexible rubber jobs, but the forward mounts are solid. I'm fairly certain the alignment is fair, because the shaft spins easily when I sail. Vibration and noise when motoring, yes, plenty. But its been like this for years, no worse for wear that I can tell. Comments?

My VP2003 was same way-like bucking bronco. Removed eng. to repair oil leak @ tube for mech. gauge I had instd. Found 3 broken rubbers. It's now much better & I put safety chains on for good measure. Catching a couple of potwarps in prop,stalling eng.,& 25yrs will do that guess.

[Delancey]

Back in the water after two weeks on the hard. Don't want to do that again. Yuck. What did I learn from the rough install?

Stringers will lie to you. They are crooked bastards not to be trusted.

Also, a clever friend figured out that the right diameter line will hold the shaft steady in the center of the shaft log, just like packing a stuffing box. And that to your bag on tricks.