Engine alignment - DIY?

[GHA]

Do I really need to get someone in to do the alignment on a newly installed beta 35 with a R&D flexible coupling?

Don't mind spending the money really but is it that hard?

Haven't spent too much time on it yet but it didn't take long to get the left/right up/down close, and just lying ontop on the engine seemed to be enough to throw the up/down out a tiny bit.

So if you go for bang on stationary won't the engine be a little out when it's pushing full thrust? (Steel boat so won't change shape between in and out of the water.)

Might have a go at the feeler gauge alignment this afternoon and see how that goes, but is it some black magic art witch only the chosen few can perform?

All thoughts/experience very welcome. Ta

(R&D instructions.. http://www.randdmarine.com/flexiblescinst.asp )

 

[alahol2]

Must admit when I did mine (titchy 13HP Beta) I didn't find it overly difficult. It just took a fair bit of brain power to think 3 dimensionally and be willing to alter all four feet at the same time if necessary. There is no point at which you can say "that foot is OK, lock it", and, even having finalised and locked the feet, to be willing to unlock and re-adjust.

 

[<152587>]

Engine alignment is a touchy subject. I remember doing engine alignment on 100' wooden boats fitted with Paxman YHAM engines. The alignment would alter radically when launched so after sea trials we would measure the height with an internal micrometer then the tool room would produce a set of gauges to check the alignment periodically.

lately have done alignment on several yachts and one in particular stands out. Tomahawk 25, heads door would not close by about 3/8" whilst ashore in cradle but ok when launched so obvious that a certain amount of movement in the hull is to be expected. you may experience this on, particularly tankers in rough weather when stood on the bridge aft, the mast on the focsle is at a pronounced angle.

The general rules I follow are do not lean on the engine, get it near enough on shore and finalise alignment afloat after a short run to settle mounts.

 

[GHA]

The general rules I follow are do not lean on the engine, get it near enough on shore and finalise alignment afloat after a short run to settle mounts.

Ta, long keel steel boat with 8mm plate keel so can't see that deforming much but letting it bed in for a good few hours underway in the water then check again seems to be common advice.


http://www.ebasicpower.com/faq/alignib.htm

 

[zambant]

Sure is a DIY job if you can use a set of feeler gauges and you have a coupling that makes it easy to measure.
As others have said - do it before launch, again when in the water, run the engine in gear for a few mins and check for any vibration, check it again and then go for a run and check it again.
Seems like a bit of a long winded affair but if you get it right after its been in the water it shouldn't alter by much.
There is lots of info on the net
Fair winds
John

 

[Tranona]

Ta, long keel steel boat with 8mm plate keel so can't see that deforming much but letting it bed in for a good few hours underway in the water then check again seems to be common advice.


http://www.ebasicpower.com/faq/alignib.htm

Should not need rechecking on a steel boat. The biggest problem is usually working out which way to adjust the mounts as you are working in 3 dimensions. When you think you have got it right, undo the nuts, slide the shaft back then pull it forward and the bolts should slide straight in. Learned this trick as my setup can only be put together by sliding the engine down onto the shaft, so it has to be exactly right. Pushing the shaft back does the same thing - but of course you don't have to move the engine.

 

[Caer Urfa]

Do I really need to get someone in to do the alignment on a newly installed beta 35 with a R&D flexible coupling?

Don't mind spending the money really but is it that hard?

Haven't spent too much time on it yet but it didn't take long to get the left/right up/down close, and just lying ontop on the engine seemed to be enough to throw the up/down out a tiny bit.

So if you go for bang on stationary won't the engine be a little out when it's pushing full thrust? (Steel boat so won't change shape between in and out of the water.)

Might have a go at the feeler gauge alignment this afternoon and see how that goes, but is it some black magic art witch only the chosen few can perform?

All thoughts/experience very welcome. Ta

(R&D instructions.. http://www.randdmarine.com/flexiblescinst.asp )

Hope you have also read how to set up the R& D coupling. from my experience not a job I want to do again!

http://www.randdmarine.com/flexiblescinst.asp

 

[GHA]

Hope you have also read how to set up the R& D coupling. from my experience not a job I want to do again!

http://www.randdmarine.com/flexiblescinst.asp

Yup, same link in the first post

 

[Avocet]

I binned mine and knocked up my own out of a pair of Rotoflex "doughnuts". OK, mine's only 12HP, but the engine is visibly misaligned and has been for the past 20 years with no ill efects. The reduction in vibration transmitted through the hull alone made the project worthwhile.

 

[Lon nan Gruagach]

Just done a 6 cylinder IVECO. Dont be put of by the mystical 3 dimension bit, it really is a doddle.

1st get the aiming at the right place as in up/down, left/right ok. Then do the bit with the feeler gauges.
lets say the gap at the top is wider than at the bottom. You need to tilt the engine up (at the front) without moving the back of the gearbox.
Calculate how far the front has to move: take the error to correct and divide by the radius of the flange, multiply that by the distance from the flange to the front mounts, raise them by that amount. Next the rear mounts need to be moved, you can either re-do the up/down bit adjusting them only, or you can do the calculation for them as for the front.

A simplified example: the flange is 4 inches diameter (2 inch radius), the distance from the flange to the front mounts is 3 feet, the rear mounts are just 2 feet aft of the front. the difference in gap is 10 thou.
for the front: (10thou/4inches)*3feet = 120 thou or 0.12 inches.
for the rear: (10thou/4inches)*1foot = 40 thou.

if you know the thread pitch you can count the turns of the nuts.

Probably best to do left/right first since you will might need to slacken bolts enough to use a pinch bar to hoof the engine over.

As for full throttle moving the engine (must be a lot since I can move it by leaning on it) have a good look at the axis of the prop shaft, it will be very close to the plane of the mounts, whereas leaning on the engine you have quite a bit more leverage. Also prop thrust will cause all mounts to deform the same (bend over forwards) resulting in the engine dropping by a really tiny amount while maintaining orientation. of the order of 12 thou.

 

[chrishelen]

It really is a simple job, I have a commercial boat that takes 12 passengers... Recently I changed my engine mounts, re aligned the engine afloat, good explanations above... Some people try to make out it is a black art, but it is simple, the feeler guage gives me a ball park setting, but fully loaded with the boat flexing it is going to change...I know of skippers who allow for this in the initial set up.

 

[GHA]

Just done a 6 cylinder IVECO. Dont be put of by the mystical 3 dimension bit, it really is a doddle. .......

Thanks. I'm feeling much more positive about the whole thing now, ta all.

Might work it out in metric though

 

[Sandy Bottom]

Thanks. I'm feeling much more positive about the whole thing now, ta all.

Might work it out in metric though

1/10th of a mm = +/- 4 Thou :encouragement:

 

[earlybird]

1/100th of a mm = +/- 4 Thou :encouragement:

1/10th of a mm = 4 thou (inch)

 

[Sandy Bottom]

1/10th of a mm = 4 thou (inch)

Oops! Second night on the run that I've done that - I really do need to start wearing those specs!

 

[Neil_Y]

And with the shaft at rest it will be sitting lower than when running, so alignment is never the same when running. But best to get as close as you can.

 

[LittleSister]

How does one know whether the shaft is remaining central in the stern tube? (And how much does it matter?)

e.g. if the gap is at the top, whether to just raise the front mounts by x, or both front by x + y and rear by y?

Otherwise couldn't you have engine and shaft nicely in line, but all set too low (or high) for the stern tube and cutless bearing?

 

[Tranona]

How does one know whether the shaft is remaining central in the stern tube? (And how much does it matter?)

e.g. if the gap is at the top, whether to just raise the front mounts by x, or both front by x + y and rear by y?

Otherwise couldn't you have engine and shaft nicely in line, but all set too low (or high) for the stern tube and cutless bearing?

Make up a temporary sleeve to go round the shaft to keep it central when doing the alignment. If you have a Volvo seal or an inner bearing it should centralise itself.

 

[Sandy Bottom]

How does one know whether the shaft is remaining central in the stern tube? (And how much does it matter?)

e.g. if the gap is at the top, whether to just raise the front mounts by x, or both front by x + y and rear by y?

Otherwise couldn't you have engine and shaft nicely in line, but all set too low (or high) for the stern tube and cutless bearing?

If it's a standard (basic) shaft layout then just turning the shaft by hand as you set it up will usually be good enough by 'feel' - if it's a more complicated set up - say on a commercial hydrofoil with a 35' or 50' long shaft external to the hull then it will mean things like setting up an optical alignment tool from the propellor end and shining it through each cutlass until you reach a 'target' mounted on the gearbox output flange (looks like sighting through a rifle scope). The readings will have to be temperature compensated and sometimes that means doing the alignment at say 5am on consecutive mornings before the sun shines on the hull. Each cutlass will have to be aligned and adjusted as will the engine. The foil will move as the boat lifts out of the water at speed so that will have to be accounted for too. It might take ten days or more to get it spot on.

 

[LittleSister]

Make up a temporary sleeve to go round the shaft to keep it central when doing the alignment.

Thanks, but doesn't that assume the shaft is central to start with?

If it's a standard (basic) shaft layout then just turning the shaft by hand as you set it up will usually be good enough by 'feel'

That's reassuring, and sounds about my level of sophistication.

if it's a more complicated set up - say on a commercial hydrofoil with a 35' or 50' long shaft external to the hull . . . .

Fortunately not - bog standard olde worlde technology of single cutless bearing and conventional stern gland. Shaft is no more than three feet long, I should think.