I have an engine alignment problem in that when my engine was taken
out of the boat in Port Sudan in the Red Sea, the mechanics who were
not marine engineers did not align it properly when they reinstalled
it. At lower revs it vibrates somewhat.

It has four flexi-mounts that are bolted to two longtitudinal engine
bearers and each is connected to the engine by a vertical threaded
bolt.

I would be very grateful if someone in the group could advise me the
sequence or process of aligning it again. The yacht is now out of the
water. The engine is a 37HP Nanni diesel with a "V" drive with a
plastic flexicoupling between the gearbox plate and the propellor
shaft plate.

Thanks
Peter Hendra
N.Z. yacht Herodotus

In article ,
Peter Hendra wrote:

I have an engine alignment problem in that when my engine was taken
out of the boat in Port Sudan in the Red Sea, the mechanics who were
not marine engineers did not align it properly when they reinstalled
it. At lower revs it vibrates somewhat.

It has four flexi-mounts that are bolted to two longtitudinal engine
bearers and each is connected to the engine by a vertical threaded
bolt.

I would be very grateful if someone in the group could advise me the
sequence or process of aligning it again. The yacht is now out of the
water. The engine is a 37HP Nanni diesel with a "V" drive with a
plastic flexicoupling between the gearbox plate and the propellor
shaft plate.

You'll have to wait until the boat's back in the water, the rig is
properly tensioned and things have settled for awhile.

Then it's an iterative process of getting the height and angle closer
and closer, eventually winding up with the shaft in the center of the
shaft log and the drive plate exactly parallel on each axis. Then lock
the mounts down. recheck and bolt the shaft together.

Take the plastic piece out as you measure of course. It'll smooth things
if you're a bit off, but you don't want to have it always flexing.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Jere Lull wrote:
In article ,
Peter Hendra wrote:


I have an engine alignment problem in that when my engine was taken
out of the boat in Port Sudan in the Red Sea, the mechanics who were
not marine engineers did not align it properly when they reinstalled
it. At lower revs it vibrates somewhat.

It has four flexi-mounts that are bolted to two longtitudinal engine
bearers and each is connected to the engine by a vertical threaded
bolt.

I would be very grateful if someone in the group could advise me the
sequence or process of aligning it again. The yacht is now out of the
water. The engine is a 37HP Nanni diesel with a "V" drive with a
plastic flexicoupling between the gearbox plate and the propellor
shaft plate.


You'll have to wait until the boat's back in the water, the rig is
properly tensioned and things have settled for awhile.

Then it's an iterative process of getting the height and angle closer
and closer, eventually winding up with the shaft in the center of the
shaft log and the drive plate exactly parallel on each axis. Then lock
the mounts down. recheck and bolt the shaft together.

Take the plastic piece out as you measure of course. It'll smooth things
if you're a bit off, but you don't want to have it always flexing.


You must align the engine and prop shaft by adjusting the mounts as
above so that the engine and prop shaft are pointing in the same
direction, at the same height and lateral alignment. Additionally,
you need to ensure that the prop shaft is aligned before you align
the engine to it. First, make certain you do not have a bent shaft
or warped prop.

Most prop shafts can be wiggled around somewhat and you need to
ensure that it is true and centered first. Keep in mind that on
many boats the prop shaft and engine is set off to one side by
possibly 1/8 of an inch to compensate for prop walk while proceeding
straight ahead. All inboard propellors will vibrate at some speed,
because of interference between the hull, the flow of water and the
prop.

After it is all set up, next time you yank the engine, consider
unbolting the engine mounts themselves from the engine bed and
pulling the whole works without disturbing the adjustment of the
mounts, still attached to the engine. Worked for me because the
mounts come out and can then be detached from the engine and
reattached with little or no movement using the original holes, etc.

Loose mounting holes, worn from repeated re-installation, are caused
by improperly re-inserting threaded fasteners into holes without
regard for cross threading. A screw should be turned backwards
until the threads are percieved to 'click' into the established
threads. Few workmen bother with this, and holes become sloppy,
requiring filling and re-tapping. Some loose holes may be snugged up
with heli-coils, or by coating the screw with wax and then filling
the hole somewhat with epoxy, and then re-inserting. Improperly
done, this can be a disasater if they need removing in the future.

To assist, you must find or make some reference marks on the boat
and then align the prop shaft and engine to the same spatial
relationship, using the reference marks on the boat and measurements
of the prop shaft and of the transmission shaft, using feeler gauges
between the drive flanges. These are precise measurements to be
sure, and while non too easy, are certainly not impossible.

The alternative is to make adjustments underway, "tuning" the
alignment for minimum vibration. Working around rotating machinery
is very hazardous. You would make the adjustments at the worst
vibrating rpms, taking note of eccentricities, possibly using a
strobe light keyed to the ignition or some mark on the flywheel, or
using a runout gague. Do not do this!

A friend of mine would use the approach of loosening all the
setscrew and then running the ******* hard and fiddling with it
until it settled in or broke, then resetting the screws. I do not
reccommend this, as in about half of the cases it would promptly fly
into pieces. In the other half , it would take longer to fall apart.
Sooner or later, he will lose an arm.

My father in law, God rest his soul, a Canadian veteran of Holland,
an old time horseman, woodsman and a farmer, would buy a bushel of
parts, bolt them together loosely with locking wire, let it shake,
and replace pieces whenever they broke. Many of our farms are run
this way and while farmers survive somehow, there are many
casualties. He is also reputed to have welded a steering knuckle on
his tractor, using the starting battery, a jumper cable and a coat
hangar. It got him home. He was scary in other ways, too.

Good luck.

Terry K

If you are going to tackle this job yourself, you should pick up a
dial indicator gauge and an articulated, adjustable post to use with
it. A magnetic base is convenient for working around engines.

Your engine coupling should have been machined true when the engine
was put together but needs to be checked.

1) Clean up the edges and faces of both coupling halves. Remove all
paint and rust, and get them as smooth as you can.

2) Set up the dial indicator on the edge of the coupling and rotate
the output shaft. There should be only a few thousandths change in
dial reading as the shaft is rotated. If the coupling has a pilot and
you can get the dial indicator to read on the edge, check that as
well. It will be a better reference than outside of the flange but is
tricky to keep the dial indicator on.

3) Set up the indicator on the face of the coupling and rotate. There
should only be a few thousandths change here.

If anything is seriously out of whack here, you should send the engine
and both coupling halves out to be reworked.

4) Calculate the weight of the shaft from the first bearing or
support. Multiply cross sectional area x length x .284 pounds per
cubic inch. Divide by 2. Calculate the weight of the coupling half
the same way and add.

5) Put a wire sling around the shaft as close to the coupling as
possible. Lift with a scale in the line until the reading is as found
in 4). Tie off shaft so scale retains that reading.

6) Put the indicator on the coupling edge, pilot (if any), and face
and check as you did with the engine half. If anything is out of
whack here, you should send the coupling out to be reworked.

7) Be sure the shaft is in the proper fore and aft position. Shim
and adjust the engine until a feeler gauge (spark plug gap gauge works
well) reads the same distance between the coupling faces all the way
around.

8) Put a straight edge across the coupling faces at the 12:00, 2:00,
4:00 etc. clock positions to be sure the centers of the two shafts are
the same. If the edges of the shafts are different sizes, you may
have to use a feeler gauge between a straight edge on the larger one
and the smaller.

9) Bolt and secure the engine mounting bolts.

10) Break for the day. If it's early, take a hike or go swimming.

11) Next day. Recheck all measurements.

12) Bolt up coupling.

This must all be done in the water. On a sailboat, the rig should be
tensioned.

If there is a long distance between the stuffing box and the first
bearing. You should unpack the stuffing box on land, calculate the
shaft weight ignoring the stuffing box as a support point, and hang
the shaft as described in 4) and 5). Then repack the stuffing box.
When the boat is in the water. Recalculate and hang using the
stuffing box as the first support point for the calculation.

Even if you have a flexible coupling, you should get the shaft aligned
as closely as possible. The exception is CV joints which need to have
an intentional angular offset of several degrees for best life.

--

Roger Long



"Peter Hendra" wrote in message
...
I have an engine alignment problem in that when my engine was taken
out of the boat in Port Sudan in the Red Sea, the mechanics who were
not marine engineers did not align it properly when they reinstalled
it. At lower revs it vibrates somewhat.

It has four flexi-mounts that are bolted to two longtitudinal engine
bearers and each is connected to the engine by a vertical threaded
bolt.

I would be very grateful if someone in the group could advise me the
sequence or process of aligning it again. The yacht is now out of
the
water. The engine is a 37HP Nanni diesel with a "V" drive with a
plastic flexicoupling between the gearbox plate and the propellor
shaft plate.

Thanks
Peter Hendra
N.Z. yacht Herodotus

After reading this I'm glad I have saildrives!

Of course,when I snag a pot I wish I had outboards!

Roger Long wrote:
If you are going to tackle this job yourself, you should pick up a
dial indicator gauge and an articulated, adjustable post to use with
it. A magnetic base is convenient for working around engines.

Your engine coupling should have been machined true when the engine
was put together but needs to be checked.

1) Clean up the edges and faces of both coupling halves. Remove all
paint and rust, and get them as smooth as you can.

2) Set up the dial indicator on the edge of the coupling and rotate
the output shaft. There should be only a few thousandths change in
dial reading as the shaft is rotated. If the coupling has a pilot and
you can get the dial indicator to read on the edge, check that as
well. It will be a better reference than outside of the flange but is
tricky to keep the dial indicator on.

3) Set up the indicator on the face of the coupling and rotate. There
should only be a few thousandths change here.

If anything is seriously out of whack here, you should send the engine
and both coupling halves out to be reworked.

4) Calculate the weight of the shaft from the first bearing or
support. Multiply cross sectional area x length x .284 pounds per
cubic inch. Divide by 2. Calculate the weight of the coupling half
the same way and add.

5) Put a wire sling around the shaft as close to the coupling as
possible. Lift with a scale in the line until the reading is as found
in 4). Tie off shaft so scale retains that reading.

6) Put the indicator on the coupling edge, pilot (if any), and face
and check as you did with the engine half. If anything is out of
whack here, you should send the coupling out to be reworked.

7) Be sure the shaft is in the proper fore and aft position. Shim
and adjust the engine until a feeler gauge (spark plug gap gauge works
well) reads the same distance between the coupling faces all the way
around.

8) Put a straight edge across the coupling faces at the 12:00, 2:00,
4:00 etc. clock positions to be sure the centers of the two shafts are
the same. If the edges of the shafts are different sizes, you may
have to use a feeler gauge between a straight edge on the larger one
and the smaller.

9) Bolt and secure the engine mounting bolts.

10) Break for the day. If it's early, take a hike or go swimming.

11) Next day. Recheck all measurements.

12) Bolt up coupling.

This must all be done in the water. On a sailboat, the rig should be
tensioned.

If there is a long distance between the stuffing box and the first
bearing. You should unpack the stuffing box on land, calculate the
shaft weight ignoring the stuffing box as a support point, and hang
the shaft as described in 4) and 5). Then repack the stuffing box.
When the boat is in the water. Recalculate and hang using the
stuffing box as the first support point for the calculation.

Even if you have a flexible coupling, you should get the shaft aligned
as closely as possible. The exception is CV joints which need to have
an intentional angular offset of several degrees for best life.

Hi Peter

We overhauled the gearbox and replaced the engine mounts on "Leonidas"
last year. This included the realigning of the engine mounts. We found
the process easier than suggested by Jere, Terry, Roger and Jeff.

We have engine mounts that are screw adjustable, and the front mounts
are at 45 degrees so that there is a small amount of latteral movement.
All are screw type adjustable like you have, and we also have a flexible
'Vetus' coupling on the propellor shaft. Because the coupling pad is
soft, you have to remove it while you do the alignment, and align the
metal to metal coupling surfaces.

We did the initial aligning on the hard, (we had to get the yacht back to
the marina on relaunching) and then realigned it in the water two weeks
later.

The process is as follows :

* remove flexible coupling pad and loosely screw metal coupling flanges
together. Prop shaft will slide both ways so you can remove the pad and
then couple the metal flanges together.

* With texture color mark four equally spaced reference points on the
flange. ie 90 degrees apart.

* With feeler gauges measure gap at each reference point and write
down the results. (This is important as you can see the results of each
adjustant, and it greatly shortens the process.)

* Think about ajjustment to be made and then turn one adjusting screw
one half a turn. Measure with feeler gauges and write down results.

* Continue untill you get same result on the feeler gauge at each
measuring point. (or within 3 thousandths of an inch.

* Tighten locking nuts on engine mounts, recheck with feeler gauges.
(Repeat if necessary). If OK reinsert flexible pad.

* After launching and vessel has settled down, then remove flexible
pad and recheck alignment.
Adjust if necessary, and refix pad.

We got Leonidas within 2 thou' on the hard, but she was about 11 thou out
when we rechecked her after she'd been in the water for two weeks.
Realignment took about five minutes plus another fifteen minutes each to
remove and reinsert the flexible coupling as the bolts were not easy to
reach.

Re- reading above, I think it was easier to do than explain. Its not a
difficult job. The only tools you will need are spanners, feeler gauge
set and a good light.

Fair winds

Graeme
sv "Leonidas"

One word about the plastic flexicoupling they are not designed to correct
alignment.
All the powertrain has to be correctly aligned first. Before you do anything
check the cutlass bearing and the strut. If the cutlass bearing is loose
and the strut out of line, bent or not anchored properly these have to be
fixed using the proper sequence.
After years of misalignment on my boat and countless attempt to correct it
we used the following method:
With the boat out of the water the engine was taking out. The shaft was
removed. It was inspected. The shaft was found to be gouged by the set
screws inside the flange connecting it to the engine. This had for effect
to make alignment near impossible.
A new shaft was used. The connecting flange was properly mounted and
secured with the set screws on the new shaft with the proper key stock. The
shaft and the flange were set up on a lathe. Then the flange was machined
perpendicular to the shaft. After that the shaft with the flange already
mounted were pushed through the hull. Then the engine was installed in line
with the flange and the mountings adjusted.
After having the fiberglass boat in the water for about two weeks the
alignment was checked and minimum correction done.
In my opinion, it is best to have the shaft and flange machined together.
While you are at it you be rewarded to check the cutlass bearing and strut.
In extreme case you may have to replace the cutlass bearing and rectify and
strengthen the base of the strut. If you detect an hairline crack in the
strut welded repair is not recommended. Replacing with a new one is much
better.

"Graeme Cook" wrote in message
...
Hi Peter

We overhauled the gearbox and replaced the engine mounts on "Leonidas"
last year. This included the realigning of the engine mounts. We found
the process easier than suggested by Jere, Terry, Roger and Jeff.

We have engine mounts that are screw adjustable, and the front mounts
are at 45 degrees so that there is a small amount of latteral movement.
All are screw type adjustable like you have, and we also have a flexible
'Vetus' coupling on the propellor shaft. Because the coupling pad is
soft, you have to remove it while you do the alignment, and align the
metal to metal coupling surfaces.

We did the initial aligning on the hard, (we had to get the yacht back to
the marina on relaunching) and then realigned it in the water two weeks
later.

The process is as follows :

* remove flexible coupling pad and loosely screw metal coupling flanges
together. Prop shaft will slide both ways so you can remove the pad and
then couple the metal flanges together.

* With texture color mark four equally spaced reference points on the
flange. ie 90 degrees apart.

* With feeler gauges measure gap at each reference point and write
down the results. (This is important as you can see the results of each
adjustant, and it greatly shortens the process.)

* Think about ajjustment to be made and then turn one adjusting screw
one half a turn. Measure with feeler gauges and write down results.

* Continue untill you get same result on the feeler gauge at each
measuring point. (or within 3 thousandths of an inch.

* Tighten locking nuts on engine mounts, recheck with feeler gauges.
(Repeat if necessary). If OK reinsert flexible pad.

* After launching and vessel has settled down, then remove flexible
pad and recheck alignment.
Adjust if necessary, and refix pad.

We got Leonidas within 2 thou' on the hard, but she was about 11 thou out
when we rechecked her after she'd been in the water for two weeks.
Realignment took about five minutes plus another fifteen minutes each to
remove and reinsert the flexible coupling as the bolts were not easy to
reach.

Re- reading above, I think it was easier to do than explain. Its not a
difficult job. The only tools you will need are spanners, feeler gauge
set and a good light.

Fair winds

Graeme
sv "Leonidas"