Corniche vibrate alot

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IsmoS

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Hi all,

good tips are now valuable.

Corniche with 2xTAMD 41A shafts (Ex. VolvoPaul, "Ceres").
Starboard side vibrate a lot when fast run. 3000...3800 rpm (18...26knots).
750...1700rpm / 4...7,5 knots no vibration noticeable. Also no vibrate with neutral gear and high revs.
Vibaration was and is so hard that engine mounts was broken up and axel bearings loose. Vibration feels all over the boat and is like wavy. Increasing and decreacing all the time. Port side run is smooth.

Propellers are renovated and balanced by professional.
Shafts are ok. Checked with lathe by professional.
New shafts bearings.
New Flexible Coupling (A.S.A.P Supplies, part nro 807109)
New gearbox (MS4A) oil , no pieces of metal founded. Gears works fine.
Shaft and gearbox is in line. Less than 0,05mm.
New engine mounts.
Nozzles are chekked. "No as good as they can be but good enought" (sayed by diesel engineer). Opening pressures was all the same (12 pieces).
All filters are new.
Fuel lines are ok by visualy and leaks not founded.

Still vibrate alot... can not understand anymore. Need help, please.

Could the problem be in the fuel supply? Feed pump timing or transfer pump?
What happen if feed pump timing not work as it shoult work?
Or if transfer pump do not produce sufficient pressure or volume.
Or something else?
Any ideas or experience?

Thx for any advance.

Ismo
 
I think Portofino is on the right track
I came across a similar problem some years ago
Volvo's but smaller
The 'after'crank seal was leaking a dribble but that lead me to diagnose that the crankshaft had actually been worn (a groove where the seal sat) plus the flywheel on that engine had shed a tooth or two !
Most unusual and to this day I don't know why
As Porto says something internal is throwing a wobbler
Get the oil analysed on both motors to see if there is any difference between them
This may or may not help by the way but I reckon it's worth a try
 
I had a stubborn vibration on the port side on my previous boat, a Phantom 38 with TAMD 63Ps. It turned out to be a bent shaft. I had the shafts checked by a professional shop who concluded that shafts are ok and within tolerances. There was a 0,2 mm bend on the port side measured between the bearing points but still they said that 0,2 mm would not cause the problem. The starbord shaft was less than 0,1mm off at the center. At cruising speed the port engine was shaking noticeably even if everything was suppose to be spot on. The following winter I removed the shaft and rigged a shaft measuring setup in my garage. Indeed there was a 0,2 mm bend at the mid point. I also noticed that the shaft was very elastic and bent easily much more than the 0.2 mm when pressing by hand. This must result in a situation where the centrifugal foces amplifies a small bend at speed. I then straightened the shaft to less than 0,1mm by applying pressure on it for several days. This resoved the vibe problem and the boat was smooth as ever.
 
baylabayla3288 said:
I had a stubborn vibration on the port side on my previous boat, a Phantom 38 with TAMD 63Ps. It turned out to be a bent shaft. I had the shafts checked by a professional shop who concluded that shafts are ok and within tolerances. There was a 0,2 mm bend on the port side measured between the bearing points but still they said that 0,2 mm would not cause the problem. The starbord shaft was less than 0,1mm off at the center. At cruising speed the port engine was shaking noticeably even if everything was suppose to be spot on. The following winter I removed the shaft and rigged a shaft measuring setup in my garage. Indeed there was a 0,2 mm bend at the mid point. I also noticed that the shaft was very elastic and bent easily much more than the 0.2 mm when pressing by hand. This must result in a situation where the centrifugal foces amplifies a small bend at speed. I then straightened the shaft to less than 0,1mm by applying pressure on it for several days. This resoved the vibe problem and the boat was smooth as ever.
Click to expand...

Reckons to have his shafts " checked professionally on a lathe"
Well that's what deduced from post # 1
 
Extra weight ( mass ) of the spinning stuff that happens to be attached - amplifies the prob .
Spinning stuff attached has been checked .
Presumably some paperwork to back up this from each " professional "
 
I would not take the statement "shafts are ok" for granted if it continues to vibrate. Builders seems to use the thinnest possible shaft dimensions which narrows down the tolerances as I found out in my case. If your boat is in the water you can still verify the straightness of the shaft quite easily by checking the engine/ gearbox movements at stand still with a dial indicator. Attach the indicator to the shaft clamp at the gear box, then rotate the shaft 90 degrees at the time and take note of the readings, do the same for the non vibrating engine and compare. Your boat probably has two shaft bearings, one at the upper end next to the shaft tube (if not you can ignore this procedure). If your shaft is bent you will see movements of the engine between different rotation angles. The shaft is virtually wipping the engine around with increased amplitude the higher the rpms.
 
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The vibration is obviously a rotational issue from the drivetrain , is the engine aligned to the shaft ?

As you have had the shaft out Is the coupling fitted to the shaft correctly, is the prop fitted to the shaft correctly.

The flywheel drive plate can break up it could be that .
 
Also no vibrate with neutral gear and high revs.
Click to expand...
Would have thought if engine mechanical woes,other clues such as low oil pressure/leaks and even audiable noise would be present.

Still sounds like stern gear . Despite experts opinion on individual components would still suspect shafts/Props/ "P" brackets or cutlass bearings.
Boats needs to be out of water and entire system visually checked in situ. ?

If these vibrations appeared without any previous history would instantly diagnose builders bag/safety netting/rope or just about everthing thing else my props have "collected" over the years.
Murv even managed a shopping trolley last year.
 
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Thank you for all the activity. Lot of good ideas.
We did lot of research and measurements and sea trials in last days.

And we finded something.

We belive that there is/was two different source of vibration.
I install new fuel pump. The hull and engine "Wavy" vibration disappeared. Litle bit hard to understand that but We ponder that mayby fuel pump did not produced enough pressure or volume of fuel to feed pump at high revs (when maximum power was needed).
We also assume that two different vibs sourses can cause some sort of amplitude which broked up the engine mounts.

Continuous vib is still. Right now I think that continuous vibration must come from shafts.

VolvoPaul, Engine is aligned to the shaft. Measured cap in Flexible coupling measuring point (red bolt) is 0,05mm.
Shaft it self has 0,1mm swing to the hull. Measured inside boat near to coupling.
I think that prop fitted as it should be fit. It gets a special attention when installed.

I have "Balancing report" for props and for that reason my next suspicion is now shaft it self, as baylabayla3288 has also had problem with.
Also I have only f2f discourse with engineer how check the shafts (no documet of measurements).
Unfortunately I do not want to lift the boat out of water so shafts re-check will remain in the autumn. This summer we will sail max 7,5 knots.

Ismo
 
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