prop shaft coupling???

[boatmike]

That's most helpful. Please see my reply to fisherman. Installers are dead against any sort of flexible coupling as the claim it will allow the engine to flex more. Like I say I have to remain patient....

This is just a load of rollocks. There is no way the shaft coupling should be preventing the engine to flex. If you have over soft mounts and a hard shaft mount you will be over stressing both the back bearing of the gearbox and the shaft itself. As others have said, it is NORMAL to have a flexible coupling and it's not at all good to restrict the movement of a "soft" mounted engine by hanging it on the end of a hard mounted drive flange. I am not sure fitting a flexible coupling will solve your problem but to intimate that it will make matters worse is cretinous.

 

[surekandoo]

That's most helpful. Please see my reply to fisherman. Installers are dead against any sort of flexible coupling as the claim it will allow the engine to flex more. Like I say I have to remain patient....

Not sure they are to blame for this. This is the second new engine installed and was done by local yanmar agent under instruction from E P Barrus. It's probable that the Agent's engineer didn't correctly align things, on the 2nd installation and the original installers didn't check the Agent's work.

The whole thing has been a dog's dinner from start to finish.

I will probably have to appoint a marine engineer and am checking if this will be covered by my boat insurance.

 

[surekandoo]

It is good that they have not washed their hands of it, and are getting better results.

It is also disappointing that they did not align the engine properly when it was installed and does not inspire confidence. As far as rpm is concerned, unless you are achieveing near full rpm you will not be using all the hp of the engine available. In flat water you may get good boat speed, but when the chips are down you will lament the lost rpm and lost hp.

Not sure they are to blame for this. This is the second new engine installed and was done by local yanmar agent under instruction from E P Barrus. It's probable that the Agent's engineer didn't correctly align things, on the 2nd installation and the original installers didn't check the Agent's work.

The whole thing has been a dog's dinner from start to finish.

I will probably have to appoint a marine engineer and am checking if this will be covered by my boat insurance.

 

[pohopetch]

As far as I'm aware, for the Yanmar warranty to be valid the engine must reach its rated RPM under load. There is usually a post installation checklist and sign-off done by the Yanmar agent. In my case the engine (4JH4) "only" got to 3150 RPM when the minimum was 3200 and they would not sign it off and issue the warranty card until the prop was de-pitched by 1/2". I doubt the over propping is anything to do with the vibration, but it should be sorted and sounds like the wrong gearbox was specified.

 

[mtb]

This is just a load of rollocks. There is no way the shaft coupling should be preventing the engine to flex. If you have over soft mounts and a hard shaft mount you will be over stressing both the back bearing of the gearbox and the shaft itself. As others have said, it is NORMAL to have a flexible coupling and it's not at all good to restrict the movement of a "soft" mounted engine by hanging it on the end of a hard mounted drive flange. I am not sure fitting a flexible coupling will solve your problem but to intimate that it will make matters worse is cretinous.

quite right re a flexible coupling, it is the engine that's moving not the coupling ffs
what engine mounts are fitted, are they to soft, have they already caused damage re not fitting the engine correctly ?
if you paid with a credit card or borrowed money your fine
that idea re a shock absorber from the engine to a bulk head is good, I'm thinking of doing it to the 2qm fitted in my colvic. I may go down the inertia route re a weight attached to the end of a rod, my thinking goes it may stabilize the engine without any contact with a bulkhead so no risk of stress

cheers
mick