prop shaft coupling???

[surekandoo]

Is it normal practice to have a completely rigid I.e. metal to metal coupling faces between a 1GM10 gearbox and the prop shaft?

I've just had a new 1GM10 professionally installed & I'm appalled by the racket the whole set up is making. There is no flexible coupling fitted. Should there be?

 

[NormanS]

Is it normal practice to have a completely rigid I.e. metal to metal coupling faces between a 1GM10 gearbox and the prop shaft?

I've just had a new 1GM10 professionally installed & I'm appalled by the racket the whole set up is making. There is no flexible coupling fitted. Should there be?

If the engine is on flexible mounts, it needs at least a flexible coupling. If the engine is rigidly mounted, it won't need a flex coupling.
Which is it?

 

[sailorman]

Is it normal practice to have a completely rigid I.e. metal to metal coupling faces between a 1GM10 gearbox and the prop shaft?

I've just had a new 1GM10 professionally installed & I'm appalled by the racket the whole set up is making. There is no flexible coupling fitted. Should there be?

The 1GM does leap about on tick over & i would have fitted a R & D flexi coupling BUT it would still leap about

 

[Spyro]

The 1gm is a single cylinder so quite a bouncy engine. I have a 2 gm20 and fitted a R & D flexible coupling it removed a bit of resonance I had at certain revs. Definitely much smoother with it fitted. They are not too expensive and very easy to fit.

 

[surekandoo]

If the engine is on flexible mounts, it needs at least a flexible coupling. If the engine is rigidly mounted, it won't need a flex coupling.
Which is it?

The engine is on flexible mounts. The installers say that they never fit a flexible coupling unless there is room to fit a "Plummer block" bearing to take the thrust from the prop. In this case there isn't enough room.

They did say they thought the stern tube may be "a bit tight" !!

I don't understand this. Isn't the stern tube meant to support the propshaft or is it normally just a guide?

 

[Pye_End]

Is it normal practice to have a completely rigid I.e. metal to metal coupling faces between a 1GM10 gearbox and the prop shaft?

I've just had a new 1GM10 professionally installed & I'm appalled by the racket the whole set up is making. There is no flexible coupling fitted. Should there be?

I don't think it is uncommon to find original installations exactly as you describe. My class are like that, and have heard of others. The 1GM10s do jump around and a flexible coupling will only do so much to counter this.

When you say racket, although this installation is far from smooth, there might be other reasons for clonking noises such as engine bouncing on something; bearers bottoming out onto the bead; prop shaft hitting stern tube. Presumably it is 'normal running noise' that you are describing rather than another issue?

 

[sailorman]

The engine is on flexible mounts. The installers say that they never fit a flexible coupling unless there is room to fit a "Plummer block" bearing to take the thrust from the prop. In this case there isn't enough room.

They did say they thought the stern tube may be "a bit tight" !!

I don't understand this. Isn't the stern tube meant to support the propshaft or is it normally just a guide?

the stern tube is there to keep the water out, the stuffing box is then attached by rubber hose to the tube & offers very little support.
does the shaft hit the tube as the engine bounces about

 

[Pye_End]

I don't understand this. Isn't the stern tube meant to support the propshaft or is it normally just a guide?

The shaft is probably supported by a cutless bearing on the outer end of the sterntube, and by the engine. A bit of support from the stern gland, particularly if is a traditional type. If the shaft is too big for the stern tube then clonking between the two could be a source of noise.

 

[surekandoo]

e

the stern tube is there to keep the water out, the stuffing box is then attached by rubber hose to the tube & offers very little support

Ah! So they could be right! I always thought that the bronze stern tube acted as a sort of water lubricated bearing in conjunction with the cutless bearing.

I think the engine may have settled and needs serious realignment. The resonance is shocking even though underside of the cockpit sole is fully sound deadened.

 

[surekandoo]

I don't think it is uncommon to find original installations exactly as you describe. My class are like that, and have heard of others. The 1GM10s do jump around and a flexible coupling will only do so much to counter this.

When you say racket, although this installation is far from smooth, there might be other reasons for clonking noises such as engine bouncing on something; bearers bottoming out onto the bead; prop shaft hitting stern tube. Presumably it is 'normal running noise' that you are describing rather than another issue?

It's a loud rhythmic whirring noise and coupled with excessive exhaust noise makes the current set up a nightmare when motoring. You can't hear the depth alarm, speak on the vhf or be heard from the cockpit when anchoring if the engine's running & in gear!

As far as I can see the engine is not hitting anything and the whirring noise gets worse as the revs increase. The engine itself doesn't seem to move much at mid range revs.

 

[sailorman]

It's a loud rhythmic whirring noise and coupled with excessive exhaust noise makes the current set up a nightmare when motoring. You can't hear the depth alarm, speak on the vhf or be heard from the cockpit when anchoring if the engine's running & in gear!

As far as I can see the engine is not hitting anything and the whirring noise gets worse as the revs increase. The engine itself doesn't seem to move much at mid range revs.

complain the the installer

 

[surekandoo]

complain the the installer

I have done. It's trying to get them to do something that's the problem. I live 2.5,hrs away so it's difficult to get & keep on their case!

To be honest the whole exercise has been a disaster. This is a replacement engine for the 1st new 1gm10 installed in July this year! That was supplied with wrong alternator and wouldn't pick up revs if battery low. Various mods tried by Yanmar agent all of which failed. This engine airfreighted from Japan after "not fit for purpose" wielded at importers E P Barrus.

And that's not the end of the story. Engine will not reach anything like full revs in forward gear irrespective of wind or tide. I reckon gearbox ratio wrong, they think engine under fueled as it's not smoking.

And so it goes on.

Rant over!

 

[NormanS]

There are stern-tubes and there are stern-tubes. The older, (and argueably better) type have the stern-gland rigidly attached to the tube. This gives support to the shaft. Many modern ones have the stern-gland (or seal) hanging on a bit of rubber hose. This gives no support to the shaft. Some would say that best engineering practice would have a rigid shaft, a thrust bearing, then a Halyard type coupling, and the engine on flexible mounts. Many big boats tend to have everything rigid, but then must be lined up accurately.

 

[sailorman]

I have done. It's trying to get them to do something that's the problem. I live 2.5,hrs away so it's difficult to get & keep on their case!

To be honest the whole exercise has been a disaster. This is a replacement engine for the 1st new 1gm10 installed in July this year! That was supplied with wrong alternator and wouldn't pick up revs if battery low. Various mods tried by Yanmar agent all of which failed. This engine airfreighted from Japan after "not fit for purpose" wielded at importers E P Barrus.

And that's not the end of the story. Engine will not reach anything like full revs in forward gear irrespective of wind or tide. I reckon gearbox ratio wrong, they think engine under fueled as it's not smoking.

And so it goes on.

Rant over!

My Son has one in his boat & that was over propped so would not rev up.
i took man inch off of the dia & that cured the problem.
what did you have prior to the first 1GM10 & is the prop original

 

[Pye_End]

And that's not the end of the story. Engine will not reach anything like full revs in forward gear irrespective of wind or tide. I reckon gearbox ratio wrong, they think engine under fueled as it's not smoking.

Just thinking about this, and your whirring noise.

Do you know what prop you are swinging, and what gearbox ratio it is supposed to be? can you turn the prop shaft by hand when not in gear - ie can you check for excess friction in the system after the gearbox?

Have you checked the gearbox oil? When my engine was put in the gearbox was filled to the brim with oil - twice the amount it should have been. After that I checked everything, and came up with one or two other blunders.

Regarding exhaust noise - is there water coming out? What is the exhaust system?

 

[surekandoo]

My Son has one in his boat & that was over propped so would not rev up.
i took man inch off of the dia & that cured the problem.
what did you have prior to the first 1GM10 & is the prop original

It's a 13" x 9 Gori 2 blade folder so can't really be re sized, can it?. This was originally driven by a Vire 12hp 2 stroke. Installers were aware of this, and weight of boat etc.
Propcalc came out with a gearbox ratio of 2.62:1, but installers & engine supplier reckoned the std 2.21:1 would be OK.

Silette Sonic, the Gori importers confirmed 2.62:1 would be what they would have supplied when I contacted them after initial tests indicated the performance shortfall. They are also Yanmar agents.


Like I said a disaster from start to finish. If you pardon the pun this will continue to rumble on!

 

[sailorman]

It's a 13" x 9 Gori 2 blade folder so can't really be re sized, can it?. This was originally driven by a Vire 12hp 2 stroke. Installers were aware of this, and weight of boat etc.
Propcalc came out with a gearbox ratio of 2.62:1, but installers & engine supplier reckoned the std 2.21:1 would be OK.

Silette Sonic, the Gori importers confirmed 2.62:1 would be what they would have supplied when I contacted them after initial tests indicated the performance shortfall. They are also Yanmar agents.


Like I said a disaster from start to finish. If you pardon the pun this will continue to rumble on!

Sons boat also had the Vire & the same prop that was fitted to the Vire. that was over pitched so i could only reduce the dia to get the revs up.
That is i think one of your issues

 

[surekandoo]

Just thinking about this, and your whirring noise.

Do you know what prop you are swinging, and what gearbox ratio it is supposed to be? can you turn the prop shaft by hand when not in gear - ie can you check for excess friction in the system after the gearbox?

Have you checked the gearbox oil? When my engine was put in the gearbox was filled to the brim with oil - twice the amount it should have been. After that I checked everything, and came up with one or two other blunders.

Regarding exhaust noise - is there water coming out? What is the exhaust system?

Wet system & yes water is coming out. Exhaust fitted with std Vetus water lock. There was a muffler non return valve attached to transom exit but installers split it by trying to clamp it's 50mm id down to 45mm exhaust hose! That issue still to be resolved.

Haven't checked gearbox oil level, I confess.

Haven't checked free running of prop shaft but engine runs to 3600rpm in reversed which is Max full load revs, so I can't imagine any problem here.

Please see other post for prop type/size & gear ratio issues.

 

[Pye_End]

Sons boat also had the Vire & the same prop that was fitted to the Vire. that was over pitched so i could only reduce the dia to get the revs up.
That is i think one of your issues

Second this. Pretty sure mine was 2.6:1 with a 12 x 9 (got away with a 13 x 8). With a 2.2:1 this sounds rather over propped, or wrong gearbox. Reduction in reverse is much higher so this makes sense with achieving full revs.

 

[scottie]

It would seem that you may not have the best of installations and would suggest that you get Barrus to check it over

Normal rule of thumb is that if you count mounts coupling and stern gland as three items two may be fieible but not all three although R&D couplings may count as rigid.
Sillette should be able to supply new blades for your prop
Trying to get 50mm to tighten on 45mm does not work