More reflections on our prop issue.

Agree. RH. Nothing wrong with that style of prop. Yes to clockwise from astern, and yes I agree with you gearbox ratio comments.

Regarding installation by 'others' for this sort of thing, from my one experience it is worth double checking everything. Your comments about 'astern and reverse' are very familiar and happened to me! I would also check the gearbox oil, and how well the alignment has been done - does the shaft run free by hand, and is it centred in the stern tube! Do it personally rather than trust anyone else.

Please somebody correct me if I am wrong, but are there two different setting for the gear lever on a Morse controller? - ie check the lever is travelling the correct distance. Not sure if the wrong one would affect the rpm in the way you describe, but I would check it anyway. I presume the 'throttle' is actually being fully opened when you think it is at max rpm?
 
webcraft said:
OK, an update . . .

Tacho is OK, engine produces 3,600rpm+ in neutral, throttle cable travel is OK in and out of gear.

When we initially pushed the throttle lever forard the boat went astern. Miguel did something with the morse control and I thought no more of it.

Now, as I understand it, this was not because the morse control was set up wrong, it was because the prop was the wrong hand so things were set up so ahead was reverse and vice-versa. Apparently this is OK with most modern gearboxes where the ratio in ahead and astern is the same.

- W
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Thinking a bit more about this aspect. You need to check the lever on the box to know which gear you are in. Pretty sure there is a diagram in the manual. It goes up and down and once you know which way is forward and which reverse you know whether the cable has to pull or push to get forward. You can check visually if the engine is running by looking at the shaft - in forward it will turn to the right when in forward. Then set up the control mechanism to suit. There are different holes in the operating levers in the Morse control so that pushing the control lever forward can either push or pull depending on which selects forward at the box end.

Bit tedious to explain but logical once you do it. sounds like Miguel might have got it wrong.
 
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OK, the prop shaft is turning to the right in ahead.

So everything is correct - it is a right hand prop turning to the right in ahead.

It is overpitched to the tune of 1.5" and we are losing 1,000 rpm

The shaft turns freely.

None of this makes any sense.

- W
 
I don’t know if this helps, but when a manager at Lismore passenger ferry commissioned new props, he mistakenly detailed max revs as 1800 instead of 2400. The error was not noticed prior to launching, and at sea trials she was doing close to 4 knots on idle and was completely uncontrollable at close quarters when coming alongside and manoeuvring It puzzles me that you have so much speed on idle and this would suggest that you are over propped.
 
Pye_End said:
Are you absolutely sure it is a 13 x 9.5?
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Well no, I am beginning to have my doubts. 13 x 9.5 was stamped on it, but maybe it has been repitched or messed with in some way.

I wrote down what it said on the prop. 13 x 91/2 and it also said DC2978 - I have no idea what this refers to.

Boat is the water now so I can't measure anything else, there's just the photo.

I think the only thing to do is get the correct prop as recommended by Beta, fit that and see if all is well.

- W
 
Ceejay said:
I don’t know if this helps, but when a manager at Lismore passenger ferry commissioned new props, he mistakenly detailed max revs as 1800 instead of 2400. The error was not noticed prior to launching, and at sea trials she was doing close to 4 knots on idle and was completely uncontrollable at close quarters when coming alongside and manoeuvring It puzzles me that you have so much speed on idle and this would suggest that you are over propped.
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I think the mistake was assuming I knew the pitch of the prop . . . . I copied what was stamped on it onto a piece of paper. (see above). We are doing 2.4kts at idle and 6kts at 2000rpm. With the correct prop I would expect to be doing 5 kts at 2000 rpm and 6 at 2,500.

If the pitch of the prop is accurate I would expect max revs to be around 3,200, not 2,600. (Based on the idea that an inch of pitch increase will reduce revs by about 250rpm)


- W
 
webcraft said:
Well no, I am beginning to have my doubts. 13 x 9.5 was stamped on it, but maybe it has been repitched or messed with in some way.

I wrote down what it said on the prop. 13 x 91/2 and it also said DC2978 - I have no idea what this refers to.

Boat is the water now so I can't measure anything else, there's just the photo.

I think the only thing to do is get the correct prop as recommended by Beta, fit that and see if all is well.

- W
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Ah. Good to read the stamp. At least you know the diameter is correct, and this has the bigger effect. Probably assume that prop is as stamped rather than assume it is wrong, until you can get a chance to check it.

Going back to the Yanmar, can you make a similar evaluation - ie max rpm/gear ratio etc and work out correct prop to see if that all made sense? Ie. did you achieve near max rpm.
 
Pye_End said:
Ah. Good to read the stamp. At least you know the diameter is correct, and this has the bigger effect. Probably assume that prop is as stamped rather than assume it is wrong, until you can get a chance to check it.

Going back to the Yanmar, can you make a similar evaluation - ie max rpm/gear ratio etc and work out correct prop to see if that all made sense? Ie. did you achieve near max rpm.
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I had no rev counter on the Yanmar. 8 x 9.5 is the recommended pitch for the 2GM. I estimate I got 5 knots at around 2,400 rpm, but I can't be sure. I'm getting 6.2 AT 2,000 RPM with the Beta.


- W
 
webcraft said:
Can anyone tell me if this is rh or lh?

View attachment 110655

- W
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That weed won't be making the boat any quicker.
Does the engine smoke or produce black/oily cooling water out of the exhaust?

Is the engine not reaching full rpm because it can't push the load, or because the governor is not asking for full RPM?
That is the fundamental question.

When you select 'full steam ahead' does the throttle lever on the governor actually go as far as it should? As far as it does when you select 'full revs neutral'?

If the engine is overloaded by the prop, there is normally some sign of unburned or partly burned fuel in the exhaust.

Put aside the prop calauclators, they are only a guide. If your hull is draggier than used in the model you will need more power to turn the prop. That drag can be from weed or overloading. Or just not the kind of hull design the modellter was thinking of....


Do a bollard pull test. If the engine revs as fast lahed to the dock as it does under way, then it's probably the governor limiting the speed, not hull drag.

You could check the fuel system. Strangling the fuel flow will have the same effect as throttling back. Either check fuel pressure out of the lift pump at full load, or rig a temporary gravity feed that can be trusted. You could check that fuel use is in keeping with alleged full power at the RPM you are getting.
 
Is the engine as now fitted coupled to a factory supplied gearbox ?
What is the gearbox
have you an installation guide for engine with this gearbox
Whitch way does it suggest you turn the gearbox selector arm for ahead
Is this the way it’s turning at the moment

As I understand the fitter had to alter the control to get the boat to go in the correct direction this does nothing to the gearbox it only changes the selector direction but some gearboxes use different reduction ratios in ahead and reverse which may be your problem
 
the suggested starting point for your engine is 13' x 8'. This suggests to me that 9.5' is a tad course in pitch.1615058840236.png
 
Thanks all.

Bollard pull in ahead only gives 2,300rpm at full throttle.

Engine revs to 3650 or so in neutral. Cable is opening the throttle all the way, to the factory setting.

Engine is brand new, fitted with standard TCM40 gearbox.

Ahead is ahead it turns out, it is a rh prop. The gearbox operating lever on the Yanmar box (Kanzaki) must operate on the reverse sense, I. E down for ahead. The TMC is up for ahead (by deduction, nothing in the manual)

Hull is slippy as a baby's bottom, newly antifouled.

No sign of black smoke even at full throttle opening in gear, but I have not run it for more than a minute like that.

You can watch the throttle as you open it. After it has passed about 60% of its travel further movement does nothing. In neutral throttle response is linear all the way to max revs.

No, a new prop is the only answer. A shame really, as 6.2 kts at 2000 rpm is quite attractive - but we need to be able to punch into wind and sea as well.

Fortunately lockdown means we are booked into here for another 30 days. Once we get the prop we will go up the river to Belém and Joao will fit it in the slings, saving liftout costs.

- W
 
webcraft said:
I had no rev counter on the Yanmar. 8 x 9.5 is the recommended pitch for the 2GM. I estimate I got 5 knots at around 2,400 rpm, but I can't be sure. I'm getting 6.2 AT 2,000 RPM with the Beta.


- W
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Can you be sure that you got your own prop back when they machined the new shaft. Is there a possibility that someone decided that it would be easier to have a metric taper, and use a metric prop that they had lying about the workshop.

Ash
 
webcraft said:
Logic says it must be getting over fuelled, if the throttle keeps opening without the revs increasing.

I haven't run it for more than a minute in the 'overfuelled' condition.

- W
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Logic says if it's overfuelled, then unburned fuel must be going somewhere.
You can test your logic by spending £££ on a new prop and having it fitted and generally going back to square one, or by cheaper, quicker means.
 
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