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Hi, I have a 60ft Norton canes with a 2lw. The prop size is 22 x 22 and I think it is over propped. I have had the boat from new and it has never revved over 950. This is even on deep rivers. As I have once again bent the prop so its maybe time to try a different size, may be 22 x 20 if there is such an animal. Any body else gone this route. Will the change be to drastic? Any help will be great fully received. 

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If it is 2:1, and the current prop is 3 blade with a typical blade area, I would have thought the engine would easily handle your current 22" x 22"

Putting some guessed numbers about your boat and engine into the Vicprop calculator I have used successfully in the past actually suggests around 25" x 21", so that would actually suggest 22" x 22" might be under-propped.

Try putting your own numbers into Vicprop.  I guessed a draught and weight for your boat, so try it with your best guess at actual numbers, and see what it suggests.

Caveat:  Vicprop clearly is clearly not specifically about narrow boats, but numbers I have got from it align well with sizings that companies like Crowthers or FAL come up with.  It has worked well for us.

You can have just about any size propeller you like.  If you have 22" x 22" it can be re-pitched larger or smaller by a specilaist.  You would not normally need to replace it, but I note you say it s damaged.  They can also repair quite badly damaged props in some circumstances, I think.

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Yes, I have just inputed the info and it comes out as you say. But it's definitely over propped. Well it won't rev out. Its been like this from walshes. Runs fine, no smoke, starts first turn from cold. The injector pump was serviced and recalibrated 4 or five years ago with no change to the max revs achieved in gear. I have got to try a different prop ratio just don't know what to try. 

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I only have a 'fug-stirrer' in my boat, thus expect to have to spin the engine somewhat to 'go fast' - but I would like not to....

 

However isn't the 'joy' of a 'proper' engine that it whistles along its way with the engine just turning slowly?? Everything revolving at a human speed??

If you get clouds of black smoke when you try to increase the revs - then you perhaps play with the transmission. If not, then it's as The Good Lord intended.....

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Oh yes, no problem with that. Revs to max out of gear. Exhaust clean as a whistle. 

Edited by Wrinkley
Clarity

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Agreed old goat but when the tide turns on the upper Trent and you struggle to make forward progress a few more revs would ease the situation. 

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9 minutes ago, Wrinkley said:

Agreed old goat but when the tide turns on the upper Trent and you struggle to make forward progress a few more revs would ease the situation. 

There is your problem - there is no tide on the upper-Trent.

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Whilst I have no experience with anything that has as low maximum RPM as your Gardner, I still think something sounds wrong here.

I now have two boats with a Lister HA2 in each.  OK, on the face of it a very different engine, but hear me out.....

What s your Gardner rated at?  24HP or thereabouts?  If so, thats not far removed from my Listers at 22HP.

And maximum design revs?  1,200RPM, possibly?  My Listers are 1,800RPM max, so 1.5 times the Gardner?

But I have 3:1 reductions on each, and you have 2:1 reduction, so I'm thinking each potentially turn the prop at a maximum of 600RPM, with similar power available.

So, in theory, my props shouldn't be a disaster if used with your engine.

Flamingo has 25 1/4" x 21"

Sickle has 26" x 19.4"

(Both of these are from memory, but I think I'm correct).

So if you are over-propped on 22" x 22", I would expect you to be far more so if you substituted either of my propellers, even though either work well with my 600 RPM maximum shaft speed, (same as yours?) and my 22HP (less than yours?).

So what am I missing?  22" x 22" doesn't sound over-propped to me.

 

However I suspect several forum members will have a similar engine on a 2:1 box, so it could be interesting to hear what they have.

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Its all a black art and a mystery to me. I have tried to generate some plots of prop law, and get the torque curves of various vintage engines. I did this with a view to maybe replacing my JD3 with a more proper engine one day. Things just don't tally with what a lot of people say on this forum about their props, unless most of them either exaggerate or like to overprop their boats.

 

We have a 21 by 20 and thats just about right, we get to maybe 1300 rpm on deep water if the engine is nicely warmed up, maybe even 1400 if things are really going well. The JD3 claims to produce 180 to 190Nm at 1400 (depending on which spec sheet I look at). The 2LW claims to produce about 155Nm at 1400, but I think there are various "builds" and I don't know how accurate the torque curves are for old engines. Based on these figures 22x22 is a bit big.

 

I reckon 21x20 on your engine would get you to about 1200rpm. How fast do you want the engine to go?, and is your boat speed at tickover currently ok? 

 

I believe that the various prop calculators are not really applicable to narrowboats.

 

..............Dave

 

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15 minutes ago, alan_fincher said:

Whilst I have no experience with anything that has as low maximum RPM as your Gardner, I still think something sounds wrong here.

I now have two boats with a Lister HA2 in each.  OK, on the face of it a very different engine, but hear me out.....

What s your Gardner rated at?  24HP or thereabouts?  If so, thats not far removed from my Listers at 22HP.

And maximum design revs?  1,200RPM, possibly?  My Listers are 1,800RPM max, so 1.5 times the Gardner?

But I have 3:1 reductions on each, and you have 2:1 reduction, so I'm thinking each potentially turn the prop at a maximum of 600RPM, with similar power available.

So, in theory, my props shouldn't be a disaster if used with your engine.

Flamingo has 25 1/4" x 21"

Sickle has 26" x 19.4"

(Both of these are from memory, but I think I'm correct).

So if you are over-propped on 22" x 22", I would expect you to be far more so if you substituted either of my propellers, even though either work well with my 600 RPM maximum shaft speed, (same as yours?) and my 22HP (less than yours?).

So what am I missing?  22" x 22" doesn't sound over-propped to me.

 

However I suspect several forum members will have a similar engine on a 2:1 box, so it could be interesting to hear what they have.

So this is a good example of why I can't make 100% sense of these things.

You are driving a big 26x19.4 prop to about 600rpm using 22 horsepower,   I can only drive a much smaller 21x20 to 600-700 rpm but have maybe 35Hp available.

 

..........Dave

 

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The obvious conclusion is that you *don't* have 35hp available...

 

Just because the engine will reach maximum revs out of gear doesn't mean it will reach rated power, because there's no load on it. Maybe you have a partially blocked fuel supply somewhere which limits fuel flow and maximum power?

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47 minutes ago, IanD said:

The obvious conclusion is that you *don't* have 35hp available...

 

Just because the engine will reach maximum revs out of gear doesn't mean it will reach rated power, because there's no load on it. Maybe you have a partially blocked fuel supply somewhere which limits fuel flow and maximum power?

Or incorrectly set injection pump? 

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1 minute ago, jonesthenuke said:

Or incorrectly set injection pump? 

The engine specs from both Beta and John Deere suggest about 35Hp at 1400 rpm or something like that, Beta suggest a prop of about 21x20 (I think 20x20?),   the engine gets to its suggested maximum revs under load, and is just getting into the "black smoke" regime at maximum revs, so I see no reason to suspect anything is wrong. Ive actually owned two separate JD3's and had the injection pump rebuilt and recalibrated in the past, and all behave in much the same way, so I am pretty happy that everything is in order. Its probably more likely that some older engines produce more power than their spec suggests, but I don't think this is the case. I would love to get hold of some "power or torque vs speed" curves for various props but its not easy to find this data.

 

.................Dave

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On 11/10/2018 at 19:39, Wrinkley said:

Yes, I have just inputed the info and it comes out as you say. But it's definitely over propped. Well it won't rev out. Its been like this from walshes. Runs fine, no smoke, starts first turn from cold. The injector pump was serviced and recalibrated 4 or five years ago with no change to the max revs achieved in gear. I have got to try a different prop ratio just don't know what to try. 

Not even a hint of blackness to full throttle?

 

Even if your pump was recalibrated I do wonder if there is enough fuel?

 

The consensus seems your engine isn't providing the expected output power.

 

I'm wondering if its worth measuring fuel flow rate and with an accurate knowledge of the maintained revs you could check actual fuel usage with expected.

 

How is the rev counter driven? Is it from the alternator? Are you confident the pulley sizing is correct? You can get cheap optical tachometers on eBay to check.

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Well tried that "the  fuel rack "slider bar" is moving fully to the right and is up against the fuel limiting trigger at full load. I.e with the engine at full load, try and pull the the fuel rack outwards, to your right. " so still thinking the load is too much for the power produced. More power or reduced load. As the prop needs attention got to try and have adjusted to less than the 22 x 22 it's supposed to be. Any body got a 22 x 20 1.5 laying about I could have a go with? 

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4 minutes ago, Mikexx said:

Not even a hint of blackness to full throttle?

 

Even if your pump was recalibrated I do wonder if there is enough fuel?

 

The consensus seems your engine isn't providing the expected output power.

 

I'm wondering if its worth measuring fuel flow rate and with an accurate knowledge of the maintained revs you could check actual fuel usage with expected.

 

How is the rev counter driven? Is it from the alternator? Are you confident the pulley sizing is correct? You can get cheap optical tachometers on eBay to check.

Thanks for you comments, I'll try and go through them. Exhaust is just about clear on full throttle, had a bmc 1800 before and that gave black smoke on full wack. I have no way to measure fuel usage other than the average use between tank refills is constant over the eight years from "new". On full throttle there is still fuel running back to the tank indicating, to me, plenty of fuel available to the pump. Rev counter is a cycle speedo fitted to the engine belt pulley which matches the alternator hz output. Sounds a bit rubbish but it works well. Tick over 400rmp, flat out just over 1200, the plate on the injector pump says max 1300. The prop I have is bent and needs repairing just trying to work out what to have it set to. My thinking is 22 x 21. The 22 x 22 is fine on the canals I would just like a bit more power/revs on the occasional river and tidal bits we use. 

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4 minutes ago, Wrinkley said:

Tick over 400rmp, flat out just over 1200

 

Makes me question the accuracy of your rev counter. I suggest checking against another instrument.

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I asked that back in post 13 and got no answer. I don't understand the reference to alternator frequency if its a belt drive.

Edited by Boater Sam
smellings

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Apologies Boater Sam for not replying earlier. I don't think that belt slip is a big issue with my set up. I have two 13.5mm belts on the alternator. The readings from both ways I have of measuring rpm do not differ significantly from each other whether the output from the alternator is 20 or 120amps. I would have thought that if belt slip was occurring the difference between the 'rev counters' as the load on the alternator increased would change. I am reasonable sure that most of the claimed 28 horses in 1953 for my engine are still at home and available. 

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Got it, you have a mechanical rev counter running on the alternator belt and a frequency counter on the alternator stator winding. Both driven by belts.

But is the pulley ratio alternator to crank correct? It is very difficult to accurately establish effective belt pulley sizes .

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