Need new prop what make and size ?

[RufusR]

I want to replace my flimsey , whining and bent prop next year what make and size is best for my boat ? She is 60 foot Staffordshire with an Isuzu 42 I have read that 18x 12 is about max size I am afraid I am away from boat so have not got current size info to hand but it is a bit of an egg whisk . I have heard crowther are good props and some people wax lyrical about axiom but they seem 2x the price . Also need anti sing according to engineer as current one whines like billy o

 

thanks in advance for your help 

[alan_fincher]

To get any sensible answer you will need to know not just what the engine is, but also what the reduction ratio on the gerabox is.

Without that, anybody would be guessing.

I have heard nothing yet that would ever persuade me that an Axiom is a good idea.  I also believe you can buy a very good prop for a leisure narrowboat without necessariy having to pay Crowther prices.

[RufusR]

Apologies gearbox is prm 150 2:1 

 

[cuthound]

Singing props are usually fixed by grinding tiny bits off the edges of the blades, to brake down the harmonic vibrations which cause the noise.

[RufusR]

Apologies gearbox is prm 150 2:1

 

Sorry don't know why that double posted

[RufusR]

6 minutes ago, cuthound said:

Singing props are usually fixed by grinding tiny bits off the edges of the blades, to brake down the harmonic vibrations which cause the noise.

Yeah the boat yard that is blacking my boat has done that and straightened it but they tell me the prop could do with replacement soon and that I should have a heavier duty "anti sing " one fitted . I am contemplating doing this next year as I get a reduced price at a local dry dock if i book soon so thought I would try to find out what would be best and cost before committing . Can't do it now as not enough time before boat has to be out of dock plus can't really afford it this year on top of blacking etc 

Edited September 5, 2017 by RufusR

[alan_fincher]

Although clearly not specifically for narrow boats, I found the calculations that this prop calculator comes up with very informative.

It's worth entering your boat, engine and gearbox data into it, and seeing what it thinks.

For my two ex working boats, it comes up with numbers very close to what other experts have suggested, and the prop on one that we recently had repitched broadly used their numbers, and people far cleverer than me about such things seem to think we have got it just right.

[MtB]

What size (diameter and pitch) is it now? Can you get the yard to look if it is out being blacked?

Or more particuarly, why do you think the size needs changing?

Looking like a 'bit of an egg whisk' does not necessarily mean it is wrong.

[alan_fincher]

24 minutes ago, RufusR said:

Apologies gearbox is prm 150 2:1 

 

Being pedantic, (and in the big scheme of things I doubt it matters), but I think they are not whole numbers.  Google seems to suggest 2.09 : 1.

[blackrose]

Yes mine is a prm 150 with 2.09: 1 reduction ratio, although I doubt .09 will make much difference to the calculation and results.

Edited September 5, 2017 by blackrose

[RufusR]

That's great thanks Alan will take a look 

19 minutes ago, Mike the Boilerman said:

What size (diameter and pitch) is it now? Can you get the yard to look if it is out being blacked?

Or more particuarly, why do you think the size needs changing?

Looking like a 'bit of an egg whisk' does not necessarily mean it is wrong.

Yeah will ask yard when I phone them thurs dont necessarily think size needs changing just curious as to optimum people keep telling me bigger is better but I have no idea to be honest hence the ask 

[WotEver]

3 minutes ago, RufusR said:

That's great thanks Alan will take a look 

Yeah will ask yard when I phone them thurs dont necessarily think size needs changing just curious as to optimum people keep telling me bigger is better but I have no idea to be honest hence the ask 

When the opportunity arises (like against the flow on a river) are you able to achieve full revs from the engine?

[RufusR]

17 minutes ago, alan_fincher said:

Being pedantic, (and in the big scheme of things I doubt it matters), but I think they are not whole numbers.  Google seems to suggest 2.09 : 1.

Yeah sorry Alan you are probably right but I can only remember what's in my head as manual is on boat and I am 170 miles away I guess I should have kept my powder dry until I got back to boat next week but as I am twiddling thumbs at parents this week have time to post which these days due to work I usuall don't 

[Albion]

1 minute ago, RufusR said:

Yeah sorry Alan you are probably right but I can only remember what's in my head as manual is on boat and I am 170 miles away I guess I should have kept my powder dry until I got back to boat next week but as I am twiddling thumbs at parents this week have time to post which these days due to work I usuall don't 

For a proper cure for prop singing issues take a look at this thread from post 20 onwards. Also shows pictures of the work done on another member's boat and his satisfaction with the result.

https://canalworld.net/forums/index.php?/topic/85747-prop-song/&tab=comments#comment-1912907

Roger

[RufusR]

1 minute ago, WotEver said:

When the opportunity arises (like against the flow on a river) are you able to achieve full revs from the engine?

Never been on a river yet unfortunately awaiting my retirement to be able to go out more that 2 weeks to get to and cruise on river though I guess I could make the nene if I wanted . It seems to rev pretty freely though when pushed to emergency stop etc 

[WotEver]

If it can freely rev then I believe that perceived wisdom is that it could take a somewhat coarser prop but I'll let others that know better than me confirm or contradict this. 

[RufusR]

2 minutes ago, Albion said:

For a proper cure for prop singing issues take a look at this thread from post 20 onwards. Also shows pictures of the work done on another member's boat and his satisfaction with the result.

https://canalworld.net/forums/index.php?/topic/85747-prop-song/&tab=comments#comment-1912907

Roger

Hi Roger 

 

thats good info thanks . If I have to replace prop as suggested is there such a thing as an anti sing prop as the yard suggest ? Rather than having to file off edges of new prop ? 

[Albion]

4 minutes ago, RufusR said:

Hi Roger 

 

thats good info thanks . If I have to replace prop as suggested is there such a thing as an anti sing prop as the yard suggest ? Rather than having to file off edges of new prop ? 

If you can find a prop ready ground down as per the ones supplied by Jooren in Holland then you should be OK but, to be honest, I've never yet heard of UK sourced ones being prepped to eliminate singing so it might be worth interrogating your yard further as to who supplies them and what the treatment is that makes them anti-sing. Even with Jooren one of their props that I received for my barge (I used to carry a spare) and was ready ground still had a slight sing (very slight compared to some that I have heard) so I spent some time (4 hours) with my arm down the weed hatch filing it off some more which totally eliminated the problem. Obviously if the prop is out of the water then an angle grinder will make the job quicker and easier.

I wouldn't worry about having to mod a new prop. Once it has been in use for a while it'll soon pick up some slight edge damage so your filing/grinding efforts will seem negligible damage in comparison.

Roger

[Bee]

Well I think Beta recommend 18 x 12 (needs checking) for their 43 hp with 2:1 reduction so I doubt if it will be far off what you need. As for singing I am told that if the leading edges are sharpened up a bit it stops the singing. I changed to the 18 x 12 from a smaller size and it feels about right, the engine note is now a bit deeper as if it is working harder, no idea if it will reach its full revs as the boat tears along at a hell of a rate and a couple of degrees too much turn on the wheel and I'm in the trees.

[mrsmelly]

3 hours ago, RufusR said:

I want to replace my flimsey , whining and bent prop next year what make and size is best for my boat ? She is 60 foot Staffordshire with an Isuzu 42 I have read that 18x 12 is about max size I am afraid I am away from boat so have not got current size info to hand but it is a bit of an egg whisk . I have heard crowther are good props and some people wax lyrical about axiom but they seem 2x the price . Also need anti sing according to engineer as current one whines like billy o

 

thanks in advance for your help 

You are correct. I have that engine and gearbox set up and a n 18 by 12. I have had it on short boats of 57 foot exactly the same and on this 68 footer and my previous 70 footer all the same and all worked fine. Crowther are good my bro in law has just bought one last year and I use crowther. Bro inlaw did buy and use axiom for a couple of years cos he has loads of money and likes wasting it 

[RufusR]

30 minutes ago, mrsmelly said:

You are correct. I have that engine and gearbox set up and a n 18 by 12. I have had it on short boats of 57 foot exactly the same and on this 68 footer and my previous 70 footer all the same and all worked fine. Crowther are good my bro in law has just bought one last year and I use crowther. Bro inlaw did buy and use axiom for a couple of years cos he has loads of money and likes wasting it 

Good to hear I appear to be on right track . Where do you get crowther props ? From them direct or do they sell through chandlers etc ? Out of interest why did your bro il take off axiom ? Doubt I will ever buy one at the price they are but interested in what they are really like .

[mrsmelly]

Just now, RufusR said:

Good to hear I appear to be on right track . Where do you get crowther props ? From them direct or do they sell through chandlers etc ? Out of interest why did your bro il take off axiom ? Doubt I will ever buy one at the price they are but interested in what they are really like .

Hi

Direct from crowther. Give them a ring a proper old fashioned company with no  cows droppings, they have a website. My bro in law sent me a comprehensive email about his findings of his axiom. I was going to post it on here as a genuine user guide by someone who actualy has owned one rather than the usual crap spoken by people who have never owned one but I havnt a clue how to post it lol. If you wanta read send me your email address and I will send you his email over in its entirety. 

[RufusR]

7 minutes ago, mrsmelly said:

Hi

Direct from crowther. Give them a ring a proper old fashioned company with no  cows droppings, they have a website. My bro in law sent me a comprehensive email about his findings of his axiom. I was going to post it on here as a genuine user guide by someone who actualy has owned one rather than the usual crap spoken by people who have never owned one but I havnt a clue how to post it lol. If you wanta read send me your email address and I will send you his email over in its entirety. 

Thanks email sent 

[mrsmelly]

9 minutes ago, RufusR said:

Thanks email sent 

Did you get mine.......I am a dinosaur 

[RufusR]

3 minutes ago, mrsmelly said:

Did you get mine.......I am a dinosaur 

Yeah got thanks won't post info only