Axiom - Oh Dear...

[matty40s]

Customer is swapping his Crowther for an Axiom to improve his stopping distance with a 70ft narrowboat and gave the specific dimensions from the boats original prop to Axiom.

On docking this morning and removing the old prop , something appeared not quite right!!!

 

 

back to Axiom it goes...

 

The existing is a 24x 20 pitch - looks like the replacement is a 20 x 24.

 

Alan, I will ask him what he is doing with the old prop if you are interested although I think its a 1 1/2 tapered shaft fit.

[Alan de Enfield]

 

On docking this morning and removing the old prop , something appeared not quite right!!!

 

 

 

Doh - its obvious what's wrong - they have supplied a silver one instead of a black one.

[billS]

Are you sure the new one isn't intentionally smaller as it may require the additional space below the uxter plate to allow the magic to work?

[mrsmelly]

My bro in law swopped his axiom to a crowther a couple of weeks or so ago. Strange world innitt.

 

Tim

[Paul C]

[MtB]

My bro in law swopped his axiom to a crowther a couple of weeks or so ago. Strange world innitt.

 

Tim

 

 

I'll give him 50p for the old Axiom...

[WotEver]

 

 

I'll give him 50p for the old Axiom...

I'll advance that to 40p. Better sell quickly...

[Dalslandia]

Propeller design is a dark art, sorry black magic it is, guessing works too

[alan_fincher]

Alan, I will ask him what he is doing with the old prop if you are interested although I think its a 1 1/2 tapered shaft fit.

 

Looks like a Right Hand prop to me. Both my boats have Left Hand props.

 

(Assuming the comment was directed at me).

[matty40s]

 

Looks like a Right Hand prop to me. Both my boats have Left Hand props.

 

(Assuming the comment was directed at me).

Yes it was - and I think you are correct, never mind, will keep my eyes out for one

[PaulG]

 

 

I'll give him 50p for the old Axiom...

Excessive, IMHO.

The boat opposite me has an Axiom. The owner says that they spend a lot of time down the weed hatch...

[matty40s]

Excessive, IMHO.

The boat opposite me has an Axiom. The owner says that they spend a lot of time down the weed hatch...

My prop spends all its time down the weedhatch.

[GUMPY]

But its an Axiom of course it will be better than any other prop even if they size it wrong

 

 

https://runtontorun.files.wordpress.com/2015/04/shitebag.jpg

Edited November 7, 2016 by Loddon

[Murflynn]

Customer is swapping his Crowther for an Axiom to improve his stopping distance with a 70ft narrowboat and gave the specific dimensions from the boats original prop to Axiom.

 

less blade area, smaller diameter.

 

will certainly improve the stopping distance - it will probably double it.

[mrsmelly]

I'll advance that to 40p. Better sell quickly...

 

He aint selling it as he aint skint ( not even nearly ) and he is keeping it as a spare in case he trashes the new crowther. I too keep a spare prop now having trashed one last year and bought a new one. He liked his axiom but obviously not enough He can of course speak from experience genuinely unlike most of us who have never had or even been on a boat with one fitted.

 

Tim

[ditchcrawler]

 

He aint selling it as he aint skint ( not even nearly ) and he is keeping it as a spare in case he trashes the new crowther. I too keep a spare prop now having trashed one last year and bought a new one. He liked his axiom but obviously not enough He can of course speak from experience genuinely unlike most of us who have never had or even been on a boat with one fitted.

 

Tim

Sue on Retirment NoProblem had one fitted and had it taken off again, there other posts about it as well if you want to go through the blogs in that time to read them.

 

http://noproblem.org.uk/blog/mr-axiom-tests-his-prop-and-what-a-thief/

 

http://noproblem.org.uk/blog/the-spring-cruise-continuous-at-last/

[nikvah]

I have an axiom prop on my current boat and hardly ever have to clear it via the weed hatch even travelling thro' Leamington and BCN backwaters, as I do. I find a burst of reverse will usually clear any weeds or plastic and even the odd bit of clothing can be seen swirling out from below. Fewer visits down the hatch than on my previous boat anyway, which had a normal prop.

[mrsmelly]

I have an axiom prop on my current boat and hardly ever have to clear it via the weed hatch even travelling thro' Leamington and BCN backwaters, as I do. I find a burst of reverse will usually clear any weeds or plastic and even the odd bit of clothing can be seen swirling out from below. Fewer visits down the hatch than on my previous boat anyway, which had a normal prop.

 

The bro in law liked his and said it deffo stopped the boat well BUT it didnt go too well. He has loadsa wonga so buys whatever he feels like, his boats are always kept immaculate.

 

Tim

[MtB]

 

The bro in law liked his and said it deffo stopped the boat well BUT it didnt go too well. He has loadsa wonga so buys whatever he feels like, his boats are always kept immaculate.

 

Tim

 

 

This is to be expected. Ordinary blades are optimised for ahead performance. By definition this means they will bite less well in astern than a forward/astern symmetrical blade, optimised for neither, as the Axiom looks to my amateur eye.

 

Put another way, the Axiom stops well at the expense of forward grip.

[alan_fincher]

I've said it before but it is very interesting that an Axiom supplied now looks entirely different to what they looked like when first launched.

 

Rather clever of them to have come up with the perfect design, only to apparently completely scrap it, and come up with an entirely different perfect design.

[MtB]

I've said it before but it is very interesting that an Axiom supplied now looks entirely different to what they looked like when first launched.

 

Rather clever of them to have come up with the perfect design, only to apparently completely scrap it, and come up with an entirely different perfect design.

 

Eventually I expect they'll refine it further and arrive at the standard 'micky mouse ear' design, then claim everyone is copying them!

[Murflynn]

I've said it before but it is very interesting that an Axiom supplied now looks entirely different to what they looked like when first launched.

 

Rather clever of them to have come up with the perfect design, only to apparently completely scrap it, and come up with an entirely different perfect design.

you have to hand it to them - they are very inventive, imaginative and ................

 

 

.................... nuff said.

[Dalslandia]

 

Eventually I expect they'll refine it further and arrive at the standard 'micky mouse ear' design, then claim everyone is copying them!

Maybe it is the reason they are shaped like they are, no one will copy them.

[PaulG]

I've said it before but it is very interesting that an Axiom supplied now looks entirely different to what they looked like when first launched.

 

Rather clever of them to have come up with the perfect design, only to apparently completely scrap it, and come up with an entirely different perfect design.

Any propellor design is a compromise. If you improve one aspect of it's performance, then it will often be to the detriment of another.

Propellor design has been studied in great detail, and over a very long period. Even in the very early days, Brunel was responsible for two years of tests between 1843 and 1845 using HMS Rattler and other vessels.

Since then, designs have been developed for many specialised applications e.g. submarines (primarily for quiet running), large merchant vessels (primarily for efficiency).

In more recent years, powerful computing systems have been developed to produce optimised designs.

 

Axiom claim that their design is beneficial for "Suitable for most types of vessel - fast or slow, displacement or semi displacement".

 

So Axiom claim to have come up with a kind of "universal design" that over 100 years of research by heavy hitters like the Admiralty has missed.

Personally I do not believe it.

 

There's a discussion of ship propellor design here:

http://www.marineinsight.com/naval-architecture/10-factors-considered-efficient-ship-propeller-design/

and in more detail here:

http://marine.man.eu/docs/librariesprovider6/propeller-aftship/hydrodynamics.pdf?sfvrsn=2

 

There are blade profiles in the second document that appear very similar to the Axiom one...

Yes, they are large ship propellors, but the performance must be proportional to size or they would not be tested on models.

I am not suggesting that their design is not a good one - it may be perfectly sound, but I don't believe their "all things to all men" claims.

[Hawkmoth]

I've said it before but it is very interesting that an Axiom supplied now looks entirely different to what they looked like when first launched.

 

Rather clever of them to have come up with the perfect design, only to apparently completely scrap it, and come up with an entirely different perfect design.

Yes, that one looks totally different to one we had fitted in 2011. The boat did seem to stop better, but felt she was over propped as when we got on a river we could only make about 1900 PRM flat out with a Vetus 42.

Bob