Axiom Prop experience

[WotEver]

Hi all, below is a copy/paste of an email written by Mr Smelly's brother-in-law wherein he describes his experience of an Axiom. It's pasted exactly as written. 

There’s been a lot written/said about Axiom propellers, much of it from people who have never owned or used one so now that I’ve gone from standard turbine to Axiom and finally (?) to a Crowther, I’ve put these notes together for my ugly brother in law to post. Use them as a decision making aide or just to pull to pieces, I care not. All I will say is that if you haven’t used/experienced the Axiom propeller, your views are at best hearsay and at worst complete and utter bullocks (or something very similar). ;-)

I have a 66’ boat with an old 3 cylinder air-cooled Lister driving it and I don’t like over-revving the engine but do like to move at a reasonable speed rather than dawdle. That said, I consider a reasonable cruising speed to be around 3 mph with the top end of 4mph reserved for when speed is of the essence.

The boat draws around 31 inches at the double depth skeg when stationary (about 27” on the chine at the start of the rear swim) and when I bought it it wore a standard turbine style 22 x 14 prop. This original prop drove the boat reasonably well but it wouldn’t stop it at all and ‘walked’ the back end severely under hard reversing so I decided to change the propeller.

I did the research and read various reviews looking for a prop to improve stopping/reversing and picked Axiom. I contacted them and they recommended an 18” diameter prop with 28o of pitch – Axiom don’t do their pitches in terms of inches. This was the earlier type of Axiom prop with shorter squarer blades, I think they’ve since changed the design to longer blades (?). It did what it said on the tin in terms of improving stopping (vastly), reversing and the boat steered better at slow speeds. And whilst I was concerned at the reduction in diameter, I was happy with the purchase despite the cost. Bear in mind I could only compare the performance of the Axiom against the prop I’d taken off.

Up until last year it had always been a holiday boat, we didn’t travel far, fast or much on rivers and speed/power/thrust was never seen as an issue. Last year we moved aboard permanently and in taking on a short section of river under ‘yellows’ during our travels we seemed to lack the punch required and barely made it across even using far more revs than normal, it also seemed to struggle to reach a decent cruising speed judging by the multitude of boats that catch us up especially on longer pounds. As we intend to eventually travel far and wide, we decided to change the prop again for something specifically designed for us so we spoke to Crowthers. They were very good in terms of explanations especially when I expressed my concerns regarding backward steps once they confirmed intended diameter and pitch.

The Crowther manufactured ‘Lister’ style 22 x 15 prop was ordered and has now been fitted and in all honesty hasn’t improved things much although it does at least as well in all areas. The main improvement is in winding where it seems to turn the boat more easily. In general terms, it does seem to move more water or maybe it moves the water nearer the surface making it more visible?

Anyway, given all the above and solely on my boat, it would seem the Axiom definitely outdid a standard turbine prop and isn’t quite as good as a properly matched/styled propeller but given the reduced diameter, it will fit under a shallower rear end. Hand on heart, I wouldn’t recommend it for a slow revving engine as I still think it’s not fully right for a ‘thumper’ but that’s just my opinion based on my experiences, the final choice would lie with the purchaser.

Lastly, I really do need to re-trim my boat fore and aft which may alter current performance entirely and may have been the reason the Axiom has ‘underperformed’ since we move aboard with the increased weight etc. – who knows? But if it does make a vast difference I’ll let my ugly brother in law know.

[nicknorman]

I wonder what the price comparison is between his Axiom and his Crowther?

[alan_fincher]

The above really needs to explain what "old 3 cylinder air-cooled Lister" is fitted, as there is no comparison between say an SL3 and an HR3.  To know how quoted propeller sizes compare to ones that some of us have experience of, you would also need to know the reduction ratio of the box.

The Crowther recommended Lister prop sounds horribly undersized at 22 x 15 if the engine is anything like an HA3, HB3 or HR3, (even if on a 2:1 box, and certainly so if on 3:1), so assuming Crowthers have been given good information I can only assume the Lister is a less powerful model, maybe an SR3.  If so, I'm not really sure I would expect such an engine to give a stunning performance with a a 66' boat that is 31" deep on the skeg, howeer well matched the prop is to engine and gearbox.

I'm usually quick to criticise cases where an engine is (in my view) too big, but I would say a boat like that described needs an "H" rather than an "S" series Lister, and if it did have, I'd expect the prop to be far chunkier than that Crowther one.  It would be fine on cnalas with no flow, but, as the email suggests, probably a bit on the margin where any great flow is involved.

[bizzard]

Could be an ST3 30 odd hp.

[mrsmelly]

33 minutes ago, nicknorman said:

I wonder what the price comparison is between his Axiom and his Crowther?

He wouldnt tell me because I was taking the pee out of him for buying it in the first place. Suffice to sayit was more than a crowther.

22 minutes ago, alan_fincher said:

The above really needs to explain what "old 3 cylinder air-cooled Lister" is fitted, as there is no comparison between say an SL3 and an HR3.  To know how quoted propeller sizes compare to ones that some of us have experience of, you would also need to know the reduction ratio of the box.

The Crowther recommended Lister prop sounds horribly undersized at 22 x 15 if the engine is anything like an HA3, HB3 or HR3, (even if on a 2:1 box, and certainly so if on 3:1), so assuming Crowthers have been given good information I can only assume the Lister is a less powerful model, maybe an SR3.  If so, I'm not really sure I would expect such an engine to give a stunning performance with a a 66' boat that is 31" deep on the skeg, howeer well matched the prop is to engine and gearbox.

I'm usually quick to criticise cases where an engine is (in my view) too big, but I would say a boat like that described needs an "H" rather than an "S" series Lister, and if it did have, I'd expect the prop to be far chunkier than that Crowther one.  It would be fine on cnalas with no flow, but, as the email suggests, probably a bit on the margin where any great flow is involved.

Its an HB3 if I remember correctly, I will ask him. It was certainly noisey and doesnt even provide hot water so a bit of a nonsense realy but he will learn eventualy.

[alan_fincher]

16 minutes ago, mrsmelly said:

He wouldnt tell me because I was taking the pee out of him for buying it in the first place. Suffice to sayit was more than a crowther.

Its an HB3 if I remember correctly, I will ask him. It was certainly noisey and doesnt even provide hot water so a bit of a nonsense realy but he will learn eventualy.

Ignore me, I think I'm having a bad day!   Actuallt 22" x 15" is probably not a million miles out for a 3-blade, (provided the box is 2:1).  It would only be very undersized on a 3:1 box, (which is what I'm more used to)  - something more like 27" x 23", possibly, (provided enough space under the counter to swing that big!).

IMO these engines are better with the bigger reduction, (provided you have space for the prop, once again).

[mrsmelly]

1 minute ago, alan_fincher said:

Ignore me, I think I'm having a bad day!   Actuallt 22" x 15" is probably not a million miles out for a 3-blade, (provided the box is 2:1).  It would only be very undersized on a 3:1 box, (which is what I'm more used to)  - something more like 27" x 23", possibly, (provided enough space under the counter to swing that big!).

IMO these engines are better with the bigger reduction, (provided you have space for the prop, once again).

I always ignore you  I think you are right that its a 2 to 1 box. Geoff likes to tinker on his boat and actualy keeps it in bloomin first class condition he polishes the flippin polish!! he lavishes it with love ( and money ) bless him and just thought it may help someone to see his first hand experience. He doesnt do tinternet or forums so sent me the message in case the post would be helpful 

[Dalslandia]

The Axiom with 28 deg blade angle, will at 70% radii have an pitch of 21" on the 18" diameter propeller.

[Rose Narrowboats]

By "Lister style" does he mean an equipoise type blade please?

That was what genuine Lister props were, and, they don't stop for toffee compared to a conventional (ie roughly symmetrical) blade in my experience.

[mrsmelly]

3 hours ago, Rose Narrowboats said:

By "Lister style" does he mean an equipoise type blade please?

That was what genuine Lister props were, and, they don't stop for toffee compared to a conventional (ie roughly symmetrical) blade in my experience.

Good question. I will ask him when I speak with him in the week. 

[alan_fincher]

13 hours ago, Rose Narrowboats said:

By "Lister style" does he mean an equipoise type blade please?

That was what genuine Lister props were, and, they don't stop for toffee compared to a conventional (ie roughly symmetrical) blade in my experience.

Flamingo has a non symmetrical prop, which is actually made by Brunton with an identifying number, but when Brinklow Boats spoke to Brunton to try to find its history, it proved to be older than their records.

It's performance has been massively improved by re-pitching from something like 15" to 21", and is now very good in ahead, but I still think "adequate but not stunning" in reverse, (though hugely better than it was!)

I think the non-symmetrical shape may have something to do with this, but unless ever compared to a more symmetric one, it is only a theory.

I also think the shape contributes to it fouling less than I might expect, (a real bonus on a boat with no weed hatch) - when it was being refurbished at least one person referred to the design as "weed throwing".

More detail here.

[Dalslandia]

looks like a good propeller with medium skew

[X Alan W]

24 minutes ago, alan_fincher said:

Flamingo has a non symmetrical prop, which is actually made by Brunton with an identifying number, but when Brinklow Boats spoke to Brunton to try to find its history, it proved to be older than their records.

It's performance has been massively improved by re-pitching from something like 15" to 21", and is now very good in ahead, but I still think "adequate but not stunning" in reverse, (though hugely better than it was!)

I think the non-symmetrical shape may have something to do with this, but unless ever compared to a more symmetric one, it is only a theory.

I also think the shape contributes to it fouling less than I might expect, (a real bonus on a boat with no weed hatch) - when it was being refurbished at least one person referred to the design as "weed throwing".

More detail here.

The blade I had on "Lily"was 28x21 with direct drive max 600RPM it was similar shape to the illustrated one, & one time on Charity dock an old working boatman remarked "I see youv'e a rubbish slipping blade then" it did collect "junk" but in the amount  to a standard shaped blade I have no idea if it was better/worse

[Rose Narrowboats]

Alan - that's the type and I've also heard that blade pattern referred to as "weedless".

The quickest way I have found to halve the stopping distance of a boat fitted with a blade of that pattern is to replace it with a conventional shape blade which I have now done on many boats of my own and for customers. The equipoise ones also have a lower Blade Area Ratio (also called aspect ratio these days) than a "standard" (50% BAR) prop. so how much is the shape and how much is the BAR I'm not sure.

My experience with an 80% BAR prop. also suggests these are less prone to fouling than a 50%, whilst stopping as well a prop of much greater diameter.

[alan_fincher]

4 hours ago, Rose Narrowboats said:

Alan - that's the type and I've also heard that blade pattern referred to as "weedless".

The quickest way I have found to halve the stopping distance of a boat fitted with a blade of that pattern is to replace it with a conventional shape blade which I have now done on many boats of my own and for customers. The equipoise ones also have a lower Blade Area Ratio (also called aspect ratio these days) than a "standard" (50% BAR) prop. so how much is the shape and how much is the BAR I'm not sure.

My experience with an 80% BAR prop. also suggests these are less prone to fouling than a 50%, whilst stopping as well a prop of much greater diameter.

Very interesting - thanks.

I don't think I would be misrepresenting the majority view of the team down the arm if I said they didn't think the asymmetrical shape was a major factor in taking a while to stop. Feeling was repitched prop OK, given it is a very heavy boat, (equivalent to carrying at least a third of a full load, quite possibly more than that).

Your experience seems to say otherwise, and by choice I think I would prefer a conventional shaped blade.  However at the time we couldn't turn up a suitable second-hand one, and even not at Crowther replacement a new one was going to cost a lot.  (26" x 21" was the figure agreed as most suitable when opinions were averaged out).

Of course cost to change also includes further dockings, so I don't think we will be rusing into further experimentaion.  Forward performance is now good, reverse at least adequate unless someone throws a real curved ball at you, and weed / rubbish throwing seems very good (so far!).

[mrsmelly]

Just come back across this lol. Said bro in law who always swore by his old knacker thump thump engine in his deep draughted "traditional" boat when he was a hobby boater came out with us last summer for a big trip to include amongst others the Thames. Suffice to say he recently sold the old knacker and now lives on a modern Cruiser stern with a fab modern beta at the back. It takes some longer than others but he got there in the end.