Axiom prop - any experience here?

Rivers & creeks

Rivers & creeks

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I'm re-propping after the new engine and I've read the review of the Axiom, lots of claims which if correct would be jolly nice, I really like the lack of kick in astern, the equal stopping power and zero cavitation which will reduce noise and vibration. But it's a big investment so I'd value users input. Folders and the like wont fit the aperture BTW.

Thanks for input.
 
Spend the extra and get a Featherstream (which will almost certainly fit). The Axiom has been on the market for many years and has not made any impression in the yacht market. The only "test" found little difference from a fixed 3 blade for nearly twice the money, although it was on a low powered boat.
 
Thanks, I hadn't realised it has been on the market for so long.

Sadly a featherstream isn't made big enough, I need a 24 inch diameter and that's after getting rid of the current 31 inches prop!
 
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Colvic Watson said:
I really like the lack of kick in astern
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I'm always puzzled by this oft-quoted so-called advantage. Our boat has a marked kick to port when going astern and I value it as one of the most useful attributes when manoeuvring. Consider it as a unidirectional stern thruster!
 
I'll check, it's a 31" with moderate pitch and the boat is massively over propped. Is the basic theory that pitch gives speed and diameter gives low speed thrust?
 
Colvic Watson said:
I'll check, it's a 31" with moderate pitch and the boat is massively over propped. Is the basic theory that pitch gives speed and diameter gives low speed thrust?
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No. The boat is moved by the amount of water the prop will move which is a combination of its pitch and the speed at which it turns (minus inefficiencies!). Large slow turning props move more water than small faster turning props.

Put your boat's data with its new engine and box through the Propcalc programme on www.castlemarinme.co.uk to get a suggested ideal size.
 
Colvic Watson said:
I get a 404 on that address, I think I found the right one though and tried their prop call form and got a 404 :(
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Hi Simon

If no joy with others try the prop calculator I use http://www.vicprop.com/displacement_size.php

What I can not understand is from my records your boat originally has a Thorneycroft 230 75hp engine and PRM gearbox and I cannot believe they fitted a 31" prop to go with it
so someone may have changed it! I also assume the gearbox is original? and also your present 788mm dia prop is RH ?

Your proposed 600mm dia seems way too small, looking through my records of all the CW 34'-6" that I have done my ' Pre Buying Inspection Visits on' almost all have had near 750mm dia props (+/- 25mm), even the big fellas like the Jura class with 124hp Perkins had only 740 mm dia props.

Have you ever tried another prop size? but in between say about 700- 725mm dia and as said before I would not even think about fitting an Axion or other folding prop to a CW, I know at least two Fisher owners that had a bucket full of problems and went back to the conventional 3 blade fixed pitch RH props.

Anyhow if your going to re engine why worry the new engine supplier should tell you the size required to best suit the engine/gearbox.

As a side most owners who have had reconditioning jobs done of their Thorneycroft engines have said its the best thing they have done, however one caution to watch
is the Colvic Watson Veracity class like the Jura class all had ballast trim adjustments 'after fit out', most of the modern new engines are much lighter now and may also have
to be mounted in a slightly different engine bay position so you might inherent a new problems with ballast/trim with a lighter engine.

Mike
 
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You in case others get confused, the Axiom is not a folding prop, but has fixed blades to a unique design, developed for canal boats.
 
Yup and my new engine was fitted some time ago and the same weight as the old one ;)

The prop calc program recommends 21" by 15 pitch but props are more efficient with a larger diameter and a smaller pitch so 23" and 14 pitch would be better. Can you imagine the drag - even free spinning - of the present 31.5" monster! Which BTW is original.

Slightly over propping is a good thing on a sailboat but the present beast is silly and long term big over propping is well bad for an engine. Still Axiom will swap for a new size for free if they're wrong :) I'm nervous about the new technology even if the Tull soundtrack on their video is like totally their best song evvvvver.
 
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