Tuesday, 19 October 2010

The Axiom Propeller

Monday 11th October - Early start this morning - up at 05:00 hours and George is so excited - we're having an Axiom Propeller fitted today by Mark in the Marina Workshop.
Sunrise from our berth at 06:40
moving slowly around the marina ..
.. in the mist .. 
just after 08:00
Moored up at the workshop - the duck on the tiller watching the sun rise.
Over to George now and that Axiom Propeller -
We had been having problems with our propeller.  When we were cruising at anything from 900 to 1400 revs we were getting lots of cavitation, at 1400 revs the noise was terrible and for the added revs, the boat didn't appear to be going any faster.  Also at 1400 revs the tiller was vibrating really badly and often we had to slow down to stop the vibration.  If we had to stop in an emergency, it would take the boat at least four times its length to stop, consequently, we normally failed to miss whatever it was we were trying to avoid!  If we were reversing, the stern would slew to port (it's called prop walk) consequently when we came in to moor onto a starboard mooring if I put the boat into reverse to stop, the stern would move away from the bank.  It was ok mooring to port as the reverse would pull us into the bank.  I had been reading about the development of the Axiom and the fact that Alan Watts (the designer) had been granted a patent only because the design was so radically different from the standard marine screw, which had not been changed since the late 1800s.
So we bought an Axiom Propeller! (not cheap!!)
This is Mark from Tattenhall Marina workshop taking the rudder off; we decided to do the change with the boat in the water as the marina charge £298 to take the boat out!
The prop and shaft out of the water
Difficult to believe that this plywood blank is all that is stopping the water rushing in.
This is me, totally focussed on the blank, to watch for leaks
New prop fitted, just needs a split pin through the nut
Ready to lower into the water and feed it into the shaft housing, Mark is making doubly sure that the knot is a good'n.
Bums on show for this difficult manoeuvre!
Getting the rudder ready for fitting
Almost there
Smiles of relief as the rudder is finally fixed in place it had taken about 3 1/2 hours start to finish.
We took it onto the cut for a test run and were amazed at the difference.  There was no cavitation at all; we could actually hear the engine purring away for the first time.  I took it up to 2000 rpm for a short burst,still no cavitation!  No tiller vibration.  The boat moves smoothly through the water with little or no bow wave or wash at the rear.  It also appears to move quicker for the same amount of revs (the literature says they estimate a 5-7% fuel saving and I believe this could be accurate).  There is no prop walk so when we moor, the boat pulls up straight; it also reverses in a straight line and stops easily within its own boat length even when travelling at speed, if you could call 4mph fast!  All in all we are chuffed with the performance so far; we have yet to try it in locks and Carol is looking forward to running the slalom going up Audlem Locks!!
Will keep you posted on any further occurrences as we find them on our journey.

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