[Public-List] Propellors

[Rod Symmes]

Heh folks - those props were made LONG before computers controlled machining.  Perfection was not an option (or necessary ).  There was much hand work and craftsmanship  involved.
It is not important that the hole appears centered in the hub but rather that it be central and perpendicular to the blades and is it balanced dynamically.
My two cents worth.

Cheers,  Rod

-------- Original message --------
From: Gordon Laco via Public-List
Date:24-06-2019 8:27 AM (GMT-05:00)
To: Alberg 30 Public List -- open to all
Cc: Gordon Laco
Subject: [Public-List] Propellors

So there I was, yakking it up with a friend about how pleased I am with my new prop… besides the performance I commented how much quieter the boat is under power with the narrow three blader we have now than she was with the stock two blade one she came out of Whitby Boatworks with… and which she had fitted to her for all of the previous 49 years of service.

My friend asked me what pitch and diameter the old prop was.  I’d forgotten so I took it off my book shelf where it is now an ornament.   What did I discover?  The damned shaft hole is off-centre.   Yes, the prop was made with the shaft hole off-centre.   Crazy.  Well no wonder the new prop is ‘quieter’.    Three blades are of course smoother than two due to at least two blades always in clear flow whereas with a two blade prop the whole thing is blanketed by the sternpost twice per rotation… but off centre…. that must really have made whatever was inherent in the thing worse.

Onwards…

Gordon Laco
Surprise #426




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