[Public-List] Propellors

[Gordon Laco]

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