T&T: Propeller balancing

[Kurt Reno]

Just some thoughts for the group in general.



I have just balanced my propeller.  I can do that easily as my propeller is
a controllable pitch propeller that can be disassembled. To balance the
propeller,  I weighed each blade and found the blades to be 25 grams
difference.  To give some perspective,  this is a two blade 19" propeller.
I decided to shave some off of the heavy blade so I began measuring with
digital calipers.  I will be darned if I could measure any meaningful
difference so I decided to just sand the blade all over to match the other
blade in weight.



The difference in this small slow turning propeller is astounding. I have a
huge reduction in vibration and I am able to get the same speed out of the
boat with 150 rpm less on the engine.   1450rpm instead of 1600 to reach
hull speed.  Propeller speed is half of these figures.



The point is that I would not have expected this much benefit from balancing
a small slow turning propeller with only 25 grms difference.  Second, I
would not have guessed that these propeller blades would have come from the
factory with that much weight difference.  I would imagine that larger
propellers that turn faster would have a much bigger benefit. With today's
fuel prices, balancing the propellers may be something trawlerites might
consider.