Importance of Diameter in Prop Selection???
 

The ideal prop for my boat is a four blade 14.5 x 18. I've found a
used prop that's 13.5 x 19. Would this prop be similar in performance
to the 14.5 x 18? In other word, does decreasing an inch in diameter
have the same effect as increasing an inch in pitch?

~J.

In article .com,
says...

The ideal prop for my boat is a four blade 14.5 x 18. I've found a
used prop that's 13.5 x 19. Would this prop be similar in performance
to the 14.5 x 18? In other word, does decreasing an inch in diameter
have the same effect as increasing an inch in pitch?

~J.

A larger diameter is generally more efficient. The prop you found will
probably suffer at low speed, or under heavy load. To reduce the diameter
will increase your engine rpm's, but the larger pitch would bring them
right back down again, however, your smaller diameter just won't work
as effectively, and the result may not be worth the investment.

Here is everything you ever wanted to know about props.
http://boatfix.com/how/props.html


"John Davison" wrote in message
oups.com...
The ideal prop for my boat is a four blade 14.5 x 18. I've found a
used prop that's 13.5 x 19. Would this prop be similar in performance
to the 14.5 x 18? In other word, does decreasing an inch in diameter
have the same effect as increasing an inch in pitch?

~J.

In general you should use the largest diameter prop that your boat is
capable of swinging, and that is determined by tip clearance. If tip
clearance from blade to hull is too small, the shaft loading becomes
asymetric and will result in excessive wear and vibration. The normal
clearance recommendation is for no less than 20 to 30% of prop
diameter. On the other hand, using a prop with too small a diameter
will result in greater slip under heavy load. If the used prop is a
bargain you could always keep it as a spare if it doesn't perform to
your liking.

I know props have been known to kill boaters. I heard the democrats are
trying to make them illegal.


"IBNFSHN" wrote in message
news:3qVCe.75657$%Z2.75215@lakeread08...
Here is everything you ever wanted to know about props.
http://boatfix.com/how/props.html


"John Davison" wrote in message
oups.com...
The ideal prop for my boat is a four blade 14.5 x 18. I've found a
used prop that's 13.5 x 19. Would this prop be similar in performance
to the 14.5 x 18? In other word, does decreasing an inch in diameter
have the same effect as increasing an inch in pitch?

~J.

"Real Name" wrote in message
...
I know props have been known to kill boaters. I heard the democrats are
trying to make them illegal.

That would be fundiedems :-)



"IBNFSHN" wrote in message
news:3qVCe.75657$%Z2.75215@lakeread08...
Here is everything you ever wanted to know about props.
http://boatfix.com/how/props.html


"John Davison" wrote in message
oups.com...
The ideal prop for my boat is a four blade 14.5 x 18. I've found a
used prop that's 13.5 x 19. Would this prop be similar in performance
to the 14.5 x 18? In other word, does decreasing an inch in diameter
have the same effect as increasing an inch in pitch?

~J.