On Mon, 17 Aug 2015 13:04:24 -0400, Justan Olphat
wrote:

On 8/17/2015 1:23 PM, wrote:
On Mon, 17 Aug 2015 10:27:40 -0400, Justan Olphat
wrote:

1. The Big Foot is a workboat motor

It is certainly not for "performance" as much as giving a good push at
a relatively lower speed.
Yamaha must only make workboat motors tho. My F70 is swinging the
exact same prop as my big foot used and that is the only lower they
sell.
Alternately you could argue that at 60-70 HP, you should be in the
larger prop. The difference between my F70 and Don's 60 are minimal
and 3-4 HP at most. That is from a little better breathing on the
intake side. You will only see that at WOT. I have about 0.3 hours at
anything even close to that.


Your boat fits nicely in the workboat catagory. Proper prop size is
whatever allows your engine to attain WOT mfg. suggested RPM. Your prop
is probably larger in diameter and shallow pitch. Probably 12 pitch.

It goes a little deeper than just matching RPM to prop diameter and
pitch.
High performance boats want the exact opposite of "big foot". They
have as small a gearcase as possible to reduce drag but they are
easier to break and low speed performance suffers.

OK Work boat ;-)

BTW 14x11