Pitch is Pitch correct ?

[lohring]

I like to think about propellers like airfoils. Slip is another way of measuring angle of attack. The leading edge pitch shouldn't have too much slip or the prop will become inefficient. Conversely, the boat won't go much faster than zero slip on the leading edge pitch because the angle of attack starts getting negative. The trailing edge will have greater pitch to generate thrust. This can take the form of gradual progression or more sudden cup. The lower the thrust requirement, the lower the progression. Thus riggers usually run props with small amounts of progression and monos like lots of cup. The "average" pitch is what prop ratings show.

We've bent so much pitch into propellers that only the outer area was running a positive angle of attack. There was over 50% trailing edge slip. That happens when rpm is limited but you still want to go faster.

Lohring Miller

[carlcisneros]

Gary, look at your video once more.
do you see your rooster tail on the boat?
THAT is the TYPE of water you are looking for.
ONE SOLID WALL OF WATER. no pulsing done at all except when you ran over your own wakes.
THAT is what you are looking for. SOLID WATER

Also, you might try the ABC 1816/3 blade cleaver. (they can be a pain to get hooked up) once they ARE hooked up
(the 3 blade cleaver props) watch out!!!!!
The blade area on them is actually less that that of the 2 bladed cleavers that Jim makes.

there is one more little thing on the ABC props, they have what Jim Schaefer refers to as a hidden pitch on the trailing edge.
It is from anywhere from 4.32 to and up to 4.78" right on the trailing edge. ( and that is in addition to the props actual pitch)
I have done alot of testing on the smaller props for Jim a couple years ago for the 20 nitro riggers (actually the CMB Valvola 21) and man, can he make props.
I did testing on the 1500, 1600 and 1700 series for him.

[Gary]

Just ran some 96's so almost to my goal. Carlcisneros, that rooster tail dosent seem to be to much? I would think minimal rooster means more push and less spray.