Prop Math - Do I have this right?

[Motv18]

Beak, positive would be theory of 81mph and runs 81+ Often blamed on the prop being over pitched then rated.

[TraceF3]

OK so I bought a new Trophy Plus 25p for my Vegas. Ran it 55 river miles Saturday. At 4700 rpm I was making a true GPS 60 mph. That's only 5.7% slip. I'd say that's about perfect jack plate height and trim angle.

Comments?

[Euroski]

Also need to wonder how accurate the tach is?

[TraceF3]

How accurate is Smartcraft technology?

[David]

It's been over 30 years and I can't do the math anymore, but some slip is theoretically necessary to get forward propulsion. But...
Props are typically progressively pitched, so the advertised pitch is at some mid point on the blade
Buyers like low slip numbers, so the prop makers have an incentive to low ball their stated pitch

[Motv18]

Other then checking full throttle. Since stuff can change it looks good