Prop Slip Calculator

[Fr. Frank]

According to the website calculator mine was 8%. is that good or bad?

8% slip is astonishingly good. People pay THOUSANDS of dollars to get a single prop with less than 10% slip at WOT and less than 15% slip at cruise.

Now go run at your favorite cruising speed, and record speed & rpm, and see what your slip is then. A very good prop will have 15-20% slip at cruise. Less than 15% slip at cruise is very rarely heard of, although back when new SS props were $375-$500, I once spent over $700 on a completely custom prop from PowerTech, and got 12% slip at cruise, and 8.8% slip at WOT with Merc 2.0L XR4 V6 on the back of the boat below.