Friday I was able to spend testing new-to-me labbed 30 Bravos. I am currently running non labbed 30 Bravos.

With the labbed props turning in, the best I could get was 78.6 MPH. I gained 400 rpm to 5100. With them turned out, the best was about 77 mph. at 5100 rpms. I had a great looking rooster tail!

Temp was about 72. Little wind. Little lake ripple, almost glass smooth. We ran both ways each configuration.

With the stock props, we turned 77.2 mph at 4700 rpm. I am disappointed in the speed change but like the rpm change.

My question is, how can the rpm change significantly but the speed not?

I'd suggest trying a set of stock 28's. The labbed 30's you tried were labbed to increase rpm and not necessarily speed. If you lab a prop by thinning and removing cup, you increase rpm, but typically lose or maintain speed.

If you move to the 28's and turn them to the limiters, your speed should be slightly faster with a better hole shot and top end with midrange suffering a little, but better overall response.

Who labbed them? It could be as simple as having some cup put back into the blades. At least in theory. More importantly, did your cruise speeds suffer with the labbed props? Ive tried several sets of labbed props. All were about 5 mph slower at 3500 rpms where I do most of my running.

I went back to a new pair of stock 28's. They have held up better after two seasons than my labbed ones after a couple months of use.