What are Lab props?
 

What's up Fella's and Gals? What are Lab props and what's the difference?

Do you mean labbed props? Labbed props are props that are fine tuned by someone like BBlades. You give them your horse power, speeds at certain RPMs, gear ratio and other things and they may add more or less cup and other magical things to the prop. This can give you more or less bow lift if needed. Night top speed among other things

Now if you really meant lab props than i don't know. I'm sure someone with more knowledge than the little bit I have will educate us shortly

You answered my question. Thank you. I guess it's "Labbed"

Bit stoopid here but don't they also thin down the blades slightly in some applications?
Thinner blade, finer cut through the water, lighter to spin but also not so strong if you like hitting things underwater. :)

RR

Yes they thin the blades and true the props as well.

Here's a nice description from Mercury Racing on what they do to their Bravo 1 Labbed Finished props:

Mercury Racing blueprints and hand finishes the tried and true Bravo 1 propeller to give them their lab finished designation. These are balanced, thinned, and sharpened when compared to a stock Bravo 1 and feature a satin finish instead of the factory polish. They are generally faster and more efficient at top speed, but slip more in the midrange due to their thinner blade profile. The main advantage of a Mercury Lab Finished propeller over private modification prop shop finishes are the Mercury Lab propellers are extremely consistent and always provide the same performance results. This especially eases twin engine application propeller selection as Mercury Lab propellers are always matched pairs. hub kit NOT included.

Using that as a segway to go off topic, is the satin finish a similar principle to that used on Speedmaster drives, Merc Racing outboards and similar which are painted with an 'orange peel' silver?

I'm assuming the textured finish helps to break up the water rather than stick to the high gloss Phantom Black.

Many years ago, a friend of mine sanded the Phantom Black off his Bravo and left it raw finish. Looked like some fancy ass racing unit but was still just a Bravo. He swore it was good for a couple of mph but I'm not so sure....

RR

You need to be specific on what you want out of your prop, it will NOT increase performance across all ranges, at least that's my experience. If you spend little time WOT but mostly at a quick cruise you'll be disappointed if you don't have your prop tuned for that application, vice versa. You can also experience less bite when getting on plane if they grind some of the cup out.

Investigate first, it's expensive and might not be what you wanted. I wound up with a balanced and sharpened stock Bravo worked best for MY style of boating.

ask 100 people you will get 100 different answers!

Its like a tire on a race car. The blades grab the water like rubber grabs the pavement. Each kind of tire serves a purpose but none do everything perfectly.
Each kind of prop will do something differently and make the boat better or worse in a certain enviroment.