To polish or not to polish?
 

When BBlades sent me my Labbed 25p Mirage + last spring it was a dull finish. Last week I had a little work done to it and the shop asked me if I wanted it polished or not. I said no, but only because thats how it came back from bblades. My question is, is there any reason not to have a prop polished? The boat only runs in the mid-60s.

Could be wrong, but I think that the prop finish is strictly a cosmetic thing. If it was supposed to be polished, for some reason, then BBlades would have done it. I have to agree with your reasoning.

The "dull" finish is a part of lab finishing. I'll let Brett from BBlades explain exactly how it works, but it affects the way water flows over the surface of your prop. Water actaully flows better over a slightly rough surface as compared to a smooth (polished) one. If you simply polish a lab finished prop, you will loose RPM's.

Hi Polish is only a "bling" thing.

Some prop shops will argue till their blue in the face that Hi Polish is the way to go. But, usually it is because they have always polished the SS props they work on and take pride in the polish job they do. A number of years prior to my moving into the Mercury Racing propeller department, my boss and the head engineer for Merc hydrodynamics tested satin finish against hi polish and the major majority of the time (not all the time) the satin finish was 1 mph faster.
Think of a drop of water on a table. Touch the water with the smooth rounded bottom of a spoon and lift slowly. Notice the elasticity of the water adhering to the spoon. Now sandpaper the spoon bottom and try it again. The water will not adhere to the spoon. This is a slightly gross exaggeration of the affect but it does represent what is going on here. Very slight (very slight) grind marks do the same thing on propeller blades.

We are about speed and efficiency at BBLADES. Therefore our Labbed and race propellers come with our race satin finish. However, we will gladly hi polish your propeller to look like a chrome bumper if that is what you prefer. You just tell us what you want.

Brett

Thanks Brett. Thats what I figured, just more curious than anything else. Thanks for your advise. Love my prop from you guys by the way

im curious tho...i just bought a set of 28 merc choppers and they came polished from the factory???? if they are slower polished then why would merc do this???

I agree with Brett about the customer "bling" factor......
Most customers want a good looking prop when they get finished spending a few $$$'s.
Highly polished props do not corrode as badly as satin finished props.

We did some testing in the early years...... Built a standard, high polished prop, took it to the lake for testing..... came back & put a satin finish & then ran it again...... then put a polish back on it & tested a third time..... We couldn't tell any real difference in the performance..... so it ends up being there for the customer's satisfaction.

Most of the props we do, end up being highly polished unless the customer requests a satin finish.
I do build a few racing props that are satin finish & ALL my personal props are satin.

Thanks,
Tim Bostic
Hoss Marine Props

On average a satin finish is .0023 mph faster than polished. :D

to heck wit going faster :lolhit:...its all about the lookin good:cool-smiley-026:

Gimme dat bling baby , polished really looks faster ! http://i1243.photobucket.com/albums/...ckeredflag.gif

Where did you come up with that? I think you might be off a little/bunch.



2 tonchevy, As far as Merc putting Hi Polish on Chopper 2's.................there is a slightly long story I will shorten. You bought stock Chopper 2's. If you bought Labbed Chopper 2's, they would have been Satin finished. Scott (Merc Racing) decided to go Hi Polish on the stock OB cleavers and choppers because of the bling affect and production processes that I will not divulge.


Bostic, I said it is up to the customer how they want the finish. I didn't say there is no difference in performance. I believe/know there is a difference in performance. On average 1 mph or less can be seen but we have simply put our satin finish on out of the box props and have seen gains close to 2mph. Most of those results were on single engine OB boats but twin stern drives get results too.
Again, I've had this dicussion turned into a argument before. It's simply not worth the waste of time trying to talk somebody into it. That's why we let the customer decide. If they want our advice, it will always be satin race finish. Believe me, there is a trick to putting that finish on too. You need the correct equipment and a ton practice.


Brett

Mr. Anderson, Sorry to get your feather's ruffled.
I'm not trying to start an argument here..... just stating what our testing showed yrs. ago.
If someone (Mercury or you for that matter) tested it & said it was 1 mph faster, then that's good enough for me?
I'm not saying that the 1 or 2 mph gain is incorrect ..... all I stated was our results.... no change in RPM & no change in MPH..... Again, sorry if our results didn't match yours?
I'm sure we didn't know how to put a "special" satin finish on the prop in the first place, since everybody knows how to put a high polish on one. :cartman:

Again, Sorry for the Mis-Understanding,
Tim Bostic
Hoss Marine Props

Tim,

No harm done.

I am just stating our findings at BBLADES and Mercury Racing from much testing. You need to test these things more than once.

Thanks Brett

Yes, I agree about multiple testing.

Our actual test was done to determine whether polishing a prop increased performance & we determined it didn't help much at all, but decided that the "bling" factor was necessary for the customer, so we worked on making a beautiful prop along with the added performance of a custom prop.
(Like I said, my own props are satin finish - hehe!!!!)

Thanks,
Tim Bostic
Hoss Marine Props

ok thanks for clearing that up Brett!

so would a feasible course of action be: establish a baseline with my 28 "stock" chopper 2s and then try a lab finish if i need more rpm???

2tonchevy,
Testing the stock propeller first is the best way to determine what kind of lab finish would be needed.

Thanks Brett

Makes perfect sense. The adhesive forces of the water are greater than the waters cohesive forces. Water would rather stick to the spoon (prop) than stick to itself. Just like the concave meniscus in a glass or beaker of water. The water travels up the side of the glass. This would result as drag on the prop. The slight (patent pending) grinding/satin finish would break the slight adhesion of the water to the prop.

Cohesion: Water is attracted to water
Adhesion: Water is attracted to other substances