TOPIC: aluminum versus bronze prop

hello,i was wondering if anyone might some input, i have a 1971 50hp merc with a 15 pitch 3 blade aluminum prop, if i were to try a bronze prop of the same pitch would i see any performance difference? also what would the advantages/diadvantages be between a 2 blade vs. a 3 blade be?
thanks

I'm not sure how Mercurys shift, but in OMC stuff, the brass props tend to wear out the shift mechanisms.

not so with the mercs. not much difference between aluminum and bronze in performance.

3 blades are a smoother ride, bronze may be faster....or not. I own over 125 props and some are the same, but that doesnt mean they are the same, I have 3 22p chopper spd-race props, same part # but,they all give me different spds. I say try any and all props you can find.

I agree - props are like potato chips - you can't have just one!

Ponyboy!!!!

My birthday, (no.74), is soon--send me a Laser II 20" or 21" for my Merc 1000 so I can go fast!!!! (Ha!ha!) Bill bought prop shown here as it did not work well on the Merc 1000.

The way I always heard it was aluminum tends to flatten out and loose some of its pitch at high speed, so you loose some of your top end. Also bronze and stainless are easier to do a quality repair job on.
They also look better!!!!!
Bill

The biggest thing is bronze can be made THINNER to support the same thrust load as aluminum. Thinner = less drag.

Typically the bronze prop was more of a performance prop over the aluminum one back in the day.

Now stainless took over.

But on boats traveling under 40 mph your not going to know the difference between aluminum bronze or stainless all things equal on our old motors. As long as they are in good shape.
Conrad

thanks for all the replies, i take the kids water skiing occasionally and i was thinking maybe a bronze might give me a little more power out of the hole.

Years ago I had a '70 50hp. It had an aluminum 13" pitch prop on it. I ran into a deal on a 11" pitch stainless and it gave me more out of the hole and I kept the same top end at the same RPM.
Bill

1 other advantage in old merc brass over aluminum is.....
tuning your props....you can ad more pitch to a brass prop than you can an aluminum,I agree everything as previously stated brass doesnt loose it pitch flattening out under load as aluminum and posted & with Conrad you wont feel much of a difference with the samller hp under 40-50mph

When I was testing props over the last year on my G3, I had problems with the old Merc/Kiekhaefer bronze 2 blades holding on during take-off and cornering. Couldnt trim a bunch with them before they lost bite...They didn't have any kind of cup though.

I had much better bite with the 3 blade and even better with the 3 blade cupped aluminum Quicksilver props. Of all of these (about 12 props) that I tested I liked the Quicksilver Black Diamond aluminum props the best (not expensive, uses the flo-torque hubs)

I have recently moved to stainless quicksilver props and I am now seeing better top end, but I don't have enough experience with these to say anything.

Dean

I am a believer in 2 blade bronze props under certain conditions. First, the bronze props are not raked and do not provide bow lift. Second, they need cupping to bite out of the hole and while turning sharply.

My Glastron V-153 with a 115 HP Mercury ran 53.5 MPH GPS with a 2 blade 21" pitch bronze Quicksilver prop, quicker than other stainless steel props by far. The blades are razor sharp. But get the right part number when getting the 21" pitch, as Mercury had older designs that were not efficient. Get 48-49630-21.