props 3 vs 4 and brass vs stainless

[yllw20]

Anyone out there switch from a 3blade to a 4 blade prop and/or switched to stainless from brass?
Is the difference noticable? and if so what is different?

[aneal000]

Props make all the difference in the world... basically the difference between 3 and 4 blade props are as follows, when comparing the two generally 3 blade props have a better top end and the 4 blade props have a better hole shot. This of course if similar pitch and diameters are being compared. Also a 4 blade prop will typically operate smoother than a 3 blade, or you will notice less vibration with a 4 blade.

As far as material the brass has alwasy been standard issue on inboards, some use Nibral, which is a Brass/Nickle alloy, or slightly harder than brass, but the main difference is what happens when you hit something. If you nail a log with a brass prop chances are you are going to ding it up. It is designed to give first, like as in before your propshaft. A stainless prop will offer the advantage of being stiffer, so if you are comparing same pitch props in brass and stainless you will typically have a little better hole shot and top end with the stainless. The stainless is stronger and will not flex. Having said that if you nail a small log with the stainless it usually won't even hurt it, due to how strong it is, now you nail something big and hard like a dike and you run the risk of shearing the propshaft keypin. But then again you nail something like a dike with a brass prop and chances are you will do the same damage! Once again with all of that said the new machined brass props are pretty sweet! No vibrations! Perfectly cut by a CNC machine every time. But you can't get them in Stainless, yet!

[Sammamish22V]

I have an Acme 4 blade that was repitched and recupped for more low end to compesate for the 2k or so in ballast that I have. It made a HUGE difference. Very little bow rise and the boat gets on plane in just a few seconds, even if we have a boat load of people and it is fully weighted. For $100, it was a much better upgrade then spending $3k to $5k for a bigger engine. I probably lost 5 to 7 MPH off the top end, but I never take the boat above 35 MPH anyways, so no biggie.

If you call ACME, they will tell you exactly what you need. I highly recommend them.

[edwin]

one additional benefit of the 4 blade prop is they often cavitate less than a 3 blade while turning sharply, especially to the left on a left handed prop. have a friend with a 21i that saw a major improvement in performance by swapping his 3 blade for a 4 blade.

[dajuice]

Does Acme know the specs for best results with different boats? Also how do you contact them. I hit a rock last season with my factory prop (4 blade) and one of them has a very small scrape/dent. Does getting them sharpened help? Interested in getting a new one if it helps the ride/handeling. Thanks