Bravo III 4 blade vs 3 blade

[alldodge]

The current advertising from Merc is the 4 blade props provide better hole shot and mid range speed. Merc doesn't mention to much about top end, while other forums indicate that top end does suffer.

Most of my actual test I have done with any prop with more blades provides more lift but also increases drag, leaving out bass boat types.

I'm looking into the possibility of getting new props for my heavy single engine cruiser, and would like to know if anyone has tried or seen any data on the differences

 

[Tail_Gunner]

Looks like Blades has some input i am sure hes the guy to go to on this topic: http://midwestboatparty.com/forum/showthread.php?t=20568&s=dfd236fc9351da841482b113f465ad01

 

[alldodge]

Looks like Blades has some input i am sure hes the guy to go to on this topic: http://midwestboatparty.com/forum/showthread.php?t=20568&s=dfd236fc9351da841482b113f465ad01

Thanks TG, that was a very good read, and since the thread is from 2009 I wonder if BBlades has any new info. May need to sign up to another forum :spy: and get some inside skinny

 

[Texasmark]

I understand your request but a cruiser to me is a heavy boat requiring a lot of water contact to get the most out of your prop. I'm thinking 35-40 max WOT kind of thing, heavy boat. I'd put a 4 on her in a heart beat. When excluding ocean racers (different species), the more blades you add the more the blades get in each other's way at high rpms/speeds so the fewer the better. However, when you need thrust, the blade does the thrusting and the more the merrier.

Mark

 

[tpenfield]

Given your imminent increase in HP, you probably would want a 4/3 set in order to avoid potential cavitation of a 3/3 set that the thread link discusses.

What are you looking at for price $1K+ ???

 

[alldodge]

My original 415HP motor with a 2.00 ratio drive brought me to the 47mph at 5200rpm. If these are put into the prop slip calculator it comes to about 20 percent slip.

The new 545HP motor will have a 1.65 ratio drive (ordered yesterday) so I can use my original prop sets (20, 22, 22 cupped and 24). I'm thinking that if my top speed makes it to 55mph that will be plenty. Not really looking for top speed anyway, and hardly ever run the boat WOT.

If I need or want a new set I'm looking at the 4/3. Ebay has several used for under 1K, new just isn't worth the extra coin IMO for a prop. Don't see cavitation happening often unless I start getting into high speed hard turns