While cleaning out our new boat I cam across (2) 4 blade props the previous owner didnt tell me were under the seats in the cabin (bonus) maybe he forgot them.

My question is, and dont jump on me too bad because IM NEW to powerboating. I have 3 blade props on our Bravo1's now. What will the 4 blade props do for us?

What do you have for a boat, what power, and most important, what exactly are the props, both the 3 blade and the 4 blade?

lutz the 4 blades will usually hook up better and carry the bow higher out of the water. less wetted surface usually means faster except you now have one extra blade dragging through the water which means slower. so you will have to experiment as to which is better. the formula is a heavy boat so the 4 may help get the boat out of the water. you may gain in mid range and lose on top end. what 4 blades are they.

later

Four blade props differ in characteristics. Hydromotive Quad IV's for instance are designed to lift the stern, not the bow. On my 311-SR1, which is an ass-heavy boat, the Quad IV's were a definite advantage over the Mirage 3 blades the boat came with. By lifting the stern up, I reduced drag, kind of like having a shorter "X" demension. I gained 6/7 mph at cruise speed (3300 rpms) and 3 mph on the top end. This was measured by GPS.

Other boats, depending on their natural ride attitude might suffer from a stern lifting prop.

Like "Later" said, 4 blades will put you on plane quicker and easier, generally give you a stronger midrange, and top end will depend on the boat and what prop you run.

In general circumstances, whatever that might be, when you go from a 3 blade to a 4 blade, you should go down an inch or two in pitch, to counteract the additional drag as "Later" pointed out. Again, in my own case I actually went up one inch in pitch. Ultimately it's a case by case situation.

Put em on and see what happens.....

formula and Later, Thanks. I have a 311sr1 with 454's and bravo 1's. Im not sure of the pitch of the 3 or 4 blade props but will ck when at loto this weekend. Im assuming the 3 blade are standard from Merc with the Bravo 1 drives.

If your 454's are Mags (365 h.p.) and 1.5 ratio drives , you should be turning 23 pitch Mirage (3 blade)props on this boat. The pitch is usually stamped into the barrel of the prop. This is a decent prop for stock power, but as Formula Outlaw said, there are potentially some performance advantages with 4 blade props. A 22 pitch 4 blade should work well with your set-up, but you need to put them on and try them. Make sure you put the props on in correct rotation (turning outward). If you switch them, the boat will go backward when shifted into forward, and move forward when shifted into reverse.

Lutz, try to get your hands on a pair of Quad IVs. Think you will be impressed. The guys at Hydromotive spent about thirty minutes on the phone with me and told me exactly what I could expect and why. They nailed it right on the money. Your boat will love the Quad IV's as mine did. The Hydromotives are a totally different prop than the Bravo 1 four blades. The Bravos, I believe, I more of a "bow lifting" prop. Eithe way, try what you have and see what happens. If you get a chance, try a set of Quad IV's. You won't be sorry. Russ

Just thought of this. I run in salt water which usually allows a boat to perform slightly better. As you are in fresh, you may not see quite the same results. I'm only guessing here, but the thought crossed my mind.

Often the mid-range speed increases several MPH at the same rpm, but at a loss of a few mph at the top. Also, hydromotive's pitches are about 3 more than bravo in real-world use. ie a 24 hydro motive is similar to a 27 Bravo (if such a thing existed) or a 27 mirage. I'm repeating what my engine builder told me, not my personal experience.

Lutz they are probably junk so you should just sent them to me....

Give them a try. Chances are there is a reason that they were in the bilge or were ever you found them LOL. However ya never know they may suite your driving style. You may also find that they had them on the boat before they did the motor mods. If this is the case then they will be pitched to shallow. If there is a HUGE pitch difference from one to the other then I would guess that the 4 blades were from before motor mods.

Jon