4 blade vs 3 blade

[TheRattler]

I am kinda new to this prop stuff. What are the pro/con with 4 blade props vs 3 blade props??

[REW]

I suppose that the biggest difference is that one prop has one more blade than the other.

Seriously, a 4 blade prop will give you added blade area.
As a result of the added prop area, the motor will see a larger load if you try to run the same size 4 blade as a 3 blade prop.

So, most folks who switch from a well running 3 blade prop will select a 4 blade prop that is both smaller in diameter and also has less pitch. By doing both of these things, the load on the motor stays about the same.

But, as you might imagine, if you go down in pitch, you will likely lose top end - assuming that you can spin both props at the same rpm.


But, with the lesser pitch and larger blade area, you generally have a better hole shot, and mainly a better mid range.

Many folks who work rough water - i..e. large waves like to use a 4 blade prop for these reasons.

However, many folks have found - including myself, that due to the extra blade, reverse performance can suffer greatly.
i.e. a motor that can back troll very well with a 3 blade prop may not back troll at all with a 4 blade prop. i.e. many four blade props on many motors simply do not pull the boat very well when run in reverse.

I prefer to have a good high pitch 3 blade for my boat, as well as a good lower pitch 3 blade for my boat as well as a mid pitch range 4 blade prop for my boat.

Then, depending on the conditions that I am going to use the boat, and how I am going to use the boat for the day - I can put the prop on the motor that lets the motor and boat do its best for the particular task at hand.

Good luck
REW

[cc-rider]

The basic difference is wrapped up in top speed vs. holeshot and "grip". A 4 blade prop will provide you with better holeshot and better grip. Better grip meaning less blow-out when trying to turn and less blow out in rough water. A 3 blade prop will provide you with better top speed.

When it comes to efficiency and gas mileage....that usually is determined on how efficient the boat, motor, and prop all work together to acheive the best mileage. Some boats will respond better to either the 3 or the 4 blade. The only way to get a definitive answer on this is to test, test, test with your specific boat and motor.

You should give us some information on your boat and motor and props you are thinking of and we can give a bit better advice.

[TheRattler]

Tracker Targa 1900 Fiberglass. Mercury 175 EFI

currently it has a 4 blade

[TroyMansfield]

in the past we ran 3 blades but now on our guide boats we run 21pitch high fives on 200hp mercs and 225 opti, I can put 6 to 8 people in a boat and hardly notice the difference in weight other then a few mph on top end, hole shot is sweet, we also have a boat that with twin engines (225 optis) and run five blades 21s on that for light hauling (up to 6000lbs)and it will go 63mph empty, over that we drop to 17 pitch off shore 4 blades for pushing big loads(over 6000 to 10,000lbs) hole shot will rip your arms off, but fuel mileage and top speed is really comprimised, but she will push the load 45mph. A good prop selection all has to do with what you want to accomplish and how big a load your pushing, I know I could gain top end with a different prop set up, but these props have major grip, pretty hard to cavitate and I can rally hard in rapids and rough water, but like cc rider says it takes lots of testing and time to dial it in, but worth it to have a boat dialed in..... good luck on your search

[Edgewalter]

Tried a 4 blade same pitch same diameter as my 3 blade and the hole shot sucked and top end I lost at least 4 mph. Even power loading on the trailer sucked. 2011 merc 225 pro xs

[ChuckD]

I had to go to a 4 blade on my 175 EFI to keep it from blowing out in turns and rough waters. Slightly more speed, better hole shot, but worse fuel economy.