3 blade to 4 blade prop pitch

For a 4-blade prop the N-1 term becomes 3 and the square root of 3 is 1732. They are both the exact same.

For example if you have a 15x8 2-blade prop the load factor that the prop places on the motor would be 15 x 15 x 15 x 8 or 27000.

3 blade to 4 blade prop pitch. 3 blade to 4 blade pitch conversion A 4 bld. Prop will get you on plane easier and stay on plane with less power. It may lower your top end a little.

Usually they drop 1 in pitch assuming your present prop is right on. As far as what pitch for your setup it depends on your max rated rpm and your present max rpm. The general rule of thumb for going from a 3 to a 4 bladed prop - if you are running at desired rpm right now is to go down one to possibly 2 inches of pitch.

If you are running too fast right now this is a good way to pull down the rpm. If you need more hole shot and are already running too slow you might have to go down 3 or 4 inches of prop. Since the horsepower is limited the RPMs drop and the speed will tend to drop with it.

This is why when going from a 3 blade prop to a 4 blade prop you usually drop an inch or more of the pitch to keep rpm parity. An example would be going from a 21 pitch 3 blade propeller to a. Since the horsepower is limited the RPMs drop and the speed will tend to drop with it.

Therefore when going from a 3-blade to a 4-blade the pitch is dropped an inch or two in order to keep rpm parity. It is this difference in pitch that causes any potential speed differential between the. 4 blade props tend to load the engine more - if you compare a 3 blade prop of identical blade size and pitch.

4 blade props tend to have a lower top speed. When asking about rpm - it is essential that you note my comment on the comparison between identical blade sizes with repect to both shape length size and design - when comparing 3 and 4 bladed props. Thanks in advance.

I went from a 3 blade 21p stainless to a 19p 4 blade stainless for the same revs on my DF140. 4 blade will use slightly more fuel but will grip better in the rough. I get zero cavitation with the 4 blade where the 3 blade used to blow out.

Never argue with an idiot. When moving from a 3 blade 16 X 215P to a 4 blade prop WE SHOULD HAVE selected the 4 blade 1525 X 22P in the first place as the 75 reduction in diameter had a dramatic effect on WOT RPM. At 500 and up there isnt much room for economical.

Typically when you add blades you get rid of some of the pitch. An example would be going from a 21 pitch 3 blade prop to a 19 pitch 4 blade prop. Yes the 4 and 5 blade props will get you a lower planing speed and is great for water sports like pulling a skier or wake boarder up out of the water.

The conversion for a 3 and 4 bladed propeller is a simple tasked if you know what 2 bladed propeller you use on a given Engine or Motor. For example on a three bladed propeller you would drop the diameter and keep the pitchOn a four bladed you would drop the diameter and the pitch. For instance if you had a two bladed 24-10 propeller and you wanted a three bladed you would use a 22-10.

3-Blade or 4-Blade Props. Three-blade props offer a nice compromise when it comes acceleration efficiency lift and speed. A four-blade propeller on the other hand can boost acceleration efficiency or lift but at the cost of a lower top speed.

Jim Hendricks Sport Fishing. To change from a 3-blade propeller to a 4 blade propeller what diameter or pitch modifications must be made to result in the same engine performance. The best solution is to have a free propeller analysis performed with the 3 and 4 blade propeller sizes accurately calculatedÔÇ For many vessels the same diameter propeller is used but the 4 blade propeller pitch is reduced by 1.

I received this response. We tested that boat with a couple of props. The Mirage Plus is a 3 blade the OFS4 and Rev 4 are both 4 blades.

The OFS4 cost 450 shipped. The Rev 4 cost 494 and you need a hub kit for 35. The Rev 4 was a little faster on top end but both gave good lift and held the boat well.

For a 3-blade prop the N-1 term is the square root of 2 which is 1414. For a 4-blade prop the N-1 term becomes 3 and the square root of 3 is 1732. For example if you have a 15x8 2-blade prop the load factor that the prop places on the motor would be 15 x 15 x 15 x 8 or 27000.

If you wanted a 4 blade on my old boat I run a mercury revolution 4. I also tried a mirage 23 pitch last year and they both ran about the same rpms top end. Maybe 1-2 mph diffenence top end but overall the 4 blade is smoother and I can stay on plane at lower speeds if its rough.

Rule of thumb decrease pitch 1 - 2 for an increase in Dia by 1 or going from 3 to 4 blades. Normally going to 4 blades is an advantage when Extra pulling power is required - towing heavy loads. Jango Feb 16 2007.

The difference between a 3-blade prop vs a 4-blade prop is that the 3-blade smaller blade ratio is faster with a higher top speed and the 4-blade higher blade ratio has a better hole-shot acceleration and better stern lift as well as better handling and fuel economy because it will keep you on plane at. But some of the accounts Ive read reported people increasing the pitch by one increment when they went 3-blade to a 4-blade and then they not only got better holeshot they also gained MPH. I am most concerned about gaining MPH.

My boat right now runs about 36mph 6100rpm trimmed out with just me and the stock 3-blade on the 50hp merc. A four blade gives better holeshot much better in cornering and the top end loss is negligible. At least on my 115 4 stroke.

Also I can run my motor higher in the water column with a 4 or 5 blade prop which actually gives me more top end as I dont get slippage and cavitation like I. But keep in mind pitch how far the boat is soppose to move with one turn of the prop. So by going to a smaller pitch you may slow down a little.

About 2 or 3 mph. 5 for a 5 blade. Oh and I have a friend that runs a 25p.

4 blade but he has a 250. And he has all the holes open. 3 Vs 4-Blade Props Same Diameter and pitch Discussion in General Conversation started by CaptDavet Jul 5 2010.

Page 1 of 3 1 2 3 Next Jul 5 2010 1. I have two propellers for my 270 Mackinaw mated to a Yanmar 315hp diesel. They are both the exact same.

As our graphic shows a propeller is identified as for instance 13 34 x 21 if it has a blade diameter 13 34 inches with a pitch of 21 inches the amount of forward travel in one revolution. The table below generally defines the terms.