3 blade Vs. 4 blade - thoughts

[KBM]

Greetings all - was doing some reading on 4 blade props. I have a 2002 Seafarer with a 2002 Yam 225 4 stroke. I use it mainly for inshore and some near shore. I am interested to know if anyone has experience or opinion on what putting a 4 blade prop would do for me. Huge thanks in advance for any response.

 

[seasick]

You can't make an apples to apples comparison just by comparing 3 blade to 4 blade. I general a 4 blade will give better thrust(quicker on plane) at lower revs but will reduce the WOT top end speed. A 4 blade prop if optimized may also be a different diameter than a 3 blade for a given boat/motor

Depending on your wishes and needs, a good prop shop can recommend a prop best suited for your desired performance numbers.

 

[Ky Grady]

I had the same setup as you, just a few years newer. Switching to a PowerTech 4 blade prop was a huge gain. The F225 lacks the midrange grunt to push our boats up and out. Changing props helped it out greatly. Get with Ken at Prop God's and tell him what you have and what you're looking for. The F225, as is, will work with the 3 blade, but going to 4 blades was an improvement.

I upgraded motors to a F250, but still kept my PowerTech 4 blade to run on it. Just recently had the rods replaced in the hub, so looking forward to running it next month on our annual guy's trip to South Carolina.



Same prop, old motor.

 

[wspitler]

Don’t forget that when repowering, the engines may have different lower unit gear ratios so the engine RPM may not correspond to the same prop RPM on a different engine. For instance, the newer 4.2 L Yamaha four strokes have a different gear ratio than the older 3.3 L four strokes.

 

[Ky Grady]

Don’t forget that when repowering, the engines may have different lower unit gear ratios so the engine RPM may not correspond to the same prop RPM on a different engine. For instance, the newer 4.2 L Yamaha four strokes have a different gear ratio than the older 3.3 L four strokes.

I verified with Ken at Prop God's that I could use my current 4 blade on my new F250xcb before I installed it, otherwise I would have sold it.

 

[KBM]

You can't make an apples to apples comparison just by comparing 3 blade to 4 blade. I general a 4 blade will give better thrust(quicker on plane) at lower revs but will reduce the WOT top end speed. A 4 blade prop if optimized may also be a different diameter than a 3 blade for a given boat/motor

Depending on your wishes and needs, a good prop shop can recommend a prop best suited for your desired performance numbers.

Thank you so much! That is sound advice

 

[KBM]

I had the same setup as you, just a few years newer. Switching to a PowerTech 4 blade prop was a huge gain. The F225 lacks the midrange grunt to push our boats up and out. Changing props helped it out greatly. Get with Ken at Prop God's and tell him what you have and what you're looking for. The F225, as is, will work with the 3 blade, but going to 4 blades was an improvement.

I upgraded motors to a F250, but still kept my PowerTech 4 blade to run on it. Just recently had the rods replaced in the hub, so looking forward to running it next month on our annual guy's trip to South Carolina.

View attachment 35153

Same prop, old motor.

View attachment 35154

Beautiful set up. Thanks for the response. Very helpful to hear how folks with similar profile did with going from 3 to 4

 

[Hookup1]

I agree with Ky. Call Ken at PropGods.com. Have your performance numbers handy.

There is a huge misconception about going to a 4-blade and dropping pitch reducing your WOT speed. If you are not turnings the props properly you don't have that speed anyway!

Ken changed mine and it was a game changer. He said my props were overloaded even though I had the RPM's. The new props significantly improved the mid-range performance which is what I wanted with no loss of to- end speed. All I care about is mt 28 knot cruise and that was unchanged. Tanks Ken! I now have mid-range planing capability I never had.