4 blade vs 3 blade

[limitout]

(this post is just about prop research for a future purchase)

I was wondering what the true real expectations are when going from a 3 blade to a 4 blade prop?

im asking because I keep reading posts about steering torque being a concern when someone buys a 4 bladed prop so lets say you have a basic Teleflex steering cable setup and it does not have hydrolic or dual cable systems to reduce steering torque issues, what is there to expect when adding an extra blade?

I realize this can be a tough question so lets give it a few criteria:

50hp outboard on a 17 ft boat with side console steering and 1,000 lb. total weight load


so without discussing what can be done to "solve" any steering torque issues, I just wanted to know what are the expected steering torque issues and resulting changes in boat behavior if any

 

[smokeonthewater]

Re: 4 blade vs 3 blade

usually the 4 blade is easier to steer and will usually give better or much better hole shot and depending on the boat may have a slightly lower top speed.

 

[steelespike]

Re: 4 blade vs 3 blade

While torque steer can be the result of any prop change;I don't recall anyone having torque steer problems with a 4 blade.
Based on my experience I don't think a 4 blade is any more likely to have torque steer problems than any other prop.

 

[kfa4303]

Re: 4 blade vs 3 blade

Kind of depends on the boating you do most often. If you're looking for top end speed, 3-blade props are usually best, but if you need more low end torque for pulling tubes, skiers, or carrying heavy loads 4-blad props are generally best. Of course, hull design and final rpms will play a huge part in performance as well. Also, most modern motors have small adjustable fins on them to compensate for any torque steer you may have.

 

[limitout]

Re: 4 blade vs 3 blade

ok so its the 3 blade that has more of a tendency to cause torque steer (if you do have any) then a 4 blade? I thought it was the other way around

hmm, so going to 4 blade isn't a choice to make just for generic general applications but more a choice to make when you need more low end torque.

 

[dingbat]

Re: 4 blade vs 3 blade

hmm, so going to 4 blade isn't a choice to make just for generic general applications but more a choice to make when you need more low end torque.

The 4 blade does everything better than a 3 blade except provide top end speed.

I went from 17 x 14, 3-blade aluminum to a 17.25 x 14 4-blade stainless prop on a #5.5K boat.

Torque steer pretty much gone. I can walk away from the helm at any speed and expect the boat to stay on course. Your mileage may vary.

The 4 blade is much harder to break loose and blow out.

The biggest bad rap a 4 blade SS gets is the cost. Mine was over $600 when all was said and done

 

[smokeonthewater]

Re: 4 blade vs 3 blade

and on SOME applications the 4 blade CAN be faster on top speed too... IE a slow boat with a small motor might have excessive prop slip and a lower pitch 4 blade prop might actually make for a faster slow boat

 

[fishrdan]

Re: 4 blade vs 3 blade

^^^ yup, a 4 blade prop will reduce prop torque steer.

and on SOME applications the 4 blade CAN be faster on top speed too... IE a slow boat with a small motor might have excessive prop slip and a lower pitch 4 blade prop might actually make for a faster slow boat

Correct, I had a bad prop/boat combo before changing to a 4 blade prop. The old 3 blade 15.25x19P would only allow the engine to spin 4200RPM at 32MPH, while the new 14.5x18P 4 blade prop allows the engine to spin 4600RPM at 35-36MPH.

 

[limitout]

Re: 4 blade vs 3 blade

great info guys, thanks