Why 4 blade props?

[Steve Melton]

I'm in the market for an Allison XB 21 and was wondering why it seems that all the Allisons I find are running 4 blade props and was curious as to why ? I've owned several boats over the years and have been able to get better performance and speed from 3 blade props. Is the hull design better suited to a 4 bladed prop?

 

[ROBERT CROSS]

Because Todd at Hydromotive recommended it & the 30p Lightening ET scared the pi$$ out of both of us......

 

[Steve Melton]

lol

 

[skewby]

darris the man that designed and builds the boats recommends 4 blade props on the xb 21's. on the 02 and 03's i always like 3 blade props better

 

[champ198]

4 blades are better for surfacing. Keep in mind you may be running that lower unit high on that 21 at anywhere from 1/2" below pad to even with the pad when you want to haul booty. Most boats like a heavy Champion 206 run 4" below pad (buried). I run a 29 4 blade Hydromotive XOB big barrel prop with thin blades on my 2+2 and have 1.62 gears (also recommended by Darris).

 

[GotMyAlly]

I'd approach that question from two angles.

First, three blades are generally bow lifting props. That may get you a couple miles per hour on a heavy boat that requires all of the trim to get to full speed (and are still pushing water). Allisons have a lot of lift built into the hull, to the point that full trim is detrimental. You may only run 75% up on the trim to get the boat running clean and free. Additional bow lift is not really necessary, so the three blade may not net you much. If anything, only a mph or so, instead of bigger gains that you might see on a lead sled.

Second, if you can run 95 with a 4 blade and have great holeshot and turn on a dime without the prop losing bite, why would you sacrifice the handling to run 96? Not much on the water is going to pass you at 95, and anything that can pass you at that speed is going to get you at 96 too.

 

[aeneas]

They are easy to drive. Todd made me a Hydromotive QIV O/T for my SuperSport and it was like driving with training wheels and still fast.

 

[fnshrmaster]

Good to hear. I just bought one for my XTB, looking forward to running it.

 

[ROBERT CROSS]

You won't be disappointed....1st class all the way.

 

[jeremy hood]

What 4 blade would y'all recommend on a xtb with a coned stock 150 turning 5800? Also tried a 25 chopper. It had a 75 yard hole shot and 52 was all I could get out of it level with the pad. Had it re hubed and nothing much changed. A little better holeshot anf no top end. Dealer that I got it from paid to have it done but when nothing changed and i traded it on another prop he got a little pissed about the re hub job and acted like it was something i did. I offered to pay him for it but he turned it down. Is there anything I could have been doing to cause that type of performance? Tried a 23 laser and it shot out the hole. Here is a pic of the prop.

 

[ROBERT CROSS]

Change venders......Call Hydromotive Todd & Thom won't steer you rong.

 

[Tim Powell]

Ive been tinkering with a 32 BC Performer 3 on my XB21/300xs when conditions allow. So far it has ran a best of 98 @ 5850. Upon further inspection I discovered that my measurements were off and I was still below the pad and less than neutral trim. It was definitely lifting the boat very well and I feel it will run very good on my boat.

I typically run the Hydromotive X-O/B but I also like the Performer 4 as a play prop. The same day that I ran the P3 I also ran the following:

30 Hydromotive X-O/B - 98 @ 5950
30 Bullet Cut Performer 4 - 98 @ 5850
32 Bullet Cut Performer 3 - 98 @ 5850

Again I had the engine too low, 30+ PSI and less than neutral trim.

Previously I ran the 30 X-O/B to 99.0 @ 6150 but that was last fall with a different jackplate configuration and a few other minor things that I changed over the winter.

All of this is with a 36v troller on the nose, full fuel, and all of my gear.

 

[silverbullet02]

What 4 blade would y'all recommend on a xtb with a coned stock 150 turning 5800? Also tried a 25 chopper. It had a 75 yard hole shot and 52 was all I could get out of it level with the pad. Had it re hubed and nothing much changed. A little better holeshot anf no top end. Dealer that I got it from paid to have it done but when nothing changed and i traded it on another prop he got a little pissed about the re hub job and acted like it was something i did. I offered to pay him for it but he turned it down. Is there anything I could have been doing to cause that type of performance? Tried a 23 laser and it shot out the hole. Here is a pic of the prop.

I'd try a 25 trophy plus to get you ballpark. That's what I ran most of the time on my xtb-21 with a 150 Promax.

 

[jeremy hood]

Got a 25 laser 2 hopefully I'll get some seat time and it'll work out.