Are fewer blades always 'faster' than more blades?

[Dhadley]

Re: Are fewer blades always 'faster' than more blades?

The fastest prop on my flats boat is a 4 blade Turbo. And it's the best cruise prop too. My 3 blade Turbo runs almost as good and holds the bow higher at lower rpm (great in rough water). Most of the performance boats (flats and bass) we prop out are fastest with a 4 blade. A lot of the fastest circle race boats run 4 blade props.

However, you have to consider application, design and set up in each case. A decent 3 or 4 blade set up properly will always be better than the best 3 or 4 blade prop thats improperly set up.

 

[Frank Acampora]

Re: Are fewer blades always 'faster' than more blades?

Well, Phil: back to your comment on not understanding the need for a couple of MPH more--- I have a little 14 footer that does 60 MPH. I only use it a couple of times a season. However, with this hull it is the experimentation and tinkering to get it to go faster that motivates me. My goal is to get it to 65. Not so I can beat anyone but just for the satisfaction of improving performance. To me, that's a valid reason to want more speed.

 

[V153]

Re: Are fewer blades always 'faster' than more blades?

Sorry to chime in so late. If you're in quest of top end speed the simple answer to your question is yes.

However if top speed is not your objective please refer to the previous posts ...

 

[Philster]

Re: Are fewer blades always 'faster' than more blades?

Well, Phil: back to your comment on not understanding the need for a couple of MPH more--- I have a little 14 footer that does 60 MPH. I only use it a couple of times a season. However, with this hull it is the experimentation and tinkering to get it to go faster that motivates me. My goal is to get it to 65. Not so I can beat anyone but just for the satisfaction of improving performance. To me, that's a valid reason to want more speed.

Oh, I hear ya. In that case, it's a specialized interest, but I think there becomes a fixation with top speed for many boaters that doesn't really make any sense. I know; I know... coming from a guy with a performance boat. :facepalm:

 

[halfmoa]

Re: Are fewer blades always 'faster' than more blades?

Oh, I hear ya. In that case, it's a specialized interest, but I think there becomes a fixation with top speed for many boaters that doesn't really make any sense. I know; I know... coming from a guy with a performance boat. :facepalm:

I never did understand spending cash in excess of 1K for a MPH or two. When I'm on the water 30MPH feels like 50MPH in a passenger car. A project boat with a quest for top speed I can understand. It's a hobby, a quest, a fixation, something that keeps you up at night. But I've got a friend that spent 1500 bucks on some high-performance-promising pipe dream of a prop for an extra 3MPH. His boat went 70 as is. He bought a GPS just to ensure he was getting the extra 3MPH he paid for. IF YOU CAN'T TELL, DID IT MATTER?!?!? Give me $500 and I'll lie to you and tell you that you're going 3MPH faster...it's cheaper anyway.

Back when I was still drag racing we had a saying for the guys who had a 4 second car but couldn't keep it in a straight line or even qualify for their license...more money than brains.

 

[Texasmark]

Re: Are fewer blades always 'faster' than more blades?

Well, Phil: back to your comment on not understanding the need for a couple of MPH more--- I have a little 14 footer that does 60 MPH. I only use it a couple of times a season. However, with this hull it is the experimentation and tinkering to get it to go faster that motivates me. My goal is to get it to 65. Not so I can beat anyone but just for the satisfaction of improving performance. To me, that's a valid reason to want more speed.

Well Frank keep it up. I'm proud that you have found that hobby and enjoy it. My current hobby is web surfing sites like iboats and others and what you are doing would surely be more fun. I spend most all of every day out in my shop and dream up things to create daily. All my stuff is up and running and some days I'm so bored (without something constructive to do) I even sweep the floor.......geez, what a waste of retirement time. Grin. I even braved the weather and low water levels and took my little toy out in 20-25 mph winds yesterday. Kept me on the leeward side of the lake and I did scratch my pet prop on a cinder block submerged close to the ramp, but it was fine and my sweetie was sitting next to me just hanging on to me and having a blast.

Mark

 

[Frank Acampora]

Re: Are fewer blades always 'faster' than more blades?



And Phil: Here are a couple of photos of my 10 foot tunnel hull. Notice that this little puppy---no, not the chick magnet, the boat--has a two blade bronze prop on it. The reason is that the only three blades I could find for this engine went up to 13 pitch and the two blade is 15, then I cupped it. This prop is from 1968, Michigan #AJ something, 10 1/2 diam X 15 pitch--I bought it new-- and back then a racing prop was two blade bronze.

Like stated before about hydroplanes, She starts off bow high and I need to lean way over the steering wheel. When the boat finally breaks over into plane, she gives a sharp snap (torque?) to the starboard. I immediately correct then sit and she is stable.

This boat started with a 15 HP engine and topped out at 20 MPH--she planes at 18. Less than that and she will drop off. With constant tinkering and constantly larger engines I worked her up to 45. More modifications to come. Need to play with engine height as soon as I get a low water pick-up on the engine. Then maybe I will see some serious speed.

Mark: I am also retired a year December 31 and with remodeling my house and the numerous boat and engine projects I am busier than when I was working.

 

[Philster]

Re: Are fewer blades always 'faster' than more blades?

Sweet!

I see a problem: You and that engine cowling are a big air break!

 

[Silver Eagle]

Re: Are fewer blades always 'faster' than more blades?

I tried a four blade prop a few years ago on a 21 ft Bow rider. It was an Arriva with a 230 hp I/O with a Alpha one out drive. I used it for about two months. Then I went back to the three blade prop. It seemed to pull to much to the right and it took longer to get on Plane,and there was a lot of Vibration at mid range.

 

[Chinewalker]

Re: Are fewer blades always 'faster' than more blades?

More blades CAN be faster in some cases. As a for instance, some of the racing guys are running 4 blade props, BUT they're surfacing, running approximately half out of the water. The theory behind this is you can jack the motor up to the point where one blade is always in the water. Doing this with two blades resulted in blade slap and some funny handling characteristics. Three blades helped the handling. Four blades takes it a step further. Each set-up allowed higher propshaft heights. Problem was, as the propshaft got higher, so did the skeg, resulting in prop walk and loss of control surface - you'd be surprised how much directional stability comes from that 8-10 or so square inches under the bullet! Not as much of an issue in a modified class where you can add depth to the skeg, but the stockers (where no modification is allowed) ended up getting a height limit imposed where the propshaft centerline was no less than 3/4" below the bottom of the boat. Stocks are also limited to 3 blade props to help level the field. Some of the mod guys run 5-blades...

 

[Tail_Gunner]

Re: Are fewer blades always 'faster' than more blades?

Yeah, so I think what'll I will do from now on is tell 'em to try it out and be ready to switch back to the old prop if the new one doesn't cut it.

I never understand all this grief over a couple of miles an hour (I know; I know... from a guy with high performance boats). I could understand if there was an issue that should be addressed, but does it matter if a center console tops out at 44 or 46? Isn't the low-end and mid-range performance just 99% of the issue?

Anyway, I digress... but I'll be sure to report on the Checkmate top speed...

I second that thought...A good 4blade with overall lift is a kick in tha pants in midrange punch. I have noticed that boats above 4000 lbs dont always respond as well to them but then again 4000lbws is a lot of boat.And your hull needs to compliment the 4 blade design in my particular case i have enough midrange punch the boat can literllay hop on top of a 2' swell or hard throttle at 20 to 40 it acts like a heavy 4 barrel carb boosting things up...always good for a grin or two.

As to speed yes i do lose 2 mph..who cares its simple to prop up two but that last's generally for a day or two and back to the 4 blade..Again its very important to get a prop that accentuates your hull.