Props & the Different Mods

[Joe Warren]

Well we are in the mid - summer stretch & Was wanting to open a Topic of Props and the difference in what makes some better than others. Some of us try many different props & sometimes find a better prop that may be the same P/N But it is better prop for the boat? I personally have found to pay very close attention to the leading edge Just as much as the trailing edge... the leading edge can and does suck air onto the prop surface and does determine the top speed you will be running. very small tweaks or bends can help. Strut dept also is very critical in the realtionship of the prop to run at surface level while the boat is in motion. We have a few guys on this board that have a lot of knowledge of the slight difference in making a Sweeet prop. Andy Brown, Marty Davis, Chris Grim, Mark Shouland. Each one of these guys have Built several hundered props that have WON 100`s of races and National titles & Set Records. All have the Respect of the Racing Community on helping a fellow boater on His or Her Quest to GO FAST!!!!!!! Maybe they will Chime in as we go? Each one of the prop tuners have there own special interest in diffferent size boat they like to race and tune on...... Leading Edge, Trailing edge, Total Cup, Cob Cup, Diameter & and back cut or No back cut all do make a Difference. I personally have never seen a boat that could not benifit from a better prop at most any time.................. It is the #1 Tuning TRICK!!!!!

 

[DON MAHER]

Well we are in the mid - summer stretch & Was wanting to open a Topic of Props and the difference in what makes some better than others............... It is the #1 Tuning TRICK!!!!!

DING! DING! GIVE THAT MAN A CIGAR!!!! ^_^

Don

 

[shoboat]

Joe,

We have been testing opening up the leading edge pitch @33% aprox. up the leading edge

with Very Good Results. I will caution you to only open them up .010" at a time and test as you go.

We also have been working on making the cups smaller and boost the leading and center of blade pitches

Up more so they act as a more constant pitched propeller. I think too much pitch progression is not very

Good for performance and tuning the motors. I think our Hydros run and tune better with a more constant load on them.

These are just a few areas that we have been testing and working on recently. John Beardslee just made

me a nice digital pitch gauge that I am starting to use a little more recently. It has been quite a learning

experience using both gauges, but I think the results are getting better with more accurate results. We

recently gained aprox. 3 to 5 MPH on a very well set up twin Crapshooter down in South Florida last

weekend. Let me share a little information from that test session: A .6mm blade length change in diameter

made a 3 MPH gain on top speed ,but it did sacrifice just a little throttle response. We are getting it figured

out quite well now with a lot of great customers giving me back some good videos and quality testing results.

Good Topic,

Mark Sholund

 

[Elias Vazquez]

Props are PARAMOUNT!! in my book.

 

[Samuel Hagan JR]

The only thing with me is I'm learning what I can and reading what I can but I'm more of a hands on person, it's hard for me to comprehend what you guys are talking about without someone showing me. But I'm learning a lot about props. Keep the info coming.

Is there a video anywhere about properly cupping and pitching a prop?

 

[Joe Warren]

Well the base line prop must be obtained 1st for the desired boat and engine combo. Most boats today have a base line prop estabished, but that does not mean the is the only prop that will work. if your Racing a Mono or a Hydro different prop mods apply to both. But it is always best to keep the prop as deep as possible to keep the entry of the prop from Sucking surface air and cavitaing the prop at low & high speed. p.s if you have to raise the strut to get the boat to launch or work for the days set up?? You will trade off Big MPH on top end due to prop Cavitation. You would be better to kill the lift on the trailing edge and push the prop down deeper in the water.

 

[chas terrell]

Joe great topic very helpful man!!! Props can be a VERY difficult area for a lot of us boater especially when it comes to the different modds and tricks you can do to them.I agree with Samuel it would be helpful to see some video tutorials on cupping and such.

 

[Joe Warren]

If your running a Known & Proven boat design and a known mfger. One of the Prop Tuners can get you very close to a Great prop. However Condition of the engine, Pipe length & the ability to read the plug to now begin to tweak the cup on the prop to max speed. Remember the prop is supported by the strut & mainly controls the running dept of the prop. if you must move the strut to help with boat set up not being correct? You will greatly effect the Prop Performance. Nowdays you see a lot of Our props Mono & Hydro that are back cut to kill some lift. This works cause it allows you to adjust the strut down and Keep air off the suction side of the prop. Improving traction in the water.

 

[shoboat]

Joe,

Cupping is only part of the propeller enhancement.

Start looking at the whole picture, the rest of the blade area.

I would reduce the cup on most stock propellers and add some

Center Of Blade Pitch and then add some leading edge pitch if it

was mine.

Thanks,

Mark Sholund

 

[Samuel Hagan JR]

Joe,

Cupping is only part of the propeller enhancement.

Start looking at the whole picture, the rest of the blade area.

I would reduce the cup on most stock propellers and add some

Center Of Blade Pitch and then add some leading edge pitch if it

was mine.

Thanks,

Mark Sholund

I would pay to see a How To Video of prop work. I'm just guessing, and learning right now. I would like to know why the changes I made to the prop made my boat goes faster. That and the proper procedure for cupping a prop blade.

 

[Brian Schymik]

Like Greg, I am lucky to have Alan Elzer do so many props for me. All of my success can be traced back to him. Like Joe said, Props are the number one tuning trick.

My playbook is like this: conservative or even stock motors- more consistency in my experience, 50% nitro- again more consistent, a proven hull, and a great prop. When you find one, get a copy. You will be happy you have a spare when it gets dinged up.

 

[dwilfong]

Lately I have bin paying more attention to the troth as I call it.

Looking at the prop from the tong to the tip and you will see what I am talking about.

If it is strait with no hill or valleys in it the water seams to flow better off the blade.

Also the out side what I call the parabolic curve need to aim the water twards the back side or trailing edge.

Think of it like you are sliding down it what would you fell. If a slide has hump in it you have a bumpy ride and do not keep you but planted on the surface. now a slide that is strait you pick up speed as you go down it then you are kicked out at the bottom.

Kind of a sill way to put it but it gives you a visual you can relate to in real terms.

 

[chas terrell]

If your running a Known & Proven boat design and a known mfger. One of the Prop Tuners can get you very close to a Great prop. However Condition of the engine, Pipe length & the ability to read the plug to now begin to tweak the cup on the prop to max speed. Remember the prop is supported by the strut & mainly controls the running dept of the prop. if you must move the strut to help with boat set up not being correct? You will greatly effect the Prop Performance. Nowdays you see a lot of Our props Mono & Hydro that are back cut to kill some lift. This works cause it allows you to adjust the strut down and Keep air off the suction side of the prop. Improving traction in the water.

Interesting... for along time I wouldn't leave my comfort area with props( which was the octura Xseries) I had absolutely no success in the early days with lifting props modded or not .Honestly, it wasn't until the last 2 season I've become more successful with lifting prop through topics like THIS and physical trial & error.

 

[Tim_Duggan]

......on most stock propellers and add some Center Of Blade Pitch and then add some leading edge pitch if it was mine.

Mark,

I'm curious as to how much COB pitch can be bent in to the more common props and whether you do that first before moving to LE and TE, as the blades would seem to be easier to bend when near an edge. I haven't experimented yet with bending at the COB or LE, just resorted to cutting back the LE to increase the effective LE pitch and /or the diameter to reduce blade area.

Thanks in advance,

Tim

 

[lohring]

You can only increase the total pitch a limited amount by bending since the hub pitch won't change. Even though the part of the blade that produces most of the thrust is the outer 1/3, eventually the central part will start running a negative angle of attack. All types of internal combustion powered SAW hydros are starting to run into pitch limitations. As an example assume an effective pitch (not cup) of 6.5 inches ( 165 mm or a pitch ratio of 2.3 on a 70 mm prop) and a slip of 20%. At 20,000 rpm the speed would be 102 mph. At 25000 rpm the speed would be 128 mph.

These are close to the SAW record speeds of gas hydros and nitro hydros respectively. You can go a little faster if you can get significant power at a higher rpm. We ran 110 mph with around 23,000 rpm but the power was probably 1/2 of the peak. There's a lot more power available at a lower rpm. We just need higher pitch props.

Lohring Miller

 

[Tom Foley]

Everyone is forgetting the number one modification that has the most effect on keeping the best performing props on your boat ......

TURTLE POPULATION CONTROL !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Hydro Junkie]

And here I was, thinking turtles are those little white lane markers used on the freeway :blink:

Tom, are you saying they found a way to use them to mark lanes in the water now too

 

[shoboat]

Tim,

You have to be careful on profiling the leading edge of the propeller. Most are cutting some of the

Leading edge pitch right out of the blades. I measure before I do any profiling to what the Leading edge pitch

is in the stock propeller. How I add Center Of Blade pitch is by taking some of the cup out of the trailing edge first

with my pliers, and then grab the blade in the center and pull back and up at the same time. A lot of measuring until

you get the hang of it. What I find is that when you move the blade around it affects all the numbers but mostly the

Trailing edge cup and center of blade pitch the most. When you start bending the leading edge just remember it does

not take a lot of movement to make a big change in the leading edge pitch measurement. Subtle changes and go test

them and see what they do. Another great thing is to add material to your mandrels on the leading edge side like a shim

and bend them that way. Most propeller work is just patience and measuring time and time again. You get better

at it after a few thousand propellers, it comes easier and easier like anything else. You will start to develop a touch in

bending the blades when you do enough of them, believe me!

Have Fun Testing,

Mark Sholund

 

[Tim_Duggan]

Thank you Mark!