bulldozer prop.

Airboat propeller discussion.
blasterboy#92
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bulldozer prop.

Post by blasterboy#92 »

I've been shopping around for a replacement prop for my boat since I'm repowering it. Don't care about speed, just want that dry running, point and go, burn the hill heavy push...

16' deckover, seating for 6 with cooler and storage. lq4 with cam. 2.09 and 80" water walker with plenty of room to grow. runs but not a hill burner in the least... Going turbo, 750hp and need to get more prop.. plan on keeping the box for now, so a prop that will work at 2450 or higher would be nice.

Been leaning towards the JX 3 blade but im not sure if the R's would be a better fit.

so what does everyone have with a similar setup and how do you like it, what would you change???

Thanks guys

SWAMPHUNTER45
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Re: bulldozer prop.

Post by SWAMPHUNTER45 »

Your leaving meat on the bone with that drive ratio.

Gladesman06
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Re: bulldozer prop.

Post by Gladesman06 »

I couldn't agree with Swamp more. You are leaving A LOT of meat on the bone with that ratio. How much RPM's do you want to spin?

blasterboy#92
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Re: bulldozer prop.

Post by blasterboy#92 »

I agree with you guys as well, I would prefer a 2.38 or a 2.55 but its the box ive got and don't really want to drop the cash on a new one right now. I can get the 750 by 5400.

Also, for the push im looking for should I go with a 4 blade over a 3?

Striker543
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Re: bulldozer prop.

Post by Striker543 »

My experience is 4 blade with a higher gear ratio is much better than 3 blade with less gear. Plus if you go 4 blade you can probably use the same prop when you upgrade your gearbox.

blasterboy#92
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Re: bulldozer prop.

Post by blasterboy#92 »

Striker543 wrote:
Thu Apr 30, 2020 10:26 am
My experience is 4 blade with a higher gear ratio is much better than 3 blade with less gear. Plus if you go 4 blade you can probably use the same prop when you upgrade your gearbox.

That makes sense, and with my power output i should be able to swing a 4 blade with a 2.09. just need to figure out what blade speeds i can safely get away with until i switch. i don't like spinning them past recommended, though i know a bunch of people do.

I think a prop between 2300-2400 would work for both.. it would be on the low side with my 2.09 and the high side if i went to the 2.38

swamper2
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Re: bulldozer prop.

Post by swamper2 »

All depends on how you pitch your blades. You can let her spin or hold her back.
16ft alumitech/406sbc/2.38w/3-80in.R's

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OneBFC
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Re: bulldozer prop.

Post by OneBFC »

As for RPM, I run around 5800 to 5900 with a 2.38 box and swing a 3 blade 80 inch maximus pitched at the "2" mark.

So, that's in the RPM range you are talking about.

You didn't mention which water Walker blade you have but if it's not a maximus you may consider going to 4 of those. I wouldn't trade mine for any other blade and I have tried a very large number of props between 2 and 4 blade configs.

4 blades for sure minimum. If you had more gear I would say 5 blades would work even better. The 6 blade 82 inch maximus setup I tuned last year needed 900+ hp to turn it the right rpm.

That 6 blade was sure nasty though!

Good luck with it!
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy

blasterboy#92
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Re: bulldozer prop.

Post by blasterboy#92 »

swamper2 wrote:
Thu Apr 30, 2020 6:22 pm
All depends on how you pitch your blades. You can let her spin or hold her back.
Yeah but whats the trade off ratio. More pitch is more push but at a lower speed,,, or less pitch more speed, but the speed of the prop makes up for the less pitch but equals out in push???

SWAMPHUNTER45
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Re: bulldozer prop.

Post by SWAMPHUNTER45 »

So you say you can get 750 @ 5500

We will use that as a constant.

At 2.0 that gives a theoretical mechanical advantage twice the input making 1500

At 2.55 that 750 leveraged by ratio can yield a theoretical 1912

When you get to building serious efficient engines and try to add in another 75hp the cost is huge. Often thousands of dollars.

Your leaving a lot of meat on the bone with a 2.0 ratio.

Your platform is a rpm friendly (5400) platform.

You can spin less pitch or blades but if you want push big long wide works.

I have run Sensenich S and JX
My cousin runs WW Maximus

All great blades for push.

blasterboy#92
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Re: bulldozer prop.

Post by blasterboy#92 »

And does anyone know how the NGR blades compare to the JX blades? The NGR's are rated at 2800 so i could still use my box and with a 4 blade and id hope to have enough thrust.

But if i was to go with the jx blades i dont know if I could spin them. My engine is on the lower end of the power level recommended and especially when i can only spin them nearly 5000rpm...

But id rarher get a different box and go with the better prop if there is that big of a difference in props. They dont list the thrust specs on them, just the hp rating.

Thanks guys

SWAMPHUNTER45
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Re: bulldozer prop.

Post by SWAMPHUNTER45 »

The message I will give you is you don't have to spin a blade at its highest safe rpm to get push.

If you wanted to build speed I would say peak your blade speed.

For push you want power, pitch and wide blades.

Where are you located at ?

blasterboy#92
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Re: bulldozer prop.

Post by blasterboy#92 »

SWAMPHUNTER45 wrote:
Thu Apr 30, 2020 9:27 pm
So you say you can get 750 @ 5500

We will use that as a constant.

At 2.0 that gives a theoretical mechanical advantage twice the input making 1500

At 2.55 that 750 leveraged by ratio can yield a theoretical 1912

When you get to building serious efficient engines and try to add in another 75hp the cost is huge. Often thousands of dollars.

Your leaving a lot of meat on the bone with a 2.0 ratio.

Your platform is a rpm friendly (5400) platform.

You can spin less pitch or blades but if you want push big long wide works.

I have run Sensenich S and JX
My cousin runs WW Maximus

All great blades for push.
I didnt see the reply before my last post. Appreciate the reply.

As much as id like to try i know your right. I dont think ill be able to make sufficient hp with my current box and any of the 14+ wide blades at the low 2200ish rpm, with out some more upgrades and more boost.

Yeah the JR series blades seem like the best fit for the 2500RPM wise but i believe the NGR's would work aswell. Just not sure which would have more thrust of the two given they are the same width but different designs.

blasterboy#92
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Re: bulldozer prop.

Post by blasterboy#92 »

SWAMPHUNTER45 wrote:
Thu Apr 30, 2020 10:02 pm
The message I will give you is you don't have to spin a blade at its highest safe rpm to get push.

If you wanted to build speed I would say peak your blade speed.

For push you want power, pitch and wide blades.

Where are you located at ?
Gotcha. Yeah the speed im not worried about, its the push. I dont want to get stuck.

Im in marion county. Actually about 45min from GT0. I just prefer the opinion of many vs the opinions of people selling stuff. Not that they dont know their stuff,,, and im sure they would be willing to give me plenty of advice. I was just looking for other perspectives

blasterboy#92
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Re: bulldozer prop.

Post by blasterboy#92 »

OneBFC wrote:
Thu Apr 30, 2020 7:25 pm
As for RPM, I run around 5800 to 5900 with a 2.38 box and swing a 3 blade 80 inch maximus pitched at the "2" mark.

So, that's in the RPM range you are talking about.

You didn't mention which water Walker blade you have but if it's not a maximus you may consider going to 4 of those. I wouldn't trade mine for any other blade and I have tried a very large number of props between 2 and 4 blade configs.

4 blades for sure minimum. If you had more gear I would say 5 blades would work even better. The 6 blade 82 inch maximus setup I tuned last year needed 900+ hp to turn it the right rpm.

That 6 blade was sure nasty though!

Good luck with it!
I didn't see your reply either. Damn phone.

Its actually a falcon series. Water walkers site doesnt list the info on the maximus anymore so i wasnt sure of the rpm ranges. I was assuming around the 2200 mark like the rest of the wide blades out there. But if they are closer to the 2500 mark that sounds like it would be my best option.

My buddy runs a 3 blade maximum behind a worked 440 and a 2.38 and it does pretty well with his barge of a boat.

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Slidin Gator
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Re: bulldozer prop.

Post by Slidin Gator »

Blaster,

If this is what you want:
blasterboy#92 wrote:
Thu Apr 30, 2020 10:20 pm
Yeah the speed im not worried about, its the push. I dont want to get stuck.
Then this is what you need to listen to:
SWAMPHUNTER45 wrote:
Thu Apr 30, 2020 10:02 pm
For push you want power, pitch and wide blades.
At the moment, you are heading down this path:
SWAMPHUNTER45 wrote:
Thu Apr 30, 2020 10:02 pm
If you wanted to build speed I would say peak your blade speed.
At a given power level, prop speed = speed, prop torque = push. I think you got a boat that needs some push:
blasterboy#92 wrote:
Wed Apr 29, 2020 10:03 pm
16' deckover, seating for 6 with cooler and storage.
You are wasting money hot roding the motor and a whole new prop without spending for the right gear. When you do decide to upgrade the gear, you will have to double down on more prop too.

Spend your turbo money on more gear & pitch first to see if that doesn't make you grin. :albino:
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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OneBFC
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Re: bulldozer prop.

Post by OneBFC »

Well, 4 falcons were equal to 3 maximus blades in my tests. The 4 falcons had a little steeper curve from a required power perspective and loaded my engine in an rpm range I didn't have enough fuel to cover so I went back to 3 max setup without losing any thrust. Cruise rpm was just slightly higher with 3 max vs 4 falcon.

Whatever you end up with, 4 blades for sure. Oh, and I am running the max blades a little higher than their official rating. Something to keep in mind. I haven't had any issues with it, but, talk with them before making a final decision to use them at the rpm you are wanting to.
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy

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Re: bulldozer prop.

Post by One Eyed Gator »

Each blade has a sweet spot for tip speed in mph. To me that comes from matching engine rpm, gear ratio and blade length with enough pitch to be efficient.

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digginfool
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Re: bulldozer prop.

Post by digginfool »

SWAMPHUNTER45 wrote:
Thu Apr 30, 2020 9:27 pm
So you say you can get 750 @ 5500

We will use that as a constant.

At 2.0 that gives a theoretical mechanical advantage twice the input making 1500

At 2.55 that 750 leveraged by ratio can yield a theoretical 1912

When you get to building serious efficient engines and try to add in another 75hp the cost is huge. Often thousands of dollars.

Your leaving a lot of meat on the bone with a 2.0 ratio.

Your platform is a rpm friendly (5400) platform.

You can spin less pitch or blades but if you want push big long wide works.

I have run Sensenich S and JX
My cousin runs WW Maximus

All great blades for push.
Swamp, the gear is a torque multiplier, not a HP multiplier. Now that's not to say he wouldn't make something close to 750 ft-lbs if he can make 750 HP at 5,400 RPM but he hasn't said what his torque will be, only his goal of HP.
“When plunder becomes a way of life for a group of men living together in society, they create for themselves in the course of time a legal system that authorizes it and a moral code that glorifies it” - Bastiat

SWAMPHUNTER45
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Re: bulldozer prop.

Post by SWAMPHUNTER45 »

Dear DiggingFool

I avoid the word TORQUE on Southern Airboat as for the past 5 years the HORSEPOWER BOYS have preeched that "torque aint shizt" and horsepower is all that matters. So to appease the HP crew and keep peace on the thread the word TORQUE was removed from my dictionary.

But like giving a recovered alcoholic a drink..... you DIGGIN have opened back up the TORQUE discussion!

In rebuttal running a 2.0 drive on a boat that needs beast mode push is leaving a lot of power (TORQUE) untapped. The only reason someone would use that ratio in a planned build would be if their engine was not capable of spinning enough crankshaft rpm to put the prop in a usable blade rpm range. So as SlidinGator outlined your dollar cost to power yield may best be gained in a gear ratio change.


How does that big Center Console boat ride?

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Re: bulldozer prop.

Post by kwanjangnihm »

Image
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

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Slidin Gator
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Re: bulldozer prop.

Post by Slidin Gator »

SWAMPHUNTER45 wrote:
Fri May 01, 2020 10:15 am
So as SlidinGator outlined your dollar cost to power yield may best be gained in a gear ratio change.
Just one correction Swamp, "dollar to thrust (vs power) yield" (in this case) appears to be highest for the gear change, that is where the low hanging fruit lies.


I'm a fan of TORQUE, but a bit hard of hearing, so when I heard our president designate TORQUE an essential protein and ordered all TORQUE producers back to work, I thought Awesome :cheers:

So, say we got a quota of 750 lbs of PORK/day, does it matter is we slaughter 7.5x of the 100 lb reference hogs each day, or can we fill the quota with 3.75x 200 lb milk sows? Which one gives more yield?

New math is weird, but you see where I am coming from.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

SWAMPHUNTER45
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Re: bulldozer prop.

Post by SWAMPHUNTER45 »

If we run out of Torque we can always eat the Horsepower!

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Slidin Gator
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Re: bulldozer prop.

Post by Slidin Gator »

You can, but HP goes rancid. It happens when you take Torque and let it sit for some time.
I still think I-10 is the Mason Dixon line.
2013 Mike Stossel Boats, 13' x 7' deck over, IO-540, 74" NGQ less winglets.

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kwanjangnihm
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Re: bulldozer prop.

Post by kwanjangnihm »

all AC guys know that less meat on the bone equates to a better torque slider :thumbleft:
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

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