Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

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sarros2004
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Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby sarros2004 » Sun Aug 11, 2019 11:54 am

Hi all!

Thanks, largely to contributors on this site, I have officially been able to begin water trials in my rig. After battling normal setup, fuel, ecm issues; and being a complete beginner to airboats, I have taken my rig out now for a few trips. I am becoming more comfortable with handling and driving characteristics. I have questions regarding power out po ut and staying on plane.

The boat is an aluminum 13.5' Airgator,
The true flat of the hull measures 44".
Including the first very shallow angle widths of the hull (which are almost flat); adjacent to the true flat , total flat width is a out 5 ft.
Motor is LS2 6.0, fuel injected 500-600 horsepower
Rotator 2.37 gear box
80" Sensenich R series 3 blade.
40 gallon fuel cell (full)
Stainless rigging and cage for 4 people in fat man seats
2 batteries

I currently have the prop pitched around 2 or just above. Max rpm on the trailer is about 5100. On the water maybe 5200-5300.

Ir runs the hill like a beast. I have not found anything any material yet it will not move from a dead stop on.

On the water however, to stay in plane in deep water requires about 4100-4200 rpm. This seems a bit high to me. I found one post on here that seems to coroborate the this a high rpm for plane, but it was for a larger boat.

My questions are:

Is this normal?

If not, is it high?

Can I bring the on plane rpm down with just a pitch change?

Do I need more or less pitch?

If not with pitch, I'm thinking I must go with a lower ratio like a 2:1 to the plane rpm down?

General thought? Comments?

Thanks in advance for any input.

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OneBFC
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby OneBFC » Sun Aug 11, 2019 12:33 pm

Congrats on getting your boat finished!

Now, unfortunately, you are over estimating the amount of power your engine is producing by quite a bit. A 6.0 isn't going to make 500+hp at 5100 RPM. Let alone anywhere near 600. I would estimate in the 425 to 450 range at the crank but builds vary so your engine supplier should be able to tell you.

That aside, the high rpm required to stay on plane is indicative of a heavy boat and / or restrictive cage and rigging.

Lowering weight is difficult to do once the boat is built and "done". So, you are left with making sure you don't have restrictive cage setup. Things like tight spaced wire, pan cake style cages or, the worst imo, expanded metal on your cage instead of wire.

Lastly, if weight is high and rigging can't be changed or is already deemed not restrictive, then you really only have two options.

More power or a larger diameter prop with less pitch.

The larger prop route will make your throttle response less crisp (less snap) and will lower your top speed as well. You have to balance how little pitch you end up with because you can wind up with a very inefficient prop if you go too low and end up no better than you are now. If you are pitched at the 2 mark or less right now, more prop may not be the best route to consider.

More power is a no brainer but will have its own baggage. a higher fuel bill, lower reliability (but this can be mitigated) and most of the time louder operation.

Basic rule to follow is about 4 to 6lbs of loaded boat weight to available prop shaft horsepower. This will give you a good performance experience.

Anyway, none of that is likely what you want to hear about now but it is what it is. I hope you find a solution that suits you.

Best of luck!
-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

unforgiven11B
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby unforgiven11B » Mon Aug 12, 2019 9:15 am

I run a 16x8 Diamondback 6.0L (Lq4 base) PCM/Levitator, ch3 2:1 belt box, 80”K series (12”)wide cruises at 3400-3500, WOT 5500ish. And only 365ish HP. I would say your a little high on rpm.

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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby Rich Andrews » Mon Aug 12, 2019 9:18 am

S Blades might work here?
I'll have my Manatee burger medium please...just say NObama

14x8 deckover FELBER 397ci.. HP ???..just stay back!!

LOHA is AHOL backwards

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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby Coastslider » Mon Aug 12, 2019 6:06 pm

When your on plane how does the hull feel compared to the water line ? Does it feel level or like the rear of the boat is sitting down in the water ? Sounds like a lot of throttle to get on plane possibly cause the rear is dragging. Maybe move weight towards front of boat to see if anything changes. I moved my fuel tank forward 3ft due to similar situation and made a huge difference.

sarros2004
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby sarros2004 » Mon Aug 12, 2019 7:29 pm

High all,

Thanks for the feed back.

One bfc I agree with your hp assessment. 500 - 600 is just an estimate from an experienced tuner that has plenty if experience with dyno testing and similar setups. But absolutely, his numbers were in 6k rpm range. (And I never saw the printouts myself) Never really though much about the rpm cap limiting power, and is an excellent point. It may be well in the hp range you suggest. That being said the cam is a customer grind and spec for torque at lower rpms.

Larger prop is not an option, the 80' maxes the cage out now. Cage design to me seems pretty open, though it is the 3/4 deal (half pancake, but covering exhaust and headers.)

Rigging weight seems about as much as any other boat, though this set up for 4 people and has a a 40 gallon cell.

Unforgiven and Rich: R vs K bs S blades????? Which is widest/ differences? I was considering a gear change. Maybe stepping down to a 2:1 might be an option.

Coast slider, I dont really have a feel for level yet. The whole rig to me appears to sag in the back when on the water, and it does feel like it elevates up to plane, but I dont know a out "level" but I have little experience running it. I'll pay more attention on my next outing.

I believe ill try adding a little pitch first. I can sacrifice some of the hill burning power. I did run it on a trailer at one point pitched to 3, and could get 4500 rpms out of it. But never tried it on the ground or water.

I'll also look into shifting some of the weight, which I was planning on any way to help with torque roll. Both pitch and weight shift are low cost items to check.

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OneBFC
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby OneBFC » Mon Aug 12, 2019 8:28 pm

Add a 4th blade and switch to more gear, not less. A 2.68 with 4 blades will likely get what you need and not have to give up on anything.

Sure, adding pitch will of course lower cruise rpm. But you will lose max thrust more than likely. Will you lose too much? Only you can say that.

So, your plan is sound. Try some pitch and see how you like it.

Adding a fourth blade without changing gears is also an option. that you can try incrementally before committing to a gear change. Likely a 4th blade will bring your pitch to near the 1 to 1.5 mark (near minimum), but, will likely help low rpm thrust considerably. It's the same as adding a longer prop in reality (roughly).

R blades are solid performers and very common. You are likely to find a 4th blade and a hub used if you keep a look out.

Of course I would recommend a 4 blade 80 inch "Fat Maximus" from Water Walker, but everyone had their preferred setup. A "Fat" Maximus, or Fat Max as I like to call it, is Maximus blade that had been cut down and then put into a long hub. This gets the tip very wide and let me tell you, it pushes extremely well. No other blade on the market has the airfoil shape like a Maximus does. It has a huge amount of cup as you move toward the root of the blade.

Anyway, like I said, R blades are great too so stick with those until you start considering a 4 blade setup. Then perhaps give Andrew at Water Walker a call and see what he says before you pull the trigger on anything else.

My little tiny engine manages to produce low to mid 1500lbs with the Max blades. That speaks for itself imo.


Lastly, all of this advice is predicated on the assumption that your cam doesn't max out engine power below 5500. If it does, then you obviously need to keep the rpm below peak Hp. Size gear ratio accordingly while keeping pitch and blade rpms within design windows.

Again, good luck!
-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

Striker543
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby Striker543 » Mon Aug 12, 2019 10:25 pm

Russ,

What do you think about a wider hull? I read somewhere he has less than 4’ of planing bottom. Wouldn’t such a narrow hull require more power than an 8’ hull to keep on a plane?

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OneBFC
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby OneBFC » Tue Aug 13, 2019 6:34 am

Striker543 wrote:Russ,

What do you think about a wider hull? I read somewhere he has less than 4’ of planing bottom. Wouldn’t such a narrow hull require more power than an 8’ hull to keep on a plane?


Absolutely. Though I am unaware of way to add beam to a boat after the hull has been built.

Excellent point for anyone reading this thread to consider though.
-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

One Eyed Gator
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby One Eyed Gator » Tue Aug 13, 2019 7:09 am

Sounds like the round sided airgator hull. Very narrow running bottom but a beast on the hill.

I helped a buddy built a similar hull with 5.3 2.55 box and 80" maximus blades. It will run across anything but takes about 3800 or 4000 to be on plane if we are loaded down for fishing the gulf for a day. His hull is a heavy deckover and fairly high rigging, torque roll will scare the crap out of you lol.
Last edited by One Eyed Gator on Wed Aug 14, 2019 7:22 am, edited 1 time in total.

Striker543
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby Striker543 » Tue Aug 13, 2019 8:58 am

OneBFC wrote:
Striker543 wrote:Russ,

What do you think about a wider hull? I read somewhere he has less than 4’ of planing bottom. Wouldn’t such a narrow hull require more power than an 8’ hull to keep on a plane?


Absolutely. Though I am unaware of way to add beam to a boat after the hull has been built.

Excellent point for anyone reading this thread to consider though.


True, although if stringers are the same a hull swap wouldn’t be too complicated, although he would likely need to build a new cage for a wider hull.

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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby Coastslider » Tue Aug 13, 2019 2:34 pm

The wider hull was what I meant with my comment. My boat is rounded in the back and is narrowest at the transom. Moved the weight forward some and it freed up and stayed on plane easier. Cam rpm to power would be very helpful also

sarros2004
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby sarros2004 » Tue Aug 13, 2019 10:40 pm

All good info. I plan on changing the pitch this weekend to see what she does.

Everything above are great options, other than changing the hull. I may build another boat in the future with a wider hull, but this is one is sentimental to me.

Pitch first, then I'll update yall. If I end up changing ratios, I may look at swapping it to a belt drive to get the torque roll going towards the right side.

One eye, you are correct it is a round hull Airgator.

Like I say I'll post yall with an update after I try a couple things.

Coast slider, I'll see if I can dig up the cam specs.

Thanks to all.

sarros2004
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Re: Help Staying on plane. LS2 6.0, rotator 2.37, 80" Sensinich R

Postby sarros2004 » Sat Aug 17, 2019 7:54 pm

SOLUTION FOUND. HAHAHAHAHA!!!

Funny how simple things are sometimes......so I go out this afternoon with a plan. Add 2 degrees of pitch and see how she does. Not gonna lie, had some fears and worries about having to reinvent the wheel if this did not work.

Anyway I upped the pitch 2 degrees as planned, waited for the rain to stop and dropped it off the trailer. Watched the RPM as I was taking, off and noticed she smacked 6k.

"???????? .......Thats not right....I have done multiple wide opens and know she caps about 5200." Hit the gas again, this time above 6k
"........??????......WTF?"

Then I noticed, shes idling at 2K. I listen to the motor....."that is not 2000 rpms."

Then it hits me, the RPM gauge is crooked compared to the others. A little further examination revealed that the gauge face had slipped. and could move inside the gauge housing. When you raised the throttle you could actually see it rotate.The needle would push it a little further around clockwise, throwing my rpms readings off by about 1000.

So about 10 minutes of tinkering and several f-bombs later, I had the gauge apart, the face plate corrected, and checked for accuracy using HP tuners scanner software. The worst part was the little gasket between the acrylic lens and the gauge housing, it is paper thin and reminds me very much of a rubber band. With it in place, all it required was a little extra "snug" on the bezel that holds everything together and she was working fine.

With the new pitch adjustment she caps right around 5k, or a pinch before, and cruise on plane is right around 3200.


Now on to battling torque roll.........

Thank you all for the input.


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