Why so much torque roll??

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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GeeLeDouche
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Why so much torque roll??

Post by GeeLeDouche »

I was riding with a good friend of mine the other day in his 14x7 (Panther) hull with 2 side by side rear seats and a front bench seat (Florida style) boat with a 383 stroker, CH3 2.0 with 3 R blades. while riding the other day I noticed a HUGE amount of torque roll, mostly when not on plane and in deep water. Like,, the entire starboard side of the boat would dip so hard in deep water I thought we were going to tip the sucker over, and we would take on a few gallons of water a couple different times because of it. This cant be normal can it? it was enough to scare me pretty good.. I was looking at the prop and it spins the opposite direction of the torque roll which doesn't make sense to me. I cant for the life of me figure out why its so bad. on my rig I have a 2.3 CH3 spinning 3 r blades and it doesn't have any noticeable torque roll, but my boat is a 16x8 Utah style hull.

Any thoughts on why this particular rig has so much torque roll when we accelerate to get on plane from deep water? is it the size of the boat? is it the belt reduction? Thanks guys
Last edited by GeeLeDouche on Tue Nov 04, 2014 11:39 am, edited 2 times in total.
16x8 Utah style hull With a Waterthunder motor W/ 2.3 CH3 reduction swinging a 3 blade 78" R.
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17-51 Legend craft w/pods pushed by a MB HD7000

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digginfool
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Re: Why so much torque roll??

Post by digginfool »

The direction of the roll is correct; a belt drive turns the prop the same direction as the engine turns. The torque is opposite the direction of rotation of the prop due to the laws of physics; for every action, there is an equal and opposite reaction. The shape of the bottom of the hull, weight distribution, width of hull, power of engine and pitch of prop all have an effect on how much roll you will experience. The fact that you are taking on water from acceleration would make me believe how deep are the sides of the boat, how wide the boat is and weight distribution as the biggest contributors to the issue. Obviously, you can't change width or depth without changing hulls so I would look at weight first.
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GeeLeDouche
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Re: Why so much torque roll??

Post by GeeLeDouche »

Thanks for the reply DF. :)

Its actually a fair deep hull. I mean, deeper than my Utah style. Your probably right about the weight distribution. Im a fairly large fella, much larger than my hunting companion that day, and I was sitting on the side that was rolling so that may have had something to do with it. It was definitely a "pucker moment" in life a couple times that day. I just couldn't believe that it would roll that much and dip that deep when accelerating!

ps- the hull looks identical to this one but the seating and motor are obviously different. http://www.nauticexpo.com/prod/panther/ ... 58624.html
16x8 Utah style hull With a Waterthunder motor W/ 2.3 CH3 reduction swinging a 3 blade 78" R.
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17-51 Legend craft w/pods pushed by a MB HD7000

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elChupacarburetor
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Re: Why so much torque roll??

Post by elChupacarburetor »

My boat has a lot of torque roll and I've been told a major factor is the size of your prop. And that makes sense. It's a simple machine with the fulcrum being the center of the spinner. If your prop is longer the resistance out at the end creates a more pronounced turning tendency.

So it makes sense that if you shortened the prop and added pitch you might reduce the roll.

I'm also in the process of repositioning a few things in the boat to help balance it at the speeds I spend most of my time at.
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scottyroll
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Re: Why so much torque roll??

Post by scottyroll »

My previous boat had some bad torque roll and would probably roll over in the water if I didn't work the stick to level it out - As you know it's definitely not a desirable experience. 13'6" x 7' and side by seating and a big wide 80" prop is what I had. I think side by side seating is better suited for boat that is at least 8ft wide and that's why I'm running inline seating on my new build.
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One Eyed Gator
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Re: Why so much torque roll??

Post by One Eyed Gator »

If it was the older style panther with the round side. Any of the round sided hull have a seem to have more torque roll than a new flatter style hull. My buddy has a 14' airgator with a round bottom and it will scare the crap out of you but he has gotten the hang of driving it for a while. I have almost dump it a few times. Good thing it's a deckover lol.

The glades style boat like a Kline with a round bottom is another boat that will scare you and take some time to get use to driving it.

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Re: Why so much torque roll??

Post by :) »

The older panthers were kinda rounded at the bottom and sides, where they meet.
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captain chad
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Re: Why so much torque roll??

Post by captain chad »

All Older round sided Panther boats torque roll bad. It's a trait of those hulls.
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Re: Why so much torque roll??

Post by OLD MAN JONES »

why so much torque roll?

U got 1 bad a$$ motor !!!! :toothy7: :thumbleft:
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Deano
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Re: Why so much torque roll??

Post by Deano »

Having a seven foot beam is generally a good thing when considering cargo space. However, when the discussion has to do with torque roll and/or lateral stability, the much more relevant measurement is the width of the flat section of the planning surface. Seven feet (or more) of flat bottom will be comparatively stable, whereas five feet (or less) of flat bottom will be very canoe like in comparison. And as OMJ points out, the badder your engine is, the more pronounced this effect will be when you stab it.

There is a reason why on drag boats, the flat bottom measures nearly as wide as it does at the gunwales.
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