Runners on hull?

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Jssflyer
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Runners on hull?

Post by Jssflyer » Sun Nov 18, 2018 12:05 pm

Hello, newbie here.
Do y’all use runners on snow in the winters? I don’t have any on my mini and it’s hard to go in the same direction for more than a few feet. I am planning on putting a couple of 1” wide uhmw runners the length of the hull, to see if that works. It’s generally what you do with any kind of sled or anything that usually goes on snow.
Any input appreciated, thanks!
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F0zzy2
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Re: Runners on hull?

Post by F0zzy2 » Mon Nov 19, 2018 7:46 pm

None of the guys I know run a runner.
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Slidin Gator
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Re: Runners on hull?

Post by Slidin Gator » Mon Nov 19, 2018 9:03 pm

Jss,

I have never run an airboat on snow, you can figure that out from my signature. But in my opinion, the issue you are having is a function of a hull shaped like a wedge, narrow up front, when you want the wide end up front. Triumph tried to sell that as the shape of things to come, but they were wrong.

Add in a weight center up forward and the problem exaggerates. A wide nose with narrower rear makes the whole thing track well. As it is, you hit the gas and your hull wants to dig and roll, Port or Stbd. It has to be squirrely on the rudder.

Just look at the shapes of snow ski's these days, fatter up front and you turn by putting your weight forward. Same thing is happening here, except it is skinnier up front, even worse. In the old days, snow skis were pretty straight and you turned by putting your weight on the rear and praying you didn't bust a@@ backwards. You are beyond old school here.

#1, pitch the prop to blow up at the rear, you need all that you can get there. Worst case it will have trouble planning and porpoise at speed on water, not a key issue right now. Keep pitching it up until things improve or it won't move!

#2, You may end up needing runners to make this hull handle decent. Unfortunately, that is going to kill much of the advantage of having an airboat. Try some 1/2" UHMW (Poly) strips on top of the poly you already have. Try 3x, 1 center and 1 each just on the nose edges and straight back.

#3, you have all winter to play with different shapes of UHMW before you build hull #2. Try some ski's outboard up front...

#4, your a smart a&&, fix it with software, that stuff weighs nothing.

That said, hit the water first/now if you can, just to have that experience before it's frozen solid up there and we are thanking God for the nice comfortable weather. #5, I'm not Cuban, but I do normally fail the Wet foot/Dry foot test.
I grew up thinking I-10 was the Mason Dixon line.
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Jssflyer
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Re: Runners on hull?

Post by Jssflyer » Mon Nov 19, 2018 10:31 pm

Hi fizzy and gator,
Thanks for the replies.
#6 never went north of I-10 till I was 17.all those people are crazy!
#5 . Just messin with you gator, as I figured you were messing with me on your last post.
#4 don’t hav the software for hull design, usually just smoke a bowl and figure it out.
#3 roger that, lot of time to build in the winter...farmings a good job if you like building stuff.
#2 I’m hoping I only need and or want the runners in the winter. All sleds that you tow behind your snowmobile have runners here.. it keeps them from sliding sideways down the slope while your towing it. Hell, the snowmobiles have carbide runners on the bottom.
#1 right now I have 1.5* up at the engine mount. Prop going up towards the rear. I can feel it digging the nose in when I apply throttle. On a normal airboat, this would usually make the nose pivot through the center of gravity lifting the nose.
I believe that with the wedge shape, the point of drag( widest part of hull, far rear) is overcoming the C.O.G. And acting like a drag on the thrust line, shoving the nose down. It’s not horrible, And I feel I still have decent performance. But it definitely feels like the power is hunting for a direction to go.
( I will be trying the boat on flat , smooth ice tomorrow and hopefully have better results. Frozen lake, big, flat open sliding)
The first few trials have been on bumpy, plowed fields, brush, Farm land. Every time I hit a bump or slope I get redirected. The mini being so light and with such a short wheel base, I just get bumped around. Anything I bump into is frozen solid and doesn’t move.i don’t intend to run the boat on really bumpy stuff. It’s the closest ground around. And if i can break it here, it’s much easier than out in the field.
P.s...I also am very new trying to pilot this bad boy. Will take some hours before I can get used to the stick and be in front of the boat and not catching up. I suspect a full 60% of my steering is that. As I can see if I was ahead of the boat I would anticipate what was going to happen.

Thanks for the replies, guys, appreciate it.

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Runners on hull?

Post by bkmail » Mon Nov 19, 2018 11:55 pm

No, its cause your hull is so short.
Ice is terrible to run. Get sideways a bit and smack something solid and your now sideways or upside down with a prop-strike, etc... Add a set of uhmw strakes on the hull like your suggesting and your increasing your odds of flipping it. Iwould NOT recommend running on ice.
Be careful.......
Bk


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Re: Runners on hull?

Post by Slidin Gator » Mon Nov 19, 2018 11:56 pm

Jssflyer wrote: #1 right now I have 1.5* up at the engine mount. Prop going up towards the rear. I can feel it digging the nose in when I apply throttle..
This is what I expected and what several have pointed out. Again, you need a butt load of pitch up on this hull.
Jssflyer wrote: On a normal airboat, this would usually make the nose pivot through the center of gravity lifting the nose.
This is not correct. The thrust line moment makes the boat try to nose down, moving the center of vertical force (combination of CG and thrust moment resistance) further forward. It depends on your line of thrust, but at 1.5 degree I am pretty sure your line of thrust is forward of the CG, therefore pushing the nose down further towards the bow.

This is why I am telling you to pitch it way up, put the thrust line behind your fat a$$ mouth and maybe it will get up and run.
Jssflyer wrote: I believe that with the wedge shape, the point of drag( widest part of hull, far rear) is overcoming the C.O.G. And acting like a drag on the thrust line, shoving the nose down. It’s not horrible, And I feel I still have decent performance. But it definitely feels like the power is hunting for a direction to go.
This is just friggin ElkSh3Y. You built a wedge, that is great for plowing snow. You don't want to plow, you want to ride free on top of everything. Wedge hulls plow mud down here and I am sure they treat snow the same. You want a big pad up front to react the thrust moment and lay down the grass, snow, mud, whatever. The rest will follow just fine.

As for #4, you are building what I have considered, just eliminate the stoner in the driver's seat and run it remotely. That damn thing would beat me to death in an hour where I run, but 4 drone airboats could be really useful for me, a dog I can steer. :scratch:
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

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Re: Runners on hull?

Post by SuprchgedPalmBeach » Tue Nov 20, 2018 10:48 am

Just looking at the pictures it looks like it would definatly run on its nose. the majority of your weight needs to be on the heel of the boat.
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Re: Runners on hull?

Post by bkmail » Fri Aug 09, 2019 1:18 am

You ever get this worked out?
I remember you were planning to moose hunt the sloughs around Fbx with it.
Im curious if you have an upcoming hint planned as season opens rather soon.
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Re: Runners on hull?

Post by bkmail » Mon Jan 13, 2020 11:50 pm

Image


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Re: Runners on hull?

Post by kwanjangnihm » Tue Jan 14, 2020 4:34 am

" I don't care who you are back in the world, you give away our position one more time, I'll bleed ya, real quiet. Leave ya here. Got that? "

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Runners on hull?

Post by bkmail » Tue Jan 14, 2020 2:25 pm

Thats the same ad I just posted.....?!

Guess the “experiment” mini didnt work out so good.


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Re: Runners on hull?

Post by kwanjangnihm » Tue Jan 14, 2020 2:47 pm

BK I just added the link to the ad in case someone wanted to check it out.

Looks like a different design from the first unit.
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Re: Runners on hull?

Post by bkmail » Tue Jan 14, 2020 3:34 pm

Agree, or he modified it a bit.
Either way......
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