pic: 648 Cardboard Crab Steer Boat 1

[SgtMillhouse648]

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[Jeremiah Johnson]

Here it is... I'm extremely excited about this innovative design. I'm sure it will impress a lot of people, especially the FIRST community.

Okay, so any comments or suggestions?

I think this may impress us on the speed also, the boat should be fairly lightweight and with the addition of a second propellor we should be able to turn some water. Unfortunately, I won't be there to oversee anymore of the build, I have work... lol.

[AdamHeard]

how do you know if it is buoyant enough?

[SgtMillhouse648]

Originally Posted by AdamHeard

how do you know if it is buoyant enough?

From experience on previous years' boats, we've had more of a problem with the boats being "too" bouyant. Last year's boat only sat in the water a couple of inches. Cardboard is surprisingly buoyant. The tetra pontoons will be plenty buoyant. By the way, does anyone know if and how you can set custom densities in Inventor? If anyone knows, I'll post the estimated weight of the boat.
Malhon

[AdamHeard]

I know you can set cusom masses by just filling in the box, haven't tried it with densities however.

[cire]

Very innovative! I like - I hope it works. Be sure to post pictures and videos of the real thing.

[dtengineering]

Originally Posted by Budda648

I think this may impress us on the speed also....

While I'm not familiar with what speed is required to make for an impressive speed for a cardboard boat, this design looks like it will experience a fair bit of drag compared to a more streamlined, single hull vessel.

You may also find that while this design will exhibit omni-directional drive ability, that it may also exhibit very little directional stability... the ability to track in a straight line.

It is a cool looking design, but I wouldn't expect it to go fast, or in a particularly straight line. Perhaps if the tetrahedrons were replaced with streamlined "rudders" that each rotated as the pilot did....

Jason

[Tom Line]

You will have a very difficult time steering this boat. If you're ever rowed a flat-bottomed inflateable dinghy in the wind, you'll know why.

It's a bit like trying to walk on ice.

Powerboats use a V shape hull for tracking, and sailboats use a keel.

You have a couple options to correct that. You can move the propellers so that they will pull the boat. Pushing an unstable boat is like trying to balance a shovel on your hand.

Or you can change from the tetra design to hulls that have self-tracking, like a catamaran.

A number of solutions - but you're going to have trouble if you don't implement one of them.

[StevenB]

By the way, does anyone know if and how you can set custom densities in Inventor? If anyone knows, I'll post the estimated weight of the boat.

Create a new material using the Styles Editor:
-Select "Default", or whatever is closest to cardboard.
-Click "New", and type in a name for the new material ("Cardboard").
-Enter the mass properties and click Save.
-You can also edit which texture the material uses by default, as well as other physical properties.
-You'll have to import the Cardboard material into each part. I'm not sure how to do this with Inventor 11.
-Set the part(s) to be cardboard.
Hope this helps!

[Jeremiah Johnson]

Originally Posted by dtengineering

While I'm not familiar with what speed is required to make for an impressive speed for a cardboard boat, this design looks like it will experience a fair bit of drag compared to a more streamlined, single hull vessel.

You may also find that while this design will exhibit omni-directional drive ability, that it may also exhibit very little directional stability... the ability to track in a straight line.

It is a cool looking design, but I wouldn't expect it to go fast, or in a particularly straight line. Perhaps if the tetrahedrons were replaced with streamlined "rudders" that each rotated as the pilot did....

Jason

Heh, the "impressive speed" is well below the speed required to win a race. We have some difficulties in the past about maneuvering the left hand corners of the 200m course. Our biggest rival is mother nature... if it's windy, we might be in trouble, but if it isn't, my guess is that we'll be fine and we'll be able to control the boat fairly well.

There is one thing that is for certain. When we go to turn and are carrying some speed, we'll somewhat drift around the turn. Carrying both forward and left motions. We'll also lose nearly all of that speed in the turn.

[EricH]

One thing--when you turn the pilot, aren't you worried about turning the boat instead? It would be easy to do--and just like a helicopter without a second rotor.

[SgtMillhouse648]

Originally Posted by EricH

One thing--when you turn the pilot, aren't you worried about turning the boat instead? It would be easy to do--and just like a helicopter without a second rotor.

That was one of our concerns, but we came to the conclusion that if the pilot stops pedalling at the turn, the resistance required to turn the pilot will be less than that required to turn the boat, so we shouldn't have a problem with it.
Malhon

[Jeremiah Johnson]

Originally Posted by EricH

One thing--when you turn the pilot, aren't you worried about turning the boat instead? It would be easy to do--and just like a helicopter without a second rotor.

If that happens, then I think I've got a fairly easy fix.

[Gertlex]

Tsk Tsk. I don't see a lifejacket there.

Interesting concept... certainly doesn't seem useful outside of still water (I believe that was already mentioned of course).

[SgtMillhouse648]

Well, we tried it yesterday, and won third place in our division.... It was extremely slow, completing the course in 10 min 50 sec (just as I was ready to pass out!!) , but it took on no water and didn't even think about sinking, even with one of the biggest kids on our team Tyler driving it. I think at Galesburg it will be for display purposes only... It turned on a dime as usual, but was slow. Our "FIRST" Attempt boat from two years ago took first place again for i think the fourth time. All in all it was a very fun competition.