Aw shucks...
must remain afloat....
was going to ask..
can it move 50 yards straight DOWN

 

Simple is usually better. However, if there are 30 entries and all are simple and basically the same you don't have much of a chance to win. Something more sophisticated that might only work 50% of the time, but works great when it does, will often give you a better chance of winning. Many professors also like to see students venture into new territory instead of just doing the same old thing. When you start looking for a job and need a reference from a teacher they will remember if you did something innovative or something bland.

If you build a flat bottom that is square it won't be very directionally stable. Using a multi-hull will make it want to go straight. You could build it so that the steel plate is in the middle (possibly even below the water line) with two outriggers to keep it upright. For that matter, who's to say there should be an upright or not? The boat won't care if it's capsized or not as long as it's afloat. Then you'd just have an issue with steering. The plate won't be very big. A 10lb steel plate 1" thick will be about 3"x12". IIRC, water weighs 8lbs/gallon, so three two liter bottles would float 10 lbs with some to spare. You can also get big chunks of styrofoam from Hobby Lobby and make your own pontoons that are closer to the maximum size. Mailing tubes can also be made into pontoons as long as they are waterproofed well.
Long skinny shapes move through the water more easily than fat shapes. Instead of going for a huge plate that only sits in 1.5" of water, you will have a more efficient shape if you use streamlined 4.5" pontoons that sit 3" in the water.

 

I would go with the two liter bottles, seal the tops of them to make sure there are no leaks, without a sure payload size and weight, it's hard to say what to do with that. It doesn't have to stop does it? I know I had a project with a car having to carry a payload 25 feet and stop dead on, didn't make it, had problems with wheel alignment and fell 4 feet shortthats what happens when a few ideas fail and you have a night to piece together something that works. Just keep it simple, don't go anything big and complicated, thats why our ideas failed with that car, the simple design usually succeeeds, less parts to fail. Good luck.

 

I just love thinking of ideas that are outside of the box. I enjoy engineering stuff like this.(I'm currently pursuing my AS and BS in ME.) I haven't used that software program. We used ProE Wildfire to design and build a wooden model bridge. Our team placed about 3rd or 4th for weight to strength ratio. It was a blast watching them test each bridge to it's structural limit and then splinter into pieces.

Here's my thoughts on your project:

>>>>>> The professor will probably grade you on how efficient and applicable to real world use your design could be. <<<<<<<<<<<<<<

*******The one question I would need answered is; is this a one way trip or is the boat supposed to take the payload out and return????********

so with that in mind here are my two ideas:

1) There is no replacement for displacement.(That usually holds true for engine power so I figure it applies to on the water cargo transport.) You've got the right idea with using the flat bottom boat style container. The smooth metal could provide for less drag than pop bottles or styrofoam surfaces. (A little coat of turtle wax couldn't hurt either. )For propulsion you could use a small compresssed air or CO2 tank. I would think that a single paintball gun tank might be too small to go the distance. If a larger CO2 tank(like for welding) is too big and heavy then I would go with multiple paintball gun tanks with air lines run in parallel. Regardless of the compressed gas source you will need to have it discharge through a small orifice to compress the gas as it exits, into the water, to increase propulsion. Getting the boat to start moving will take the longest. Once in motion the compressed gas should be more efficient. As for steering, you could go that route with the r/c parts, but that adds to cost and weight. I would be tempted to use a couple fishing poles with the monofilament tied to a rudder. If you had two poles then you could have two people seperated a distance so one could pull and steer right while the other would pull and steer left. Simple, cheap, probably not that pretty but in theory sounds good to me.

2)For option two, keep the flat bottom boat idea, but the propulsion would be provided by the weight of the payload. I would use an elevated tube and rubber bellow, standing up in the boat, to provide a resting platform for the payload. Have an air line run from the base of the elevated tube to an orifice in the back of the boat into the water. As soon as the payload weight is transferred to the platform it could compress the rubber bellow and thus force the air out of the orifice into the water and propel the boat. The trick would be to make the tube and bellow tall and wide enough to allow the contraption to make it through the whole distance. Again, for the steering, I would use a couple fishing poles as described above.

 

Where are you going to school? I'm in BA and have been thinking about going back to school.

 

Heya Silverstreak, I'm at TCC right now and will transfer over to OSU Tulsa. By the time I'm ready to do that they should have all the improvements and new buildings and landscaping done to the site. I can't wait. I'm sure they will have more classes available here in Tulsa too, so that means less busing to Stillwater for classes.

Back to this project; If you don't want to do the fishing pole steering setup, you can get one of those cheapy fully functioning R/C cars at wally world for under ten bucks. The range might be close to what you're lookin for. I also wanted to point out that the first design option that I gave should also work for the speed boat racing. The second design that uses the rubber below and payload weight propulsion wouldn't win any speed races, but if ya'll had a tug boat contest to see whom could get their boat to move the most weight on the water, I bet it would take the prize. Well, whatever ya'll come up with, you have got to post pics and results up here for us to look at and marvel at.

 

Okay, I'm curious. Did this project get started? If so, how did it go?

 

I've been wondering too; I was just too lazy to go dig up the post and resurrect it.