Great Orange Navel Race

Now you're cooking. Fans aren't the best way to propel a boat, in fact they are pretty inefficient and very slow to cause the boat to respond to steering input changes (they skid sideways pretty badly). Props in the water is a better answer. A pontoon boat is simple enough, though requires the effort of building two hulls the same.

Personally, I'd build one hull. I'd have a relatively long beam to length ratio to permit easy propulsion and use the orange for stability. Think long and lean, with the orange low in the hull, but not so much so that it requires you shape the hull around it, causing additional displacement and drag. Steering with duel props is a fair idea and a faster response then rudders.

You may want to look at skiffs, sharpies, canoes and other high beam to length ratio craft for hull shape ideas. Keep it simple (the hull shape) as I don't think your speeds will warrant working out a full plane shape. A flat bottomed, thin skiff will plane if enough power is available.

Foam is a good material to carve your hull from, though some types of foams will absorb water, making them considerably heavier, pretty quickly, which wouldn't be good. Do some tests or find some "closed cell" foam to get a material that doesn't suck up a bunch of weight. I wouldn't worry about how smooth the exterior surface is, though the smoother the better, your gains will not be particularly significant.

Your props can just dangle off the end of the boat. They don't have to be buried inside and come through the hull bottom. Keep the shaft angle as close to level as you can, you'll get more thrust efficiency this way.

I'll let you work out the timing issues, which should be easy enough over a fixed distance course, once you have a handle on the speed you'll get from you boat.

Stream lining is more shape then surface prep. If you have a reasonably smooth surface, then your hull shape and power on tap will govern it's speed.

Personally, I'd be working with hydrofoils and a cantilevered prop shaft, but I'm a touch odd. Where's Doug Lord when you need him . . .

 

Well I was thinking about using a fan motor to power the prop since i can probably get two fan motors that have setting for high medium and low. I was thinking that during the straight away the both obvious be on high so I could gain speed. Then when the boat goes into the turn turn the left motor on medium or low maybe even completely off so that the boat would be able to turn on a dime. Then somehow have the motor turn back on so that the boat can straighten out. i agree with you about the hull shape. I have been tossing around ideas and even though the pontoon boat seemed easy to build, I dont believe that I would have the kind of turning radius that I am looking for. Another aspect about the pontoon idea that i did not like was that I dont think that I will be able to get it up to a fast speed. If you don't believe that the fan motors will not work can you suggest some kind of cheap motor to use in exchange that would have enough power to turn the props

 

Fan motors will turn your props, maybe a flexible shaft too. It only has to survive a few hours, much less in actual operation so don't worry about the thing burning up. Some simple experiments with prop diameter and pitch will yield a pretty good propulsion unit(s). I'd go with a two blade prop for ease of building. Make up a few different ones and see which works best on your little container vessel. Don't worry about gear reduction or any of that, just a direct drive shaft with a prop attached to the tail end of it.

Think light weight. Small DC motors are available at Radio Shack or better yet SkyCraft in Orlando (the place with the flying saucer on the roof). In fact, you'll probably be able to find everything at SkyCraft and pretty cheap too.

You can actually get some real small props from the RC guys, try hobbies in the yellow pages (Hobby Shack, in Orlando, I think). These will kick some butt with a high revving motor.

Since you'll have a motor or two, you can easily V belt off the shafts to drive a timer or two, though a little thinking would produce some timed switching.

 

Ok I found DC motors but do have any recommendation which type of motor to use. There are various motors available from Radio Shack. I found a 9-18VDC motor available for like six dollars each, which is easily in my spending limit with alot of money to spare. I am looking for timers and switches so that I am able to turn off the motors and turn them back on. Any ideas? Ive looked on various sights already but Ive never done anything like this so its all new to me. Ive never worked with circuits before so i have not clue where to start. Any way you can do some coaching to help me understand what is needed to do to create these switches and timers so that I am able to shut down a motor and turn it back on so that I can be able to turn the boat.

 

I would think your 9V motors could be controlled with a simple flashing light circuit ( available at radio shack ) with a pot to time out the freq of when the motor is on and when off.

K9

 

You have a motor that is running. If you have this, you have potential for a timer and no need for additional electrics. A small shaft, with a belt on it, turning a substantially larger free spinning wheel can offer a world of options (geared way down to suit your steering needs). The wheel could be a cam or have an actuating pin sticking up though it to make contact with something (like a switch). The whole point working out these issues, doing some testing, then some model development, with an eventual entrant into the race, that incorporates what you've learned and figured out. Other then the motor and batteries, you could do everything else mechanically.

 

Great application for an old-fashioned sidewheeler design! For authenticity, it would have to explode at the end of the race.

Sounds like the biggest trick is navigating the course. Will you be able to make test runs? What will the course be marked with? Going straight up the middle, of course, will give you a faster time than bumping around the outside edge.

Too bad the teammate is required to pick the orange up off the boat. If you could catapault that sucker about eight feet from the finish line, you'd shave off maybe half a minute.

 

"Great application for an old-fashioned sidewheeler design! For authenticity, it would have to explode at the end of the race."

Too funny.

 

The hard part will be the steering system. While a finger or similar to scrape the side of the pond might steer..

It is probable that the land will be warmer than the water.

Could a cheap enough heat sensor be wired to keep away gently from the warmer shore?

FF

 

How many revolutions of the motor's shaft will it take to travel before you need to start your turn? Can a gentle turn (fixed rudder deflection or natural prop walk) be used to get around the semicircle fountain?

 

Any kind of rudder or prop walk would work it just all depends on preferences. Any suggestion which on would possibly work better?

 

When experimenting on something as odd as this, little evidence exists, so you're left to simple tests and educated guess work. The rudder would work better at higher speeds then prop walk, but lower speeds prop walk would be more beneficial.

 

i have no formal education in boat building.....


however....as as far as navigation goes......we can only guess at the design of the course......at this point it seems circluar...scrapping the edge will not work....too many variables....the intermittent motor will work...but how you gonna time it?...gotta be bang on and reliable......id go rudder.....
but you cant fix position it.....

a person could hook up a clock....every time the hand came around...it hits the rudder....after contact...the rudder straightens out via elastic bands...and the craft goes straight again......

the amount of times you turn are calculated by the amount of times the rudder is moved...this is adjustable.......

i would also think a dc 9 volt motor would spin just great for this.....

as far as constructing a hull........get a toy boat......use it as a mould...and fiberglass the thing....release the mould....and...bada bing.....a hull like you want...light strong...you could make several...to test...supplies would be begged from scraps at a fiberglass shop....

just some ideas for you to choose from

 

If the pond is circular, with a central fountain how about something like "control lines" like on early model aeroplanes held in a circular pattern by 2 equal length "piano wires" and lots of - other way rudder to keep the wires tight. then lots of speed... Quickly re-link wires by paper-clips and re position rudder for equally speedy return trip.... (paper-clips are cheap - only $10 each at Pentagon - old stock I recall)

 

If you read the posts folks you'd see the fountain is semi circular and that "wires" or other attachments aren't permitted to control any element of the craft.

Timing is an easy thing when you have a battery or motor on board.



It liked doing "U" turns and doesn't appear to have any directional control options. It's rudders show some deflection, likely to counter prop torque. Apparently about a half a dozen actually completed the course last year.