

The entire process of developing Project rRaft was documented at rRaft.blogspot.com.


Step 1: How Many Bottles?


Section 1


  • The average water bottle contains .5 Liters of water.

Archimedes' principle, or the law of upthrust says:




Section 2


Easy as that!
<p>Can I use pool noodles?</p>
what are other alternative for material? we are going to use it for our investigatory project.:)<br>and also can we use it in flash floods??thanks!:))
using it in flash floods actually sounds like a goog idea
It's Florida...the leaves don't fall and the water doesn't freeze. That doesn't mean anything less than a polar bear could bare that water.<br/><br/><sub>(get it, bear-bare? hehe)</sub><br/>
hey i liv in florida too! how old r u?
Haha. I will admit, that made me laugh.
when you&acute;re counting bottles don&acute;t forget to take into account the weight of the deck material.
Can I do this with Arizona tea jugs?
Sure, you'll just have to do the buoyancy conversions yourself.
do you know how much weight&nbsp;a 2 liter soda bottle would hold up? i want to make somthing like this and it might be faster to get soda bottles instead of water.
My guesstimate, without doing any real calculations, is about 4 lbs. per bottle. An empty bottle will hold up about the same weight as the weight of the amount of water it will hold, plus or minus a little bit, depending on how heavy the material of the bottle is (minus for materials heavier than water, like glass, plus for materials lighter than water--I'm guessing a lot of plastics are lighter than water, but I don't know for sure (fill a bottle, leave the lid off, and submerge it, see if it floats or sinks).<br> <br> Also, if the bottle collapses slightly in water due to the weight of the water pressing against the outside, there will be a little less volume and thus it will support a little less weight.<br> <br> A liter is a little bigger than a quart, a gallon of water weighs about 8 lbs, so a quart weighs about 2 lbs, so guesstimating that 2 liters will support about 4 lbs won't be too far off.<br> <br> You could also simply fill the 2 liter container with water and weigh it--like I said, it will support about the weight of water it contains. (If you want to be precise, you could subtract the weight of the air the bottle will hold when we call it empty, but that is negligible. You will have to account for the slight collapse of the bottle underwater (as mentioned above), so if you weigh the bottle full, figure it will support a little less than what you weigh.<br> <br> Of course, you'd want to figure on using more bottles than this caculation indicates, to account for all kinds of things, including the potential of bottles springing leaks due to collisions, abrasion, or whatever.<br> <br> Hope this helps!
You're welcome!
<p>You can get a lot of bottles at small businesses that you&acute;re familiar with, like restaurants. Once I went to a small casino to get bottles (not familiar with) and got like four BIG and FULL black bags of 2l bottles.</p>
How many bottles would you guess be needed to support around 120lbs.?<br />
&nbsp;121, plus the weight of the raft. But thats to be neutral, you need extra buoyancy.
Cool. Thanks.<br />
Hey Weissensteinburg, thanks for&nbsp;replying&nbsp;to&nbsp;several of my comments from a while ago. Because of that, I started to collect some water bottles, now I think I have enough to hold me above the water. I'm gonna be&nbsp;building&nbsp;a kayak for this one race that is going to be held this Sunday. Hope I can build it before Saturday and test it before the race. Thanks for all help from before.
No way! You'd need about thirty .5 liter bottles. The average plastic water bottle is .5 liters. If you want the exact amount, it's easier to work in kilograms. One liter of air will support one kilogram of weight in water. <br/><br/>30 lbs = 13.6 Kg<br/><br/>So to support 13.6 Kg, you'd need 13.6 Liters of air. That's 27.2 average water bottles. Remember you also have to account for the weight of the plastic and that the 27.2 number is only to equalize the weight. You'll want to use extra if you really want it to act like a boat.<br/>
About 2.2 lbs equal one kilo
the picture blocks the third step D:
whenever it does that just refresh the page
What do you mean?
Could i use those 5 Gallon Bottles that are used for water Like the ones in the Picture,I ended up with about 20 of them.
It doesn't look too cold where you are... Shorts and a T-shirt! *envy*
No, the air temp wasn't too bad (florida) but the water is ridiculous!
For the record, it was 22 degrees a couple nights before.
Over here in Canada, it's -43... AIR TEMPERATURE. The water's frozen by the way... AND NOT ALL OF CANADA IS LIKE THIS(for thick-headed people) I LIVE UP NORTH>>>
your lucky i live in a cave in the middle of the saharan desert, the only way i get communication is by the seldom passerby with wifi
in the summer it gets to +40C in the Okanagan some days!
Dude. You are so right about this, not all of Canada is cold, i go up their for the summer and sometimes the winter and its not always effing freezing like people think. They're always like Canada!! In the summer, you must freeze when in reality its nicer, because isn't 75 nicer then 90, I think so! CANADIANS UNITE! yay.. BTW really cool instructable, I'm going to try this with 3 Liter pop bottles. :)

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