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raft with pvc floats?

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Unread postAuthor: ammosmoke » Sun May 13, 2007 2:21 pm

Yeah, I meant hose clamps. I am pretty sure that putting spray foam in there would make it float better, and it would also eliminate the risk of leaks! :D
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Unread postAuthor: frankrede » Sun May 13, 2007 4:44 pm

I don't know if it would help it float, because foam isn't lighter than air.
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Unread postAuthor: squeaks » Sun May 13, 2007 6:45 pm

Okay, now that you people have argued for four pages, let me settle this problem here. Buoyancy is based on the mass of the object and how much fluid it displaces. Therefor, pressurizing will not make it float better. Neither will filling them with foam. Pulling a vaccum won't really help because it eliminates a negligable amount of mass. Lastly, a pressure relief valve isn't necessary because the heat will cause about the same amount of pressure as setting some tupperware outside with the lid on.

hooray for misunderstanding of physics principles.
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Unread postAuthor: c19o » Sun May 13, 2007 7:12 pm

If you bolted the pipe to the plywood it would be good to fill the pipe with foam so incase it does leak water cant get in because of the foam.
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Unread postAuthor: iknowmy3tables » Sun May 13, 2007 7:25 pm

that is true, I think if you put schrader valves on it you could easily repair leaks with that tire repair aerosol stuff, you might want to consider plugs for draining so maybe some loose rubber schraders with partial caps and washers so they don't fall in
cell core abs will be fine
you can use hose clamps to attach the floor which can consist of plywood you could probely have a small pvc air tank for watter cannon, propulsion, etc
you could hold the chambers together with reducing tees
for cheaper caps and streamline you can sand 3" caps for streamline shape
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Unread postAuthor: squeaks » Sun May 13, 2007 8:05 pm

definately go completly DWV. Holy crap! I can't believe I just said that. Whatever, yes, DWV. It's a lot cheaper. as he was saying, you could use t's and crosses to connect them together. Or you could just lash them together like any good boy scout. Just go to wikipedia, look up the formula for buoyancy, then use that to calculate how many floats you need for your given weight.
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Unread postAuthor: frankrede » Sun May 13, 2007 8:27 pm

USE DWV NOT BECAUSE OF PRICE, BUT BECAUSE ITS LIGHTWEIGHT
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Unread postAuthor: turbohacker » Sun May 13, 2007 8:30 pm

Thank you!!
Pressure will have nothing to do with the floatation!!
The only thing adding 50 PSI to the pipe will do is add weight, very little weight, About .102 lbs per square foot per 15 psi
theirfore you should not pressurize it at al!! :blah5:
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Unread postAuthor: pyrogeek » Sun May 13, 2007 8:48 pm

If you already have the tanks, you may as well just spend the extra money and make them out of Schedule 40. That way you could power a water gun, cannon to fire a rope to pull you to shoar, whatever.
That will be more expensive, and will require larger tanks to offset the added weight of materials and such, but it would be cooler.
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Unread postAuthor: to_live » Mon May 14, 2007 6:50 am

use styrofoam aswell incredibly light and floats really well, my cousin used just that to make a whole bloody boat
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Unread postAuthor: goathunter » Mon May 14, 2007 8:15 am

Why not use plastic 55 gal. drums? Ask at your local car wash,they'll give them to you for free.
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Unread postAuthor: jimmy101 » Mon May 14, 2007 10:27 am

You don't need a relief valve. PVC (even cell core) will handle the very modest pressure rise you might get.

If you glued the pipes closed on a very cold day (30F, -1C) then set them out in the sun on a hot day the pipes might heat up to 150F (66C). The pressure in the pipes would be about;
Code: Select all
    (66+273)/(-1+273)*14.7 = 18 PSIA (~3 PSIG)

So, there would only be about a 3 PSI rise in the pressure. Heck, a plastic milk jug will handle 3 PSIG without any problems.

-------------

It is pretty easy to calculate what the volume of the floats need to be to support a given weight. The density of water is 62 pounds/ft<sup>3</sup>. (1 ft<sup>3</sup> = 7.48 gallons, 1 gallon of water weighs 8.3 pounds.) To support 300 pounds gross weight (weight of load plus the PVC, decking etc) you need to displace ~5ft<sup>3</sup> (~38 gallons) of water. Of course, you'll want to increase the total float volume by a fair amount (perhaps 20 or 30%) so the deck isn't awash.
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Unread postAuthor: iknowmy3tables » Mon May 14, 2007 2:43 pm

make a seperate tank if you want to power water guns and stuff you can use dwv fittings but not pipe on cheap water gun tanks

wow i just had a freaky idea of making a man powered submarine from pvc :lol:
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Unread postAuthor: Orpackrat » Mon May 14, 2007 2:47 pm

iknowmy3tables wrote:wow i just had a freaky idea of making a man powered submarine from pvc :lol:


Dry, Semi-dry, or wet?
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Unread postAuthor: iknowmy3tables » Mon May 14, 2007 3:16 pm

wet of course its just a silly Idea I can up with when thinking about this
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