underwater physics help

[kat]

pulling my hair out, and hoping someone has some knowledge or inspiration. we need to move some barrels from under the house (floating home) they are plastic 55 gallon drums filled with air, bungs pointing down. none of us are superman, so physically rotating is not an option, and therein lies the physics challenge. a barrel full of air has 450lbs of lift. i do want to use the barrels again. any thoughts?

[Nwbrewer]

pulling my hair out, and hoping someone has some knowledge or inspiration. we need to move some barrels from under the house (floating home) they are plastic 55 gallon drums filled with air, bungs pointing down. none of us are superman, so physically rotating is not an option, and therein lies the physics challenge. a barrel full of air has 450lbs of lift. i do want to use the barrels again. any thoughts?

Remove bung. Pump water in until neutral. Move as desired, pump air in, replace bung.

[Mattleycrue76]

I might be imagining this the wrong way but if the bungs are pointed down you won't be able to pump any water in unless you find a way to vent air out of it since the air would only compress a little.

[kat]

therein lies the problem. we have fashioned a venturi, but i think it will be painfully slow. hoping for something more feasible.

[Mattleycrue76]

How about a hose and an airpump? You could suck the air out of the barrel causing it to flood.

[Mattleycrue76]

Or use some large diameter hose for you venturi and attach some weight to the barrel. That ought to speed things up

[loanwolf]

Usually barrels have 2 bungs, a large on for filling and emptying and a small one for venting. If the large one is down the small one should be up and allow for venting to get water in.

Are you looking at putting something new under the home to replace the barrels? Or do you just need to move them to a better location under it?

[airsix]

1) Use a hose smaller than the bung hole so water can flow in around it.
2) Since you apparently can't rotate the barrel so the bung is up you'll have to suck air out instead of pump water in.
3) Stick the hose up high into the barrel and pump the air out (a shop vac would work). Water will flow in from below to replace the air being drawn out.

With the bung at the bottom, pumping water in will just result in it being purged back out the bottom since the air will remain in the pocket above the hole.

(When I went to post I see that Matt pretty much has the same idea.)

[kat]

the venturi is 1/2" tubing, and is already built. an electric pump underwater might be a little problematic, and there is a bit of distance between topside and barrel placement, a bit too much i think to overcome head pressure. i would estimate 5-10 feet down, and about 15 feet over on average.

both bungs are down in most cases, they were intended as a permanent application(you know how that goes...) we need to move them more outboard, we have too many in the center and our house is flexing unhappily. flat would be better.

[Sockmonkey]

A cheap and easy pump solution is one of these electric drill pump thingies. You just need one hose to plop in the water and another to run to your barrel.

Maybe you need some TP for your bunghole?

-Eric

(edited to add link to pump)

[blt2go]

OK, since you mentioned that the barrels are a bit of a distance away from the topside access, we need a longer range solution. My first thought was, as mentioned here, to simply pump water into the open bunghole, which would push the air out around the hose. You wouldn't need much pressure since you are only trying to displace water from close to the surface, volume is the key. You could simply use a garden hose for your water supply. My one concern about that is that if the bung is on the bottom of the barrel, the water would simply run out the bung while compressing the air into the upper part of the barrel so they water would flow out just as fast as you try to fill it.

My next suggestion would be to use that garden hose and duct tape it to a shop vaccuum and suck the air out of the barrel and let water flow in the bung around the hose. Using a shop vac would be good since getting some water into the hose wouldn't be hazardous plus you could swap the hoses around on most shop vacs to provide for a little bit of low pressure air to adjust the bouyancy of the empty barrells.

Re-using the barrels might require a bit more planning and engineering since it might be harder to refill the barrels underwater and they are VERY difficult to handle underwater when full of air. Don't forget they are pretty close to weightless when they are waterfilled and underwater...

[loanwolf]

I am willing to come and take a look at this for you PM me. I have experiance with floating homes and docks.

[nice-diver]

buy new extra barrels for the perimeter and leave the existing barrels where they are?????????? why move around when you can just add more

[kat]

we have too much positive lift in the middle, and the house is bowing. we were able to get a couple of them out, the bungs were placed in a useful place, just hoping for a bit more flat...

[pogiguy05]

I was just thinking the same thing instead of struggling with moving barrels, just place more barrels where you need them and fill with air until they provide some lift. Then draw air out of the ones that are lifting to much until balance is as level as you would like it.

I am assuming that you can plug the bung hole so that it is sealed.Just a matter of moving air and not barrels.