Bouyancy Calcs

[mbherlihy]

i am trying to figure out if I need a buoyancy pad for a residential pond outlet control structure (OCS - common term here in Georgia). Does anyone have a spreadsheet or a good reference to relearn how to compute and check for bouyancy? I want to make sure if I specify a concrete bouyancy pad, that it is the proper dimensions. I don't want my OCS to potentially tip over. This has happened in the past, with some of our heavyier storms.

Thanks.

 

[RWF7437]

Calculate the density of the empty OCS. If it is less than 62.4 lb/cu ft, it can float so you would need to add weight to it. If it is denser, you probably don't.

good luck

 

[chicopee]

also allow 2' draft so as not to take on water on windy days. we do that with cranes mounted on barges.

 

[mbherlihy]

Chicopee.... please explain a 2' draft. I'm not sure how to account for this or exactly what this means... thanks.

 

[chicopee]

I meant 2' free board-my apology.

 

[jartgo]

In addition to what the others have said, don't forget to subtract the unit weight of water from your counter weight materials (likely concrete). That is, the effective counterweight is about 85 #/c.f. for concrete (not 150#), because the bouyancy is acting on the volume that the concrete displaces also.

 

[civilperson]

If the pipe has an open end, no need to worry about buoyancy!