Behavior of floating structure

[Megaman8]

Hello All

My goal is to improve the floating stability of the following structure(attached JPG) my biggest problem is to calculate it's "center of rotation"
The structure is 90% submerged, It's floating center is higher the the mass center there for it is מaturally stable, now the question is should i consider it's C.M as the rotation axis?
or should i go and calculate its metacenter because it is not fully submerged.

Thanks all
Jenia.

 

[IRstuff]

Your file seems to have a pathological name and can't be downloaded.

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[BUGGAR]

Calculate the metacenter and do the usual stability calcs. Are you shooting for a specific metacentric height? I didn't open the file.

 

[Megaman8]

i have uploaded the picture

BUGGAR, the metacenter need to be found even if the body is netural stable (F.C higher then the C.M)?

 

[IRstuff]

Is what you're calling the "floating center" the center of buoyancy?

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[Megaman8]

Exactly

 

[IRstuff]

Why do you think it needs to be more stable? Your CM is pretty low already.

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[Megaman8]

The bottom horizontal part of the hollow structure must be parallel to the water line, sometime water can lack inside and till the structure.
I need to design the right size floats and it's distance from the center of the structure to overcome the weight of the licked water and maintain economical
solution

 

[IRstuff]

Why not just leave it open altogether and flood the inside of the hollow structure? Or backfill with foam. Wouldn't that alleviate this leakage problem?

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[Megaman8]

you are right, but in this case the structure must be hollow to ledd air to it's bottom part.
my only problem is to understand if the mass center or metacenter are the rotation point of the structure, the moment i will be able to find the rotation point is the moment i will be able to creat a free body diagram from this point it is simple mechanical engineering.

Do you think i need treat the metacenter as the rotation point of the hole system?