No, it'll pack to the side
I was also advised in my Power Squadron course, to just pick it up and shake it occasionally, just to make sure the 'stuff' in it hasn't settled, or even solidified.
My .02
Boat shaking it causes it to settle but people shaking it causes it to unsettle? I don't get it?
How about the iboats store:
http://www.iboats.com/Plastic-Brake...4197486--**********.500868610--view_id.188030
From the title I'm not sure if this is an extinguisher or just the bracket.