The workvest (Stearns) that I use has limited pockets. I carry a flasher hooked to one shoulder, a 55gal and 35gal garbage bags, signal whistle (tied to zipper pull tab), and a signal mirror. In my Radio Pouch are spare batteries and a flashlight.

When expecting Hurricane winds, we hand out a ziplock bag with 3 Granola bars and 3 nutria fruit bars, and 2 bottles of water. The emergency rations will fit into a pocket but the bottles of water are stored inside of a person's shirt.

The canals we sail through are not as deep as we are tall. If we sink in a canal, we just climb up to the flying bridge and wait for help. If we sink in the Mississippi or Ohio Rivers, we'll be swimming to the nearest bank, and will try to be as comfortable as possible while waiting for rescue.
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QMC, USCG (Ret)
The best luck is what you make yourself!