Yesterday I dropped my wedding ring off a dock.
I got back to the marina in San Rafael at 7 a.m., and indeed the tide was very low, only a few feet deep where I’d dropped my wedding ring. I forgot a towel or anything else to make me comfortable after my early morning swim, which made jumping into freezing San Francisco Bay, in the middle of winter, that much worse.
I dropped a fishing weight tied to some 1/8” Dacron to mark the spot. Without a weight and a line, I get disoriented underwater, and my search becomes be willy-nilly and inefficient.
My first bottom scans were with a dive light, looking very carefully for any telltale, ring-shaped entry marks in the mud. I saw nothing and began a very light combing through the mud with my fingertips. I found the ring in seconds and put it back on my finger right there, mud and all, underwater. A very happy man was floating in the murk, under a ramp to a dock, at 7 a.m. Success.
My young bride was quite cool about all this, but I was pretty convinced, and I convince her, that I'd recover the ring.
This wasn’t my first rodeo.
A few tips on the subject: Normally I would drop something heavier, like a dinghy anchor, which will hold me in place on the bottom, but my ring was so tiny it might have been displaced by the anchor. If the search area is bigger, in other words, you don’t know exactly where something is, it’s time to divide up the pie and use two weights. Your center weight will have a line which runs to the surface…maybe to a float or to your dinghy. Your second weight will be attached to the first by another line, say thirty feet long. All lines should be fat and visible, because they’re there to be seen underwater.
Keeping the line taught between the two weights, swim the length of the line scanning on both sides (with a dive light, if needed) then move the second weight three feet and scan the length of the line again. You end up marking the bottom into a big pie with about a sixty-foot diameter, and this pie get searched in a fairly thorough and systematic manner. This is how I found my solar panel on the bottom of Sydney Harbour, in about twenty feet of water, after a rainstorm, when it was particularly murky (visibility less than six inches) and polluted.
If you’re in the clear tropics, your search will be made very easy, but if you’re in murky water you’re a crime scene forensic underwater investigator, and you’ll have to get systematic about it. Random dives to bottom just don't ever amount to much, unless you're lucky.