You don't want to use a climbing harness for a safety harness on a sailboat. A climbing harness fastens around your lower torso, and if you fell overboard, would drag you face down in the water and drown you very quickly. A sailing harness is designed to attach a bit above your center of gravity, so that you will get dragged head up, and hopefully not drown in the process. .
It was a vague supposition based on the superficial resemblance. I have some old but massive Lirikis harnesses, plus an integral harness in my SOSpender auto/manual, but ideally I'd like a harness alone, plus a "floater" vest. This is possibly the best combo for sailing alone or when on night watch, because it doesn't require you to be conscious should you somehow fail to hook on and get washed over, and there's nothing to go mechanically wrong.
I tend to wear floatation vests in the Zodiac for the same reasons...if I get knocked out, I need to float head up and I can't expect my six-year-old to haul me in. Maybe to lash me on...
When there are other crew on deck or at least aware of me moving about the boat, I prefer the "deflated collar" types, because they are cooler and less confining.
One point for those intending to crew: you can't take the cylinders on planes and buying replacements overseas is not always possible.