Hi, when I was a decade or so younger, in better shape and more prone to risk taking, I crewed on several offshore racing sail boats. We usually raced without regard for the weather and when it was nasty we often took alot of water over the deck and experienced broaching and an occasional knockdown. In those conditions, I wore a Likaris harness with tether. There was 3-4 times that I ended up overboard. Only once was I fully in the water and being dragged by the boat.
I tell you this to share my observations
First, I could not believe the force of the water when being dragged behind a boat going 6 knots, it was alarming! The strap snapped taught and the bow wave from my face disoriented me. I could not pull myself back up the tether to the boat, despite my fairly good physical condition at the time.
Second, I could not get back on the boat under my own power on other occasions when I only went partially overboard. That is, I was hanging by the tether and one hand on the lifelines along the side of the hull. In my case I had the fortune of 2-3 strong guys to "yank" back on board.
Thirdly, I found my self physically exhausted in these situations as one expends a huge amount of effort as you instinctfully try to stay on the boat as you are in the process of going over. It is not always a clean "plink" into the water. So, you are in a very bad situation and already drained of you're strength.
Lastly, another factor to consider is you're state of mind. It is a situation where you're options become suddenly few. And you need to think clearly. We always had two hooks on our tethers so we could unclip if we had to, by only pulling back 2-3 inchs instead of cutting with a knife. Of course we were always reasonably confident that the skipper would come back and get us... Single handing is a different story. I would recommend an inflatable life jacket with light and mirror so if you find yourself with the need to make the grim decision to let the boat go instead of drowning you have a better chance of surviving. I would also recommend a short tether to keep you on the boat no matter what. Unclipping and reclipping is a reasonable tradeoff.
Today when I single hand my power boat I wear an inflatable with integral harness when I transit from the lower helm to the flybridge when running at speed. I us a short tether as I definatly don't want to be dragged by that 200hp Volvo diesel running at 3/4 speed. If I have to go forward when alone, I slow down the boat and clip and unclip.
Just some things to consider, I hope you find them usefull.
Tony
tony.raymond@worldnet.att.net