You have a 50-50 chance to swim 50 yards in water at 50 degrees. Another rule is that a 50 year old person has a 50-50 chance of surviving 50 minutes in 50 degree water. Watch for initial signs of hypothermia such as goose bumps and shivering. Shivering may slow down or stop as hypothermia increases. Speech becomes slurred and incoherent, you become lethargic and uncoordinated.
Respiration becomes shallow and erratic.
There are rules of the water just like there are rules of the road. The Skipper is responsible for the boat and the passengers safety, as well as damage to other boats and facilities. You can sign up for classes through the US Coast Guard Auxiliary Home Page or the US Power Squadrons . They have courses all over the country. The courses are taught with learning in mind, by experienced people.