The best assurance that you can gain is: Stay off boats!.. Like anything else you can ensure that common sense is the most predominant factor. You are in more danger in a car than a boat, as long as the skipper knows his stuff. Wearing life jackets, having on board survival tools like: flares, locator unit, fire extinguisher, food & water, maps etc are as important as your ability to enjoy boating without worrying about safety as the expense of your enjoyment. Come fishing with us.. We chase Marco Sharks (they often jump into your boat when hooked)
I will be assured of my safety if the boat didn't move. As it so happens, a few years ago I spent Christmas on a Yacht converted into a hotel. (Sunborn Yacht, London) Doesn't move but stays afloat. Antytime, your in London, consider staying there.
Only life jacket can help you a little when you are on a boat that sinking or is in troubles.Even you were the jacket you dont know how long you stay in the water.After a few hours maybe you have hypothermia which is very serious.If you are to the ocean some fishes like sharks are very dangerous.I suggest to stay close to the boat but not in his sinking whirlpool that can take you to the deep.Anyway is very very difficults no matter how good you can swim.AND DONT BE BASED ON MOVIES.Never a boat is 100% safe.
1. Discover and plug leaks before launching a boat in water. 2. Wear a life vest. 3. Stay away from malicious boaters. 4. Understand that weather is either your ally or your enemy. 5. Don't forget sunblock.
Probably a list of 100 or more things here, but these are my basics.