Generally waivers for anything are not worth the paper they are written on. Not only does the spoken word and a handshake mean absolutely squat today, the written word carries the same worthlessness. We are now a country without the rule-of-law after 200 year of priding ourselves on this virtue. This applies in both civil and criminal law.
You signed your post "Captain" that means you are at fault and will be sued by someone no matter what. If you are judged as not being responsible for a mishap which resulted in death or injury, you will have spent tens of thousands of dollars in lawyer fees and court costs defending yourself from every Tom, Dick and Harry who knew the injured or deceased.
I am a retired airline captain and once had the similar responsibilities as you, but I had a total indemnification for any of my actions in the cockpit from a multi-billion dollar corporation (my employer) and backup from one of the strongest labor unions in the country who would provide the best lawyers money can by.
An average citizen? Not much chance. If you have a paid crew find out what kind of insurance they have (and have them sign their death benefit over to you, just kidding). Boat insurance, check you personal liability. An umbrella policy, make sure it covers the operation of a boat as well as you car.
Good luck.