Boat rental release of Liability MICHIGAN

I have customers asking to rent boats. I have a canoe, flat bottom and small fishing with only an electric trolling motor. Do I need specific insurance for this or will a release of liability take care of any possible drownings etc., and cover me. Part of my release states does hereby release, cancel, forgive and forever discharge ____, from all actions, claims, demands, damages, obligations, liabilities, controversies and executions, of any kind or nature whatsoever, whether known or unknown, whether suspected or not, which have arisen, or may have arisen, or shall arise by reason of the incident described above does specifically waive any claim or right to assert any cause of action or alleged case of action or claim or demand which has, through oversight or error intentionally or unintentionally or through a mutual mistake, been omitted from this Release.
I live and do business in MICHIGAN

[msgny]

The release certainly helps but is not 100% effective; some insurance is advisable.