Mich. Comp. Laws § 255.5

Sec. 5. Every person applying for such license shall, before the same be granted, give bond to the people of this state in such penal sum as the said board shall direct, not less than 200 dollars, with so many, and such sufficient sureties as the said board shall direct and approve, upon condition that he will faithfully keep and attend such ferry, with such and so many safe and convenient boats, and so many men to work the same, together with sufficient implements therefor, during the several hours in each day, and at such several rates, as the said board shall from time to time order and direct, which bond shall be filed with the county clerk.