Does a signed waiver mean I don't need insurance?

No. A waiver shifts and reduces certain legal risk in a dispute, but it does not pay a claim -- insurance is the layer that actually covers a loss if something happens.

Do I need a separate policy for watercraft or motorized equipment?

Often yes. Many general liability policies exclude watercraft and certain motorized equipment by default, so check with your insurer whether you need a specific rider or separate policy for those categories.

Insurance Requirements for Equipment and Party Rental Businesses

What insurance a rental business actually needs -- general liability, inland marine/equipment coverage, and how waivers and insurance work together, not as substitutes for each other.