The Jones Act is a US federal statute that applies to US flag vessels. It provides a means for crew members, who are injured as a result of negligence, to recover for damages caused by injury. It is the maritime version of workers compensation. If you employ any crew, then you should have an endorsement added to your policy to protect you from possible liability. When your vessel is disabled and you require assistance to return to safe harbor, then the Commercial Towing portion of the policy provides the coverage.
Most policies do include towing.
Some policies will include a dinghy and outboard motor at no additional cost. Others require an endorsement which schedules the additional equipment. Dinghies and outboards are insured on an Actual Cash Value basis.