Re: Professional Liability Insurance for delivery or hiring crews
When I was making my living as a full time delivery captain, the vessel's insurance policy covered the vessel and crew. I would suggest that you not deliver an uninsured vessel; if they can't afford insurance, at least for the delivery, maybe they can't afford to pay you?
I had a contract that the owner or agent (bare boat company operations manager) had to sign. Simply put, I was responsible for any damage to the vessel on the voyage that was not covered in an "acts of God" clause such as running through crude oil at sea, a lightning strike or hitting something at night, etc. The contract made me a very popular delivery captain, even though I rarely had damage to pay for out of my pocket.
Keep in mind that most sailboats that you will deliver are not being delivered by their owners or captains because there are significant problems with the boat. For instance; one at the end of it's bareboat service. Do a quick visual survey of the boat upon boarding, noting on the contract any damage or problems, just like you do renting a car. Carry a very extensive tool kit, a sail sewing kit and lots of duct tape. (PM me if you'd like more detailed info, but be patient; internet here in FdF is terrible).
As for crew insurance, especially those sailing for experience (non-professionally), say on a cruising boat, again it should fall under the vessel's own policy, but there is an "element of risk" factor when choosing to undertake a crew position on a boat which an attorney told me laid most of the burden on the crew doing as directed by a competent officer. However, if some very stupid woman can put a cup of hot coffee between her legs and get rich by blaming someone else when SHE spills it, who knows?