Tethered power supply brainstorm

As briefly as possible… My goal is to have a UAV on my boat that is connected to a power tether and provides a bird’s eye view. Basically just fly straight up and follow the movement of the boat. Maybe 100-150 feet height max.

I’m aware of tethered systems out there and they range in the $20k to $50k price range… I don’t need this that badly lol.

Ideally, I would be able to use the boat’s alternator as the initial source of power, even if I have to upgrade to a higher output alternator.

My initial thoughts are some kind of converter to boost the 12-14V DC way up at the base and then convert it back at the drone itself. This is where I am stuck… Trying to get some help from people who have a bit more expertise in this area.