Most have been, and still are made mainly from steel.
The first boats were most likely made out of wood.
Boat hulls are currently usually made of fiber glass. Fiber glass is the cheapest, most effective material. Boat hulls can also be made of wood, carbon fiber, and steel.
Most boat seats are made of cloth, vinyl or plastic. Since there are many different kinds of boats there are many different kinds of boat seats. Overton's has a website with additional information on boat seats.
To entertain people and make money, same as most movies.
Wind pushes in to the sail on a sail boat, the boat then moves.answer 2It pushes only when sailing with the wind directly behind. Most of the time the sail is just like a wing, the curve of the sail causes the wind to move faster across the front of the sail (Bernoulli says faster air, less pressure), slower air behind sail (more pressure) sail generates "lift" in a horizontal direction and moves the boat. Controlling the shape of the sail and its orientation to the wind controls the lift it generates.The keel counter balances the weight of the sails and rigging and the "lift" generated by the sails, it also keeps the boat from just skidding sideways across the water.
Most boat dealers would lift it with a forklift. If you had an engine crane you could pick it up with that, if you had a way to hook onto the motor so it wouldn't fall or get damaged. Mercury four-stroke weighs 250 lbs.
Most lift kits will work for any truck, as long as you don't have an unusually narrow chassis.
I am assuming this is a sail boat, ski boat (jet boat). If the boat is made by a manufacturer the the hull will be strong enough. If the boat was made privately, the hull would be laid with plywood, then fiberglassed as a sealant strengthener. If you have an outboard motor on the transom, this must be well supported by "bungs" (which are the two pads at the back of the trailer. Most of the weight should be on the center-line (keel of the boat) and the rest should also be supported by the rollers.
On the stern starboard side most time engraved in the transom. It is a 12 digit combination of letters and numbers that identify the manufacturer and date a boat was made in addition to a unique serial number for that boat.
Hydrogen, being the lightest element, would provide the most lift.
The most famous and successful car-boat is the Aquada, built by Gibbs Technology. Although, there are examples of car-boats dating back to the 1950's.