My father ownes a large sales and service yard with a 55 ton travel lift. I have helped raise several boats including barges. THE best way to raise a boat is with blowers. It is MUCH easier to push air in than to pull the water out. You can push a much greater volume of air into the hull than you can pull water out. They used to use several 3 and 4 inch pumps at once, now they use mosly blowers and only use the pumps to remove the water once the hull is up.

A big thing to remember when raising a hull is to plug ALL openings in the hull before trying to raise it (assuming you are trying to float it). Once you get the water out, you want to keep it out.