A boat lift can save you maintenance by keeping your boat at the water, but out of the water, and is perfect if you have your own private dock. The simplest boat lift you can make is a pair of davits, the small cranes used to lift lifeboats over the side of a ship. The davit is little more than two welded steel beams of sufficient strength to withstand the strain of lifting of your boat from the water, and "boat falls," the block and tackle, usually a twofold purchase, hooked to the boat and used to lift the boat from the water.
Cut one end of each of the 5-foot and 10-foot "I" beams at a 45-degree angle with the cutting torch. Weld a 5-foot "I" beam to a 10-foot "I" beam at the cut edges of the beams. Repeat this process with the additional "I" beams to form the davits.
Use the drill press to drill 1/2-inch holes in each corner of both steel plates. Weld a flat steel plate to the bottom of each 10-foot beam.
Weld a steel eye bolt onto the end of the 5-foot "I" beams. This eye bolt will be used to suspend the riven tackle.
Bolt the davits to the dock walkway or pier. The davits should be one boat-length apart, based on the length of your boat.
With the line, reeve a twofold purchase in the blocks. Hang the blocks from the eye bolts on the davits. Screw an eye bolt into the forward structural member (the stem) and into the after structural member (the main frame or transom frame) of your boat.