How to Build Your Own Boat Lift

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.

Things You'll Need

• 2 steel "I" beams, 4 inch x 10 foot
• 2 steel "I" beams, 4 inch x 5 foot
• 2 Flat steel plates, 6 inches x 6 inches x 1/2 inch
• Cutting torch
• Welding machine
• Drill press
• 1/2 inch steel bit
• 2-sheave blocks
• Nylon line
• Steel eyebolts

Instructions

1. 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.

2. 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.

3. 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.

4. Bolt the davits to the dock walkway or pier. The davits should be one boat-length apart, based on the length of your boat.

5. 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.

Tips & Warnings

• When you wish to lift your boat, bring it alongside the dock walkway or pier, attach the boat falls to the eye bolts on the front and rear of the boat, and raise the boat using the falls.

• Working with welding, cutting and drilling equipment carries its own set of hazards and appropriate caution is urged. Do not attempt to lift an occupied boat from the water.

References

• Practical Shipbuilding; A. Holms; Longmans, Green, 1908 p. 380 ff
• The Bluejacket's Manual, Naval Institute Press, 1951

Resources

• Read this Article in Spanish
• Chapman Piloting and Seamanship