Gone Outdoors

How to Put a Boat on Blocks

by Will Charpentier

During the winter season, when the boat maintenance part of boating is on your mind, you may want to move your boat from its trailer and onto blocks for several reasons, most of which center on repairs to the underside of your boat. With the aid of two people and one additional vehicle, moving the boat up on blocks offers you the opportunity not only to paint the boat's bottom, but also to paint and repair the boat trailer.

Pull the boat and trailer to the location where you plan to put the boat up on blocks. Leave the trailer hitched to your vehicle. Disconnect the trailer winch from the boat.

Set the blocks on the ground, one block every every three feet, where you will position the keel. Back the trailer over the blocks so that, even though the boat is still on the trailer, the blocks are under the keel. The blocks should be tall enough to keep the keel of the boat -- the center of the bottom -- off of the ground surface beneath.

Position another vehicle and driver behind the boat, 10 feet or more from the blocks on which the boat will rest, so that the blocks are between the boat and the second vehicle. Tie one end of two polypropylene lines to to the second vehicle's bumper using simple slip knots. Tie the other ends of the lines to the tie-down rings on the transom of the boat, keeping the lines as taut as possible.

Pull the trailer straight away from the second vehicle very slowly. The taut lines on the second vehicle will restrain the boat, preventing its forward motion with the trailer and allowing it to slide from the trailer onto the blocks, as if it's being launched at a boat ramp. Position your second assistant so that person can watch the progress of the boat onto the blocks and tell you when the boat's keel first makes contact with the blocks. Stop your vehicle when the boat makes contact with the first set of blocks and reposition the rest of the blocks as necessary. Place jack stands under the bottom on both sides of the keel, to keep the boat from tipping over. Continue to pull forward, stopping to place a pair of jack stands -- one on each side of the keel -- every four feet.

Once the boat is on the blocks, supported in position on both sides by jack stands, screw trailer tie-downs into the ground on both sides of the boat. Tie one end of each of four natural-fiber lines, manila or sisal, one to each of the two bow cleats and one to each of the two stern cleats. Then, tie the other end of the lines to the trailer anchors, pulling the lines tight at the trailer anchors, so that the boat is leveled and secured by the lines.

Items you will need
  • Blocks, sized to hold the boat off the ground.
  • 2 assistants
  • 1 additional vehicle
  • Polypropylene rope
  • Trailer tie-downs
  • 4 natural-fiber ropes, either manila or sissal


  • Once the work is complete, return your boat to its trailer by raising the tongue jack to its greatest upward position. Back the trailer to the boat using another person to guide you, so the trailer and boat are lined up, just as if you were pulling up on the trailer at the boating ramp. Hook the line from the trailer winch to the eye on the bow of the boat and pull the boat onto the trailer with the winch. Lower the tongue jack.


  • Nylon rope has a potential for "snap back," just like a rubber band, with catastrophic effects if the line parts. Polypropylene -- plastic line -- won't snap back; it simply breaks when too great a load is placed on it. A 3-inch polypropylene line can haul 3 tons -- 6,000 lbs. -- safely. If your boat weighs between 10 and 2,000 lbs., use 1-inch line. If it weights between 2,000 and 3,000 lbs., use 2-inch line.


  • "The American Merchant Seaman's Manual"; W. Hayler; 1981

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