Jack stands should be placed as far out from the boat as practical to support the boat in high winds, with at least three per side for boats over 26 feet and additional supports at overhangs. Storing cradles in the off-season is problematic at crowded boatyards, which instead rely on a combination of screw-type jack stands, blocks, and timbers to support hulls.
The weight of the boat can easily force a jack stand base deep into mud, sand, or asphalt. Even clay that seems brick hard can become a quagmire in heavy spring rains, allowing stands to loosen, shift, and spill the boat. Placing a sheet of plywood under each base and using safety chains to connect the stands will help to stabilize the support upon which your boat rests. Jack stands stabilize the boat, but most of the boat’s weight usually rests on its keel. Some boats have specific requirements to support the keel, and at least one manufacturer warns against putting weight on the keel. If the marina manager isn’t familiar with your boat, check your manual or contact the manufacturer. Keels must be supported by wide timbers or blocks – the wider the better to distribute the load.