Abstract: Locking devices for surfboards, sailboards and skateboards which clamp about tapered sides of surfboards and sailboards adjacent the fins. The devices clamp about skateboard sides between the two sets of wheels. One version has a hook ended rod that grips about a board side and another end that attaches by a padlock to a second rod which hooks about another board side. The first rod end has through holes that insert into a cylinder end of the second rod. The further one rod is inserted into the second cylindrical rod end, the closer the spacing between the hooks. A padlock in the through-holes connect the rods. Another version has a padlock in the second cylindrical rod where grooves on the first rod end are locked in place. Another version has a perpendicular extension bracket that wraps about one surfboard or sailboard fin. Another version uses a top flat plate that hingedly connects to a curved bottom plate. Opposite ends of the plates have matching through-holes for a padlock.