Abstract: Method and apparatus for elevating an off-shore well drilling or other platform on a support structure in a minimum of time with maximum safety. The platforms are elevated on one or more caissons, utilizing one or more jacking units.One type of support structure comprises three caissons arranged as a tripod. The platform to be mounted thereon has three open caisson wells and is floated into position, with one caisson received in each well. A caisson locking gate is closed to hold the platform in place. A pre-set-up jacking unit is located near or straddles each caisson well. Each jacking unit includes a jacking head, one or more jacking legs pivotally connected at their upper end to the jacking head, and a jacking mechanism surrounding each jacking leg and connected by a gimbal joint at its lower end to the platform. A stabilizing frame for each jacking unit is mounted on the platform.