Abstract: The Removable Bottom Founded Structure (RBFS) is an offshore platform for petroleum drilling and producing operations intended for depolyment in waters with severe weather and iceberg conditions. The structure is normally held down by gravity, but during the deballasting procedure a hold-down system is employed to keep the platform on the subbase until site evacuation. The system that is used to hold the platform down onto the subbase is located where the platform meets the subbase. It operates on the principle of hydrostatics. On the underside of the columns there are multiple chambers which may be evacuated by pumping and which are vented to the outside atmosphere. Flexible seals that define these chambers are positively engaged by this evacuation to create a fluid-tight seal so that no seawater will enter the evacuated chambers. The reduction of the buoyancy forces will hold the platform onto the subbase until such time as the platform is totally deballasted.