They look complex, but submersible platforms are basically multi-jointed arms, usually fabricated of marine-grade stainless steel, bolted to the transom and capped with the fiberglass platform itself. Each arm is raised and lowered by a hydraulic cylinder, and is cleverly designed to keep the platform level as it rises and falls. The hydraulic pump is mounted inside the boat, along with the control boxes, wiring, and so forth. Installation isn’t a do-it-yourself job. here