Controlled Launch Offloading of Holstein Spar Truss Section

摘要

The Holstein truss spar hull, the largest ever built, wasrnfabricated in two sections in Finland and the U.S. The Trussrnsection with the soft tank was fabricated in the U.S. andrnrequired transferring from land to water at the fabrication yardrnbefore it could be mated with the hard tank section. Thernchallenges due to the size, schedule and governmentrnregulations resulted in selecting a unique controlled launchrnsubmergence method to offload the truss section into thernwater. The offloading operation involved inclining the H-627rnlaunch barge to unusually high angles while ballast operatorsrnwere onboard the vessel, moving the truss down the barge in arncontrolled fashion with winches rigged to skid shoes andrnfinally submerging the barge to create separation. The trussrnsection was loaded on the barge from the bow and launchedrnover the tilt beam at the stern. Discontinuous removable skidrnshoes were used instead of traditional continuous permanentrnlaunch cradles.rnThe truss section travel over the barge, and speed controlrnduring launch was achieved by employing two sets ofrnwinches, Pull Winches and Hold Back Winches, located onrnthe Barge Deck. Structural modifications had to be made tornthe barge, skid beams and soft tank structure to make thernoperation feasible. Additional barge marine systems had to bernadded for the unusual ballasting and floating configurationrnrequired for the operation. An active mooring system alongrnwith the winch line tensions was used to control the barge andrnthe truss during the operation.