Simulation of Launching and Self-Upending of a Spar Hull

Abstract

The goal of this research is to develop an effective and efficient plan for the installation of a spar using the barge launching method. Relative to the conventional method of installing spars, the barge launching method enables the elimination of some operations and therefore has the potential to reduce installation costs and schedule.

Through numerical simulations based on fundamental equations of motion, the trajectory analysis of the spar and barge during all stages of the launching and spar upending process is performed to verify that the spar, as designed, can be safely installed using the barge launching method.

The derivation of the equations motions based on conservation of momentum and use of free body diagrams is provided. The coupled equations of motion are integrated in time and the results are sufficiently reasonable to understand the global behavior of the dynamics of the spar and the barge on the sea. The numerical time integration of the matrix system of equations is performed using Matlab ODE solver based on fourth and fifth order Runge-Kutta formulas. A detailed flow chart for the simulation procedure is provided.

Two basic launching scenarios are considered: launching from the top of the spar and from the bottom of the spar. For each of these launch scenarios, three cases involving different trim angles and kinetic friction coefficients are investigated. Based on detailed analysis of the simulation results it is concluded that although both launch scenarios may be feasible, the bottom launch scenario occurs at slower speed and is therefore preferable.