Design of the Propulsion System for the Autonomous XLUUV MUM

Abstract The paper reports on one aspect in the design of the extra-large unmanned underwater vehicle (XLUUV) MUM, referring to a large Modifiable Underwater Mothership. The vessel will be highly modular and has unique features, such as hydrogen fuel cell and lithium-ion batteries. Modules can be added and rearranged to fulfill different operations. The envisaged operation scenarios pose a challenge to the design of the propulsion and maneuvering system. Due to the limited power and energy storage, it must be efficient during submerged transit, capable of safe surfaced operation in public sea routes and of dynamic positioning. A design study is presented based on an initial design of two variants. The basic hull forms are compared in terms of required forces and moments for vessel motions. Simulations of hull forces are conducted using Reynolds-averaged Navier-Stokes (RANS) equations and vessel motions are determined with an actuator force model. Different arrangements of propulsors and thrusters are investigated and compared concerning their propulsion efficiency and their agility in translatory and rotary directions. The results are presented as tabulated data and in capability plots. A final design is presented and discussed and a conclusion is presented.