Page 53: of Maritime Reporter Magazine (March 2017)

SHIP SIMULATOR ber of key building blocks. A module was tion is the tuning of the various compo-

By Pepijn de Jong developed based on added mass planing nents and coef? cients in the underlying theory (or ‘momentum theory’) as was computational building blocks. For the ouncing over the waves at a speed pioneered in the 1930s by Von Karman FSSS project, MARIN made use of the of 43 knots, the director of the De- and Wagner. Experience from recent re- know-how that it has been building up

Bfense Materiel Organization (DMO) search in the DROPSIM tool develop- over the past years about small, fast craft

Vice Admiral Arie Jan de Waard, and ment program into modeling the impact and RHIBs. This includes various model

MARIN’s director Bas Buchner, made of free falling lifeboats into the water tests with fully remote controlled mod- the ? rst test voyage on the moving ‘Fast surface also contributed. In this approach els of high-speed small craft in the Sea-

Small Ship Simulator.’ This FSSS is built the ship is split into a number of 2D keeping and Maneuvering Basin and the

Real-time visualization by MARIN and SME partners, Cruden transverse sections and the impact force development of advanced computational and simulation technology and TreeC, as part of a CODEMO project of each of the sections is determined methods such as PANSHIP.

to stimulate the development of a proto- based on the impact velocity and wetted In the development phase of this proj- type. Vice Admiral De Waard felt the test shape of each section at each time instant. ect, RHIB instructors from the Royal was very realistic and said: “You feel as if The method is based on ? rst principles Netherlands Navy were invited to give you are involved in a complex operation at and proves to be very adequate in deal- their feedback on the behavior of the sea. Virtual reality like this is going to play ing with both planing in calm water and computational model in combination a large role in education and training.” impact forces on fast vessels in waves. with the motion system. During various

Another building block deals with the workshops, the instructors have been

Detailed Replica RHIB Console hydrostatics and wave forces, computed testing every aspect of the simulator, in-

A unique knowledge combination led to on the actual submerged geometry. The cluding steady trim in calm water, steer- the FSSS, which is made up of a motion resistance was also modeled as a func- ing and throttle response, turning circle base, typically used for racing car simu- tion of ship speed and actual submerged diameters, the roll angle during turning lations (Cruden), real-time simulation of wetted surface. A detailed engine model and the motion behavior in waves from ship dynamics (MARIN) and an advanced is included to simulate the dual Z-drive every direction. Even aspects like the visualization environment (TreeC). The setup, including the effect of trimming forming of spray on the visualization, main goal of the FSSS project is to pro- the Z-drives. A coef? cient-based maneu- friction between the RHIB and ves- vide a safe but accurate environment for vering model to cope with the horizontal sels during boarding operations and the training drivers and navigators of Rigid plane motions and additional damping engine sound were discussed and im-

Hull In? atable Boats (RHIBs). The mo- coef? cients complete the model. proved. This approach makes this proj- tion platform has been out? tted with a near ect truly unique, resulting in a valuable exact representation of the control console simulation and training tool for opera-

Navy Input of the actual RHIBs used by the Royal

An important step in real-time simula- tors of RHIBs and other fast small craft.

Netherlands Navy. This includes engine controls, VHF radio and a GPS system.

Even the seats of the driver and navigator are exact copies of the actual seats.

To facilitate simulation of fast RHIBs,

MARIN extended its simulation frame- work (XMF) with a new approach to simulate complex phenomena such as slamming, capsizing, surf riding and broaching. The main challenge was to de- velop a method capable of simulating such complex motion dynamics while at the same time providing predictions in real- time, including the effect of control inputs by the operator. A balance had to be struck between ‘accurate enough’ and fast com- putation times. The method also had to be robust to cope with a wide variety of possi- ble conditions and inputs, and also provide realistic motion predictions at all times.

XMF

Based on recent experience a com- putational model was built up from the ground within XMF consisting of a num- www.marinelink.com 53

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