Design Of Towed Transports Using Voyage Simulation Techniques

The planning, design and post analysis of towed transports can be undertaken using various simulation techniques. They can provide the designers and operators with a prediction of the likely forces, motions and weather (winds, current and waves) that the tug and tow may encounter prior to the decision to undertake a towed voyage. This paper will describe how the SafeTrans programme deals with the planning and design of tug-tow analyses and simulations. The ability of the software to utilise a global 18 year wind and wave hindcast and captain’s decision mimic which can take decisive actions, such as delaying departure, seeking shelter during a passage or avoiding a forbidden area or pirate coastline, use of multiple tugs and bunker stops during the towed transport, provide significant advantages to planners, designers and Tug-masters during real voyages. The paper will also discuss the results of comparison between data obtained from an instrumented real voyage with that of the simulation software undertaken over the same period and highlight any major differences in that data. The challenges faced by software developers in ensuring that simulations resemble real life realism with the probable decisions that can be taken by a Tug-master, such as the reduction of speed and/or alteration of course or the effects of tug-tow interaction and observed tug-tow motions or noises from waves and wind which cannot easily be replicated will also be discussed. In concluding, the paper will propose a way ahead for improving voyage simulation techniques including the collection of instrumented real time data during voyages for comparison with those of voyage simulation techniques in order to reconcile the two elements, improve the awareness of designers and operators and training of Tug-masters, to reduce risks and improve the standards of towed transports.