UNCERTAINTY OF SEA TRIALS RESULTS USED FOR VALIDATION OF SHIP MANOEUVRING SIMULATION MODELS

Increasingly complex marine operations dictate higher need for precise and reliable modelling. For the last decades several different approaches to modelling of ship manoeuvring were developed, including scaled model testing, numerical and empirical methods. Increasingly, time-domain simulation models for ship manoeuvring are developed and used for training and planning of marine operations. Especially when using the simulation models to plan operations, it is essential that the simulation model is properly validated. There is a need for better and more standardized validation methods for such simulation models. A key issue is the uncertainty of the data used in the validation. Typically, the validation will be against full scale trials results. In the study reported in this paper it was found by inspection of repeated tests results that even under relatively calm environmental conditions outcomes of sea trials can be highly uncertain. However, it is very expensive to investigate uncertainty of each type of trial experimentally. Therefore it can be very beneficial to estimate it by means of a simulation model. This paper presents results of analysis of full scale turning circle trials of research vessel "Gunnerus". Turning circle trials with 20 degrees and 35 degrees rudder angle executed both to starboard and port sides are analyzed. Experimental uncertainty analysis is performed. Effectiveness of IMO correction procedure is discussed. Also paper describes a method for determining uncertainty of trial results due to environmental effects by means of simulation model and compares them with experimental uncertainty. The method is based on Monte-Carlo techniques.