Jaroslaw Artyszuk

Steady-state Manoeuvring of a Generic ASD Tug in Escort Pull and Bow-rope Aided Push Operation

This paper is devoted to expand the very promising research undertaken in the authors previous work, basically done on simplified modelling the escort push operation. Now, the other two modes of a tugs employment, as stated in the title, are covered. The special focus is again set on the indirect towing in that the towline force is much higher than the thruster force. The ratio of these two forces, referred to as the relative towing force (or amplification ratio) is evaluated together with the hull drift angle and the thruster(-s) angle for a given escort speed. This mutual relationship is known as the tug performance diagram. Although rather generic (container-type) formulas are derived, they are supplied for exemplification purposes with simple, analytically given hull hydrodynamic forces. The aim is also here to provide a basis for further sensitivity analysis of the model and possible improvement/optimization to the tug design. The obtained charts also could serve as rough and clear guidance for towmasters while escorting.

System for Determining Dynamic Under Keel Clearance of Vessels Entering the Port of Swinoujscie (DRWPS)

The article presents a system for determining dynamic under keel clearance. In order to build a DRWPS system, a mixed model was created based on the analysis of math models. The system includes advisory software for defining the conditions for the entering of large LNG vessels in the context of under keel clearance and software was built to support the decision‐making of operators who are responsible for introducing these vessels to the Port of Swinoujscie. http://www.transnav.eu the International Journal on Marine Navigation and Safety of Sea Transportation Volume 11

Inherent Properties of Ship Manoeuvring Linear Models in View of the Full-mission Model Adjustment

The paper presents new results on the inherent properties of ship linear dynamics. The focus is made on the second‐order formulation for the uncoupled equations of sway and yaw, and on their unique, unknown performance within the zigzag test. From the standpoint of application to full‐mission model tuning, a very important loop in the drift‐yaw domain of the zigzag behaviour, as governed by the rudder rate dependent time constants (of T3‐type), is brought to the light. This and some other dependent effects, like overshoot angle performance, are likely to be lost, if the well‐known, rather ambiguous, first‐order approximations are deployed. http://www.transnav.eu the International Journal on Marine Navigation and Safety of Sea Transportation Volume 10 Number 4 December 2016 DOI: 10.12716/1001.10.04.08

Peculiarities of zigzag behaviour in linear models of ship yaw motion

Abstract The present survey, as part of larger project, is devoted to properties of pure linear models of yaw motion for directionally stable ships, of the first- and second-order, sometimes referred to as the Nomoto models. In rather exhaustive way, it exactly compares and explains both models in that what is being lost in the zigzag behaviour, if the reduction to the simpler, first-order dynamics (K-T model) is attempted with the very famous [Nomoto et al., 1957] approximation: T = T1 + T2 - T3. The latter three time constants of the second-order model, more physically sound, are strictly dependent on the hydrodynamic coefficients of an essential part of the background full-mission manoeuvring model. The approximation of real ship behaviour in either of the mentioned linearity orders, and the corresponding complex parameters may facilitate designing and evaluating ship steering, and identifying some regions of advanced nonlinear models, where linearisation is valid. As a novel outcome of the conducted investigation, a huge inadequacy of such a first- -order model for zigzag simulation is reported. If this procedure is used for determining steering quality indices, those would be of course inadequate, and the process of utilizing them (e.g. autopilot) inefficient.