Estimating sea vessel’s braking distance influenced by wind and waves

The article considers the methods of estimating the wind effect on the braking characteristics and the vessel behavior under the wind and waves. A model with regular sea waves is illustrated, in which the wave ordinate changes according to the sine law. It is stated that in reality the wave ordinate varies approximately by the sum of an infinite number of harmonics, the so-called irregular excitation. There are given differential equations of wind effect on the inertial-braking characteristics, of braking, of calculating the braking distance, etc. There has been estimated the braking distance of the motor vessel “Yuri Maksarev” with four rows of containers in headwinds up to 15 m/s. The wind has been proved to influence greatly the length of the braking distances, with the length of braking distance becoming two cables less after three minutes. The diagram of the apparent wind influencing the ship is presented. The apparent wind impacts the vessel’s hull above the waterline. Drift angle estimating is performed using a programmable calculator, a table or a nomogram. There is proposed a nomogram that greatly simplifies preliminary calculating and reduces the time costs. There have been compiled the programs for calculating the wind drift angle and constructing the corresponding nomogram in the application Microsoft Excel 97 using the programming language Visual Basic. The developed programs allow automating the most frequently performed calculations for determining the angle of wind drift, for which little time is needed during the maneuvering process. The arrangement of the diagram on the paper is illustrated, the process of building a nomogram is presented in stages. A case of the calculated nomogram for the motor ship “Yuri Maksarev” has been presented.