Pilot's Tug Assist Tool Provides Bollard Pull Calculations
Captain M.Baykal Yaylali, chief pilot at the Directorate General of Coastal Safety Izmir Alsancak Port, has released open source software Pilot’s Tug Assist Tool (PTAT) which estimates the total required tug power for ships in various conditions of wind, current and waves. The tool can be loaded as an app on a smart phone.
In most cases, the required tug power and number of tugs needed in variable conditions of wind, current and waves is an assessment made by pilots based on their professional experience. However, these assessments can be questioned by lawyers if something goes wrong. Additionally, a pilot has not so much time, says Yaylali. “For a pilot, if tugs are needed, it is hard to calculate the required tug power just before or during ship maneuvering. Furthermore, the more extreme the weather conditions become the less accurate assessments are and the higher the risk of too little tug power.”
The tool is based on the calculations and graphs as explained in Chapter 5 of the book “Tug Use In Port” written by Captain Henk Hensen FNI; first published in 1997 by The Nautical Institute, London, UK, with a third edition published by The ABR Company in 2018.
The program has been tested for more than two years, and it has been working well, says Yaylali.
Safety factors have been added to the program that will factor in 20 percent for current effect and 25 percent for wind and wave effects. It is possible to convert calculations for possible bow and stern thrusters (kW-HP) and for wind (KT-m / s). In addition, for scenarios concerning hazardous cargo that require compensating for sideway/lateral ship momentum, users can calculate the tug/pull power output to be applied 30 meters before the dock/docking. Calculations can be performed for open and solid berths separately.
The app is available free of charge, and more information is available here.