Resistance Analysis And Emergency Risk Assessment For Towing Of Large Marine Structures

Towage on the sea, which could be usually seen in shipping and oceanengineering, is a kind of special way of sea transportation. Huge ocean structuresoften have more investment and are easier to be caught in an accident; hence, it is fullof significance to guarantee the success of huge ocean structures’ towing.Some kinds of methods of resistance calculation and scope of their applicationare compared, and a practical format of calculation method is also put forward in thepaper. The resistance characteristics of heave plates of a truss spar platform will bediscussed by the way of CFD theory in the paper. On the foundation of the classicalflat plate theory, a new resistance coefficient which is suitable for larger scale andlarger Reynolds number is also summarised.According to the guidance of CCS and empirical formulas, a software ofcalculation and analysis on huge ocean floating structures’ towage was designed bythe language of VB.NET. The software can calculate huge ocean structures’ towingresistance, and indicate the distance between the tug and the tow after tug’s failure andfinally predict the collision time when some measures could be taken to decrease thedamage caused by the accident.The research and the example’s results show that, first, the resistance parameterof truss spar heave plate in wet towing is20%lager than that of small Reynoldsnumber flow. Last but not least, when the tug’s failure happens, the tug would stopand gain a negative speed in a short time because of the tow-line force, and thecollision will happen in several minutes. To cut the tow line in time to decrease theforce between the two objects could be an effective way to avoid more disastrousresults. The software is well designed and it is a kind of exploration in the field ofmarine towage.