PARAMETRIC ESTIMATION OF ANCHOR HANDLING / TOWING WINCHES

摘要

Anchor Handling Tug vessels (AHT) are ships built to handle anchors for oil rigs, in addition to towing the platforms into position and in some cases operate as Emergency Rescue and Recovery Vessel (ERRV). Compared to ordinary offshore supply vessels, AHTs are characterized by large winches for towing and anchor handling, open stern for landing of anchors and a large bollard pull. The winch packages for anchor handling tug vessels are large and heavy constructions with weight that varies from 150 to 900 tonnes and may represent as much as 15% of the lightship weight for the vessel. In addition to significant weight, it also influences a lot on the vertical center of gravity (VCG) og thereby the stability of the ship. Also the longitudinal center of gravity (LCG) is significantly influenced by the layout and positioning of this equipment. Experience shows that it might be difficult to identify reliable weight and center of gravity (CoG) for this special made equipment from fabricators and suppliers in an early design phase. Based on this we want to study which parameters are relevant for estimating weight and CoG for anchor handling / towing winches, and how these parameters can be combined in mathematical formulas that can be used in regression based estimation. The advantage of using regression is among others the quantification of uncertainty (standard deviation) related to each specific estimation method and thereby the possibility to decide which methods that are the most precise, and to evaluate whether parametric estimation can be used at all. An evaluation of the uncertainty requirements will be performed as well. Stein Bj?rhovde is one of the founders and head of development of BAS Engineering. Mr. Bj?rhovde has a Master of Science Degree in Ship Design, and has been developing the weight engineering software ShipWeight since 1993. He has also been involved in development of other weight control software, in addition to being a consultant doing weight estimation and monitoring in the offshore industry. He has more than 15 years experience in weight estimation of new ship designs for several Norwegian and international ship designers and yards. Runar Aasen is one of the founders and technical sales manager of BAS Engineering, a SAWE corporate member. Mr. Aasen has a Master of Science Degree in Ship Design, has been extensively involved in the development of weight engineering software and user support for the last fourteen years, and became a SAWE Fellow Member in 2006. Since 1996, BAS Engineering has provided ship designers and builders around the world with naval architecture and mass properties support. BAS Engineering's ShipWeight software entered the US market for the first time in 1998 and has since been adapted by major US shipyards and designers.