Steady Current Forces On Tanker-based FPSOs
Author(s)
R. S. Mercier & F. A. Huijs
Abstract
There is very little information available in the public domain on steady current
forces on tanker-based Floating Production, Storage and Offloading systems
(FPSOs). The general lack of available data and unresolved issues related to
scale effects in model tests bring into question whether the level of uncertainty in
modelling of current forces on FPSOs is sufficiently well understood, which has
implications for the design of FPSO station-keeping systems. This paper
presents the results of a test program to measure current forces on a tanker-based
FPSO at various current speeds and relative current headings. While the results
are in general agreement with the design curves published by OCIMF, there are
some important differences associated with the effect of bilge keels and the
effect of lift forces generated by vortex shedding from the bow and stern.
Keywords: current forces, tankers, FPSOs, scale model tests, bilge keels.
1 Introduction
Steady forces exerted by ocean currents on deep draft, column-based structures
such as tension leg platforms or spars are relatively straight forward to estimate
using textbook information on bluff body drag. In the case of tanker-based
Floating Production, Storage and Offloading Systems (FPSOs), there is very
little public domain information on drag and lift forces in steady currents that can
be used for routine design calculations.
Remery and Van Oortmerssen [1] presented a method to predict current
forces on moored tankers based on several model tests conducted at the
Netherlands Ship Model Basin (currently MARIN). Since the authors felt the
small longitudinal forces were not measured with sufficient accuracy, they
proposed that the ITTC-1957 frictional resistance formula be used to predict the
longitudinal force. For the transverse force and yaw moment coefficients they
Keywords
current forces, tankers, FPSOs, scale model tests, bilge keels.
Related Book
Other papers in this volume
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