Recently, process platforms and drill ships featuring anchor sea-keeping system equipped with a turret arrangement have increasingly been proposed for deep-water offshore applications to be operated in freezing seas. A possibility of environmentally-oriented yawing with the ship’s bow ahead of the resulting vector of environment actions provides the major advantage of the turret system use. The turret system allows passive positioning of the ship without activation of any propulsion means or thrusters, which is particularly important in ice conditions where ship controls can be difficult to operate.

CDB Corall PJSC designed a promising turret-based drill ship (TBDS) intended to perform drill operations in seas of Russian Arctic region. The design is substantially different from drill ships and platforms conventionally considered for similar purposes. The adopted design solutions ensure significantly higher drill ship performances in ice conditions.

The report includes results of TBDS model tests performed in the model basin of the Federal State Unitary Enterprise “Krylov State Research Centre”. Tests of ice resistance and tension of the anchor sea-keeping system have been incorporated in the test program, while the model was being interacted with the variable-thickness ice sheet at a 0° heading. Testing to investigate behavior of the interacted with ice ridge formations have also been performed at the same heading.

The study of passive model yawing at 90° and 170° conditions made up a highly important part of the program. Such tests were performed both for model/ice sheet and model/ice ridge interaction types. In addition to measuring force parameters during the tests, changes in heading, heel and trim, as well as model displacements were also determined. Testing proved high ice resistance and maneuverability of the test model.

The report includes comparison of the results obtained in model basin tests with other experimental data for models fitted with turret arrangement and anchor sea-keeping system features. The comparison suggests considerable advantages of the new solution versus previously considered options.

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