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Heave added mass and damping of a suction can in proximity to the sea floor

conference contribution
posted on 2023-05-23, 04:15 authored by Roe, T, Gregor MacFarlaneGregor MacFarlane, Drobyshevski, Y
Suction cans are usually deployed by the crane of a construction vessel, which must have adequate capacity to withstand the dynamic hook loads generated by motions of the vessel and heave response of the suction can. Before the structure is placed on the sea floor, it must be positioned above the target location; in this phase the suction can is manoeuvred into position being suspended in proximity to the sea floor. Hydrodynamic properties of the structure in the positioning phase are different from those experienced during the decent, due to the effect of the bottom proximity. As a result, the dynamic hook loads experienced in this phase may be also different from the deep water condition. The objective of this study is to quantify these effects; in particular the impact of the bottom proximity on the heave added mass and hydrodynamic damping. The added mass and damping of a 6-metre diameter suction can, of dimensions typical for Australian North West Shelf conditions, have been determined by testing a I: 10 model in the 4.2 m deep water tank of the Australian Maritime College. Free decay tests were conducted at several heave frequencies, and the heave added mass and damping determined. Four clearances of the model from the sea floor were investigated ranging from 1.20 to 0.20 of the can height. For each clearance, several sizes of open hatches were examined, by testing the model with 3 pairs of hatches of various diameters, with up to 4.8% of the relative area open. Model tests demonstrate that the heave added mass and damping increase as the suction can approaches the sea floor. Increase in added mass is found to be within 20% of its deep water value, and is made less pronounced by opening hatches of larger area. Linear (proportional to velocity) hydrodynamic damping also increases moderately as the under-bottom clearance reduces. Quadratic (proportional to velocity squared) damping is strongly affected, especially at very small clearances, with drag coefficient reaching unusually high values; this is attributed to substantial constraining effect of the bottom, which causes increasing flow velocities past the lower edge of the can. Results of the tests are presented, and their application for the installation lift analysis is discussed


Publication title

Proceedings of 27th International Conference on Offshore Mechanics and Arctic Engineering


CD Rom


Solomon Yim




Australian Maritime College


American Society of Mechanical Engineers

Place of publication


Event title

OMAE: International Conference on Offshore Mechanics and Arctic Engineering

Event Venue

Esroril Portugal

Date of Event (Start Date)


Date of Event (End Date)


Rights statement

Copyright © 2008 by ASME

Repository Status

  • Restricted

Socio-economic Objectives

International sea freight transport (excl. live animals, food products and liquefied gas)

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