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High-level demonstration of holistic design and optimisation process of offshore support vessel
Published in Pentti Kujala, Liangliang Lu, Marine Design XIII, 2018
M. de Jongh, K.E. Olsen, B. Berg, J.E. Jansen, S. Torben, C. Abt, G. Dimopoulos, A. Zymaris, V. Hassani
When setting up the case, information about the mission and the crane type must be provided in addition to definition of the design space that shall be explored using a parametric hull model (Step 1). For each hull size, steel weight is estimated (Step 2) before stability calculations are performed taking into account the heeling moment from the crane operation. This is resulting in a go/no-go decision (Step 3). Vessel motion performance is calculated defining a limiting weather criteria taking into account the active heave compensation performance of the crane (Step 4). Station keeping calculations are performed to define the required thrust forces fore and aft of the vessel in Dynamic Positioning (DP) operation (Step 5). Resistance of the hull is calculated to dimension the main propulsion requirements for the vessel in transit operations (Step 6). Based on the thrust and propulsion needs, the propulsion and thruster units are selected (Step 7). Fuel consumption is estimated based on a simplified operational profile and a power system setup adapted to the selected propulsion and thruster units. High level estimates of CAPEX and OPEX can then be calculated (Step 8).
Modeling and analysis of active heave compensation control in marine cranes
Published in Fei Lei, Qiang Xu, Guangde Zhang, Machinery, Materials Science and Engineering Applications, 2017
On the basis of the analysis of the active heave compensation principle, a scheme of marine crane active heave compensation control system is designed, as shown in Figure 4. It is made of four parts: control, sensors, hoist, and the hydraulic drive mechanism. By stretching or compressing the piston rod to change the absolute displacement of lifting position, the hoist pull, or unclamp sling at a speed, the sling changes the heavy object’s displacement through fixed pulley on the hydraulic cylinder piston connected to the heavy objects, thereby realizing the displacement compensation.
Study on the system design and control method of a semi-active heave compensation system
Published in Ships and Offshore Structures, 2018
Mingjie Li, Pan Gao, Junliang Zhang, Jijun Gu, Yingjin Zhang
A passive heave compensation system is usually configured with an accumulator connected to the hydraulic cylinder, which is very simple in structure. It acts as a hydraulic spring and does not need external power supply. However, the compensation accuracy is low, the hysteresis is large, and the compensation force from the accumulator makes the system unstable. An active heave compensation system adopts feedback control and needs external power supply to actuate the hydraulic cylinder. The active systems have good compensation performance and better stability; however, they have high energy consumption and costs.