Experimental Study On Hydrodynamic Characteristics Of Fishing Vessels Anchored Side By Side In The Harbor

Fishing harbors are important infrastructure for ensuring fishery production,they not only undertake the task of collecting and distributing fishing goods,but also provide a place for fishing boats to take shelter,and the safety of fishing harbor anchorage is closely related to the life and property safety of fishermen.The anchorage stability conditions of the anchorage in the harbor are very important for the safety of fishing boats,the violent movement of the moored fishing boat generate large mooring forces,which may lead to harbor accidents such as dragging anchor,broken cable,and collisions.Due to the small size of fishing boats,weak resistance to wind and waves,and high requirements for anchorage stability conditions,China’s current "Overall Design Specification for Fishing Ports"(SC/T 9010-2000)only provides the allowable wave height for fishing boats operating in front of the harbor,and there is no clear regulation on the allowable wave height for fishing boats anchored and avoid the wind in the port.However,in actual design,most of them refer to relevant foreign standards and combine engineering practice experience to provide,this has brought certain risks to the construction and use of fishing harbors.Due to the limitation of the effective water area in the harbor,fishing boats often adopt multiple boats anchored side by side.Under the combined action of nonlinear waves,currents,and waves,the coupled hydrodynamic problem of multiple boats anchored side by side is very complex.Compared with medium to large fishing boats,the nonlinear motion response of small fishing boats is stronger.However,there is currently less research on hydrodynamic related to the anchoring problems of small fishing boats at home and abroad,and there is an urgent need for systematic and in-depth physical model experiments and numerical simulation research.This paper takes a 100 HP small fishing boat as the research object,and conducts physical model tests under the action of regular waves,irregular waves,and their combined action for single-boat,two-boat,three-boat and four-boat side-by-side bow and stern anchoring.To analysis the effects of factors such as wave period,wave height,number of parallel fishing boats and direction of external load action on the motion response and mooring force of fishing boats.The results show that under the action of transverse waves or transverse waves combined with transverse currents,when the wave period approaches the inherent period of the fishing boat,a resonance phenomenon occurs when the fishing boat is anchored by a single boat.When multiple boats are anchored side by side,the roll motion response and mooring force of the fishing boat decrease with the increases of wave period,and the increase of the number of anchored fishing boats has a significant inhibitory effect on the rolling motion response of the fishing boat.Under the combined action of following wave or following wave combined with following current,the pitch motion response of fishing boats changes less with the increase of wave period,the mooring force of fishing boats decreases with the increase of wave period,the increase in the number of anchored fishing boats does not have a significant impact on the pitch motion response of fishing boats,while the mooring force of fishing boats increases with the increase of the number of fishing boats.The motion response and mooring force of the fishing boat under the following external loads are less than the transverse external loads.Compared with the anchoring test results of a 275 HP fishing boat,the resonance phenomenon of a 100 HP fishing boat during single boat anchoring is more obvious.As the number of fishing boats anchored side by side increases,the influence of ship size on the roll motion response of fishing boats is weakened.Based on the physical model test results of 100 HP and 275 HP bow and stern anchored single boats under transverse irregular waves,this article regresses the empirical equation for the roll motion response of anchored single vessels,providing technical support for further determining the mooring stability conditions of anchored fishing boats anchored in the harbor.