RISK ASSESSMENT OF SMALL FISHING VESSEL TRAP NET OPERATIONS

This paper describes a means by which the capsize risk associated with various fishing vessel operating conditions can be evaluated. Rather than relying on the static restoring moment curve as the primary crite ria for vessel safety, modern nonlinear systems analysis is applied to the problem of extreme nonlinear rolling in random beam sea. While th e method is quite general and not limited to small vessels, it is illu strated with a specific application involving Native American trap net fishing on the upper Great Lakes. General trap net operations, as pra cticed by Native American fishermen and women in the Grand Traverse Ba y region, are presented in detail. The most significant characteristic of trap net operations is the heel induced during net deployment and net lifting. The increased risk to the vessel, in terms of the increas ed probability of capsize is quantified for various heel angles and va rious sea states. A significant advantage of the capsize analysis meth od presented here is its ability to investigate quickly the effects of many parameters (e.g., trap net line tension, wave height, and/or wav e period) on a nonlinear dynamic system without having to resort to ex tensive simulation studies.