Date of Award

Fall 2024

Project Type

Thesis

Program or Major

Ocean Engineering

Degree Name

Master of Science

First Advisor

Igor Tsukrov

Second Advisor

David W Fredriksson

Third Advisor

Michael Chambers

Abstract

Entanglements in rope fishing gear significantly threaten the critically endangered North Atlantic Right Whale’s health and population (Knowlton, 2022; Brooker & Matthias, 2020). This thesis investigates the potential to mitigate the risk of whale entanglements in ocean structure tether components by using stiff fiberglass composite rods instead of rope. This potential was investigated through five main avenues:1. A survey was conducted of the availability, cost, and material properties of available composite rods and their operability in marine structures. 2. Four-point flexure testing was conducted to measure the degradation of the material properties of fiberglass composite rod samples as a function of deployment in ocean structures. 3. Tensile testing was used to evaluate the strength of the terminations and tensile stiffness of the fiberglass rods used in ocean structures. 4. The effects of the curvature characteristics of the leading edges of North Atlantic Right Whale (NARW) appendages were investigated with similarly curved bending element in three-point flexure testing against fiberglass rod. 5. The deformation of a marine structure consisting of fiberglass rod components under loading was measured. The results of these efforts suggest that fiberglass rods with terminations are usable in marine structures, although they present significant challenges as compared to rope. Of the tested varieties of fiberglass rod resin, the vinylester matrix varieties decayed the least with ocean environment exposure. The vinylester fiberglass rod deployed in the aquaculture structures of this project exhibited manageable amounts of structural degradation. Where tensile modulus testing results were valid, they produced results similar to those of bending modulus testing. The tested high-capacity termination assembly had a minimum tensile breaking strength of 80.1 kN, and the low-capacity termination assembly had a minimum tensile breaking strength of 25.4 kN. The results of flexure testing of NARW appendage leading edge curvatures against fiberglass rod showed that at these curvatures fiberglass rods could break, and did so in the cases considered in this project. Field testing showed that applying around 5.5 kN of orthogonal force to a grow line causes approximately 9.5 meters of deflection in the fiberglass grow lines of the Ram Island kelp farm.

Share

COinS