Flume tank Statement of need.pdf

STATEMENT OF NEED FOR SERVICE

NOAA Fisheries Alaska Fisheries Science Center / RACE Division

2025 Flume Tank Studies in St. John’s, Newfoundland and Labrador, Canada

PURPOSE:

The Resource Assessment and Conservation Engineering (RACE) division at NOAA Fisheries’ Alaska Fisheries Science Center currently conducts various fisheries research surveys in the eastern Bering Sea, northern Bering Sea, Bering Sea slope, Chukchi Sea, Aleutian Islands, and Gulf of Alaska regions. The primary sampling tools for these surveys are the 83-112 and Poly Nor’easter bottom trawls, both of which are constructed with five-decade-old technologies and materials. These trawl materials are becoming increasingly difficult to acquire, and must be obtained through high-cost special orders and custom contracts in order to continue the construction and maintenance of such specialized research equipment. These increased costs of trawl construction materials, the sheer variety of materials needed for these two different and unique trawls, as well as overall advancements in modern-day bottom trawl technologies are ultimately compelling the RACE division to examine both the modernization of our survey trawls and also the possible implementation of one primary sampling trawl that can be standardized across all RACE bottom trawl surveys.

The goal of this work is to test model prototype trawls in a flume tank to facilitate the selection of a universal survey trawl. Flume tank testing allows us to evaluate trawl performance under a range of simulated towing conditions at a fraction of the cost required to test full-scale trawls in the field. Furthermore, flume tank testing allows simultaneous monitoring of all aspects of trawl performance and geometry, which is not possible through field testing. These studies will also allow us to improve trawl gear protocols, decrease material costs, reduce deployment and retrieval time, and select a design that reduces variability in catch efficiency. These improvements will allow a larger area to be sampled within survey time constraints and improve the precision and accuracy of survey data products that are used for stock assessment of Alaska fisheries to meet regulatory requirements for fishery management under the Magnuson-Stevens Fishery Management and Conservation Act.

Stan Kotwicki (study lead) and collaborators Nicole Charriere, Sean Rohan, and Shawn Russell previously conducted flume tank studies to establish trawl performance baselines of current AFSC bottom trawl survey gear on January 13-18, 2025 at Memorial University in St John’s, Newfoundland, Canada under contract 1305M324P0183. We also awarded a contract to a trawl manufacturing company, NET Systems, to provide an industry-standard trawl design and consultation for the flume tank studies, contract 1305M3240191. During testing of the industry trawl, we observed that additional design modifications are needed to achieve a universal trawl that meets performance requirements for AFSC bottom trawl surveys.

RACE Trawl:

Analyses of flume tank data revealed that the industry trawl design needed to be modified to meet survey requirements. Such as shorter body design with less web to reduce repair times, 3rd bridle to support the side panels to reduce slack web in the wings and front end of the body. Under the current consulting contract listed above, we consulted with NET Systems to plan design modifications to the industry trawl that would more thoroughly incorporate key attributes required for a survey trawl.

Poly Nor’easter:

Baseline flume tank experiments with the Poly Nor’easter revealed the trawl demonstrated satisfactory performance under simulated towing conditions and most of the key attributes that are required for the Bering Sea surveys. The primary deficiency was that the Poly Nor’easter did not have adequate bottom wing length that is required for Bering Sea surveys.

Through consultation with NET Systems, the Poly Nor’easter was redesigned with bottom wings to meet required specification for the Bering Sea surveys.

This is a purchase to manufacture two (2) 1/8th scale model trawls (RACE Trawl 3-bridle & redesigned Poly Nor’eastern) and conduct three (3) days of flume tank testing at a flume tank facility.

TECHNICAL SPECIFICATIONS:

The flume tank facility must be capable of manufacturing 1/8th scale model trawls (including codends) of the RACE Trawl 3-bridle and the redesigned Poly Nor’easter trawl.. They will also be required to supply multiple bridle configurations determined by RACE scientists for testing trawls in the flume tank. The flume tank must be capable of producing a continuous flow rate of 1 m/s. The flume tank must be capable of producing both full HD video and digital stills during the experimental trials, as well as documenting all flume tank settings.

DELIVERABLE SCHEDULE:

The Contractor will provide three (3) full days (7 hours per day) in the flume tank, including flume tank facility costs, staff (three employees), and project management. Deliverables include digital still pictures, unedited HD video, and data sheets containing data collected during the flume trials (e.g., water flow, measurement of headrope height, upper and lower wing tip spread, gear geometry calculations such as angle of attack, door spread, over spreading with reduced bridle lengths and under spreading with standard bridle lengths). Flume tank staff will work with NOAA staff after the tank testing to verify and correct data, which shall be delivered to NOAA staff within one week of completion of the flume tank work.

The period of performance 8/01/2025 to 4/30/2026

TECHNICAL POINT OF CONTACT

Shawn Russell Marine Equipment Supervisor RACE Division E-mail: shawn.russell@noaa.gov

(206) 228-8446