Equipment must be appropriately set-up and described to ensure as much consistency as possible among surveys and also to facilitate gear replacement if necessary. Equipment configurations can vary among substrate types. For example, in abyssal plains, wider skids on a beam trawl reduce sinking into mud. Table 8.1 lists the specifications, where available, of benthic sleds and trawls deployed in Australian waters.
The key components for a bottom trawl include the following, all of which should be documented and photographed:
- Sampling gear
- Net (full net plans, including mesh types and sizes)
- Floatation system (headline floatation plan, size, number, and position of floats)
- Groundrope (groundrope composition, length, details of all components)
- Rigging plans
- Sweep and bridle size and lengths
- Layback of the headline (if any)
- Deployment procedures
- Warp-to-depth ratios for amount of trawl wire
- Standard electronics to be used (e.g. USBL, CTD), and acceptable values of certain measurements
- Required towing speed
The key components for a benthic sled include:
- Sampling gear
- Net (full net plans, including mesh types and sizes)
- Frame (full frame plan, including dimensions and weight, chafing mat)
- Buoys (size, number, position)
- Mouth dimensions
- Rigging plans
- Bridle size and lengths
- Weak links
- Deployment procedures
- Estimated amount of trawl wire
- Standard electronics to be used, and acceptable values of certain measurements
- Required towing speed