Towboard
A towboard is a piece of aquatic survey equipment consisting of a board attached to a rope that is towed by a surface vessel. It is used to tow one or more divers underwater at a constant depth to survey bottom features such as coral reefs. The diver may use a scuba set, or if only a snorkel, may remain at the surface, or travel underwater for around two minutes.[1]
The surface vessels travels at approximately 1 to 2 miles per hour and may tow two divers, one with a camera pointing down, and other with a camera facing forward. by a surface craft. The boat follows a depth contour to keep the towboard over a specific depth. The divers can also maneuver the board to maintain a more precise depth and avoid obstacles. A survey may cover about 2 miles over a period of around 50 minutes.
This type of surveying method is called a towboard survey, towed-diver survey,[2] and the manta tow technique, the latter named after the Manta Board, an oval towboard marketed for recreational use.[3][4] A variant is the SAM or "Single-armed Manta-board". This consists of a small board with a strap to secure and tow the diver by the forearm. This frees the other arm, allowing the diver to take notes on a pad held by the towing arm.[5]
The use of a towboard is considered safe up to approximately 90 feet. Beyond that, the divers would require decompression.
Towboards may be equipped with a GPS and sensors to record the temperature and depth every few seconds. [6][7][8]
References
- ↑ http://www.aims.gov.au/334
- ↑ https://data.noaa.gov/dataset/cred-towed-diver-benthic-characterization-survey-at-niihau-main-hawaiian-islands-in-2010
- ↑ http://www.unesco.org/csi/pub/source/rs12b.htm
- ↑ http://www.aims.gov.au/334
- ↑ http://spo.nmfs.noaa.gov/mfr562/mfr5623.pdf
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External links
- Crown-of-thorns starfish and coral surveys using the manta tow and scuba search techniques, D.K. Bass and I.R. Miller
