ROV Operation from a Small Boat

Remotely operated vehicles (ROVs) are useful tools for aquatic research, but are underutilized because of the high operational costs and limited versatility of older models. Scientifically useful ROVs were originally very expensive to purchase or lease, and costly to operate with limited models available. With an increase in the number of models available and lower operating costs, the use of ROVs in science is steadily increasing. However, scientists may be reluctant to use this technology because of past budgetary and operational constraints, or are unaware of the lower-priced models that are now available. There are a number of ROVs that are relatively inexpensive and can be operated without specialized teams and platforms. We describe how to greatly reduce ROV operational costs and increase versatility by operating the ROV with two to three people from a small boat without hydraulics and in limited space. This combination can be safely used in a variety of weather conditions. For this purpose, any recreationally used personal boat is considered a small boat. We used a Phantom XTL ROV1 and boats (without cabins) ranging from 16 to 24 feet long; both were chosen for low price and light weight, and had adequate features and design for safe and reliable nearshore scientific research. tations of depth, current and wind speeds and sea states that will keep surveys nearshore in less intense weather and sea conditions. Beginning in the mid-1990s, scientists at the NOAA Fisheries Auke Bay Laboratory needed to survey a plethora of nearshore habitats throughout southeastern Alaska to document biota from water depths of 250 ft to shore. Research objectives included determining the distribution, habitat, and behavior of rockfishes (Sebastes spp.), assessing the availability of nearshore prey to sea lions at two southeastern Alaska haulouts, and documenting nekton found in numerous nearshore habitats for Essential Fish Habitat (EFH) studies. The surveys needed to be conducted at frequent intervals throughout the year for several years in remote bays, coves, and canals close to shore in shallow (<250 ft depth) rocky or vegetated areas. Most of these areas could not be surveyed using a larger boat or a larger ROV. Traditional and modern sampling techniques using fishing, drop cameras, and hydroacoustics addressed only some of the survey needs. Fishing methods such as trawling or seining were labor intensive, expensive, destructive, and did not allow for studying ethology or habitats on a fine scale. Drop cameras were useful for studying behavior at a variety of depths and at a fine scale, but did not have enough control. Hydroacoustics did not give a fine enough habitat scale, made fish identification difficult, and is unable to survey the benthic biota. With the scientific use of ROVs on the rise (Auster, 1992, 1997) and their apparent usefulness and cost effectiveness for our aquatic research, we decided to purchase a small ROV for about $60,000. The ROV we decided on was the Phantom XTL from Deep Ocean Engineering; this unit is 42 in long, 18 in high, 21 in wide, and weighs 100 lbs. The ROV has 41 lbs of thrust, a speed of 2 knots, a maximum operating depth of 1000 ft, two 150-watt halogen adjustable lights, two lasers 10 cm apart, and a high resolution, color, video camera with zoom and tilt. The Phantom XTL can be easily carried, deployed, and retrieved by one to two people without using any hydraulics. This ROV is not as small as the MiniRover MK II or Phantom S2 (Norcross and Mueter, 1999) which weigh 65 lbs, and not as large as the Phantom HD2 (Fox et al., 2000) or Phantom DS4 (Hardin et al., 1992) which weigh 220 lbs. All of these ROVs have been proven as useful scientific machines. The smaller machines were a little under-powered for our R I N T R O D U C T I O N emotely operated vehicles (ROVs) have proven to be useful aquatic research tools. Most ROVs used for scientific research are large, such as ROPOS (Shepard and Juniper, 1997) and ISE Hysub ATP 40 used by MBARI (Robison, 1992). These large and powerful machines are expensive to lease and more expensive to operate. They require trained operators and special platforms that use cranes and hydraulics to deploy and retrieve the ROV (Fox et al., 2000). Smaller ROVs have been found to be effective research tools, are 40% cheaper to lease, use a charter vessel that is 70% cheaper (Hardin et al., 1992), and are simpler to deploy, operate, and retrieve. Use of a small ROV has been proven advantageous (Norcross and Mueter, 1999) by giving the scientist more insight into smallscale habitat use (Auster, 1991), spatial distribution (Parker, 1994), and ethology (Spanier, 1994). Small ROVs can be operated with quicker response time and in more remote locations (Donaldson and Trusting, 1997). Small ROVs also allow close side-byside interaction between the ROV pilot and scientist, who is offered better interaction with the environment for more accurate and efficient scientific study (Robison, 1992). Operational costs for small ROVs could remain high due to the continued use of large charter vessels with specialized teams and platforms. Use of a small boat < 24 feet long would eliminate this cost. The drawbacks to using small ROVs in small boats are the limiFootnotes 1 Reference to trade names does not imply endorsement by the National Marine Fisheries