The Pisces V submersible underwater about to dive. Click image for larger view.
The Pisces V and Pisces IV
The Pisces V and Pisces IV are three-person, battery-powered, submersibles with a maximum operating depth of 2000 m (6,280 ft). These vehicles allow scientists to observe the deep sea through multiple view ports, video records, instrument placement, sample collecting, and environmental monitoring. The submersibles are launched and recovered with a specialized A-frame on the aft deck of their primary support vessel the R/V Ka‘imikai-o-Kanaloa. A typical dive lasts from 6 to 10 hours “hatch to hatch.” The submersibles are launched and recovered during daylight hours only and in the evenings they are serviced on board their support vessel in the submersible hangar.
HURL has the unique advantage of having access to two deep-diving submersibles at the same time. This allows one submersible to conduct science dives while the other remains in ‘ready’ status in case of an emergency. For example, if the working sub were to get stuck at the bottom of the ocean or trapped in abandoned fishing nets, the second sub would be loaded onto a Coast Guard cutter and rushed to the site where could work to free the first sub. While a typical dive lasts for less than 10 hours, both submersibles have emergency life support for three people to remain onboard for 5 days. Alternatively, some research projects might benefit from the use of two submersibles at the same time.
The Pisces IV being launched from its support vessel the R/V Ka‘imikai-o-Kanaloa. Click image for larger view.
Both of HURL’s Pisces submersibles were built by International Hydrodynamics of Vancouver in British Columbia and were classed by the American Bureau of Shipping. Each submersible weighs 13 tons and has a payload of 600 pounds. The personnel sphere of each sub is 7 feet in diameter and is made of HY 100 steel, The sphere can maintain 1 atmosphere of pressure at depths of at least 6,200 feet. This operating depth is ideal for the waters around the Hawaiian Islands where Pisces IV and Pisces V conduct the vast majority of their operations. Common dives sites include the undersea volcano Lo‘ihi (southeast of the Big Island of Hawai‘i), submerged banks in the main Hawaiian Islands, and banks and seamounts in the Northwestern Hawaiian Islands. Both submarines have two side-mounted reversible thrusters which allows the pilot to maneuver through a dive site at speeds up to 2 knots.
The primary data that comes from the submersible dives are videos. Each sub is equipped with three digital cameras. At least one of the cameras is on at all times during a dive. Oservers in the submarine can choose to turn on one or both of the other two cameras to obtain additional imagery as they see fit. One camera on each subs is a low-light black and white camera. This special camera allows deep (up to about 1000 feet) environments to be evaluated under natural light conditions. Colors look dramatically different and fish behave differently once the sub’s glaring lights have been turned off. Each year HURL scientists find new species of fish or invertebrates in the relatively unexplored depths around the Hawaiian Islands.
The Pisces V being launched from its support vessel R/V Ka‘imikai-o-Kanaloa. Click image for larger view.
In addition to it's video capabilities, both submersibles have two manipulator arms each – the right one a bit more dextrous than the left. A skilled pilot can use the arms to collect samples,biological or geological, and store them in a mounted sample basket. In addition to collecting samples, the arms can be used for many other tasks including the placement of small temperature recorders into hydrothermal vents, or to gently push the sub backwards when the pilot wants to avoid stirring up sediments with the thrusters.
The Web team gratefully acknowledges this contribution by Rachel Shackelford, the Data Department Manager of the Hawai‘i Undersea Research Laboratory.
