Working underwater presents several challenges, and most call for expensive cures.
One way to handle many underwater tasks, including surveying, gathering data, and checking water quality, is to use an Iver-2, the next-generation underwater vehicle from OceanServer Technology Inc., Fall River, Mass. (ocean-server.com).
The autonomous sub measures almost 49 in. long, weighs 42.5 lb, and can submerge to depths of 200 ft. It uses lithium-ion batteries for over 550 W-hr of power, enough to let it travel up to 8 hr at 3 knots. The batteries can be recharged up to 300 times. The vehicle travels between 1 and 4 knots, but will go 6 knots with an optional and larger motor.
Users program the sub using standard georeferenced charts from NOAA, USGS, or satellite images. Missions are set up on a PC by placing waypoints and establishing parameters for speed, depth, and behavior on each leg of the mission. Behaviors can include spiral dives or rapidly oscillating between two depths. Programs are output as ASCII files sent via WiFi to Iver 2. The sub navigates by GPS when on the surface and by dead reckoning when submerged.
Several onboard sensors track vehicle depth and total depth. It also carries a low-light camera and has room for more sensors, For control, it carries a single-board computer with low-power X86 processor and a large memory. Besides sampling water quality and charting or surveying, the sub can inspect piers, vessels, and port facilities, look for mines, or serve security duty for harbors, dams, and locks.