Page 592 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

they offer many beneficial trade-offs (i.e., smaller footprint, lower power requirements, more mobile, capable of getting into smaller areas).
21.4.4 Port security needs
For the purposes of this manual, underwater port security tasks fall under two broad categories:
1. Search and identification of underwater targets or areas of interest. Examples may be limiting an inspection to a vessel’s running gear or searching a particular location based on intelligence.
2. Search and inspection of general areas of interest for potential threats within the security area. Examples may be conducting a search/inspection of all the pier pilings within a specified zone prior to the arrival of a high-value vessel.
Search and identification of underwater targets is accomplished through four basic steps:
1. Research to define the area of interest
2. Wide area search with instruments and sensors
3. Narrow area search with slow-speed instruments
4. Final identification, visual discrimination, and disposition—that is, diver or remote camera
propelled to the inspection site.
ROV intervention as a productive and cost-effective means of final identification, discrimina-
tion, and disposition is analyzed in this manual. Refer to Section 21.3.4 for a more detailed discus- sion of the previous four steps.
21.4.5 Underwater environment of ports
The underwater environments of ports within the United States (and the remainder of the world) vary in temperature, water clarity, operating currents, and vessel traffic. The environment in Seattle, WA (cold deep water, good visibility, moderate currents, and moderate vessel traffic), var- ies significantly from the Port of New Orleans (warm deep water on the Mississippi River, poor visibility, high currents, and moderate vessel traffic), the Port of Galveston (warm shallow water, poor visibility, low currents, and low vessel traffic), and New York Harbor (cold shallow water, poor visibility, high currents, high vessel traffic, medical waste, etc.).
Accordingly, the environmental factors that determine the difficulty of completing an underwa- ter port security task with an ROV system follow:
• Currents determine the ability of the submersible to successfully swim to, and station-keep near, a fixed object while countering these currents.
• Water depth determines the offset from the deployment (water insertion) point to the bottom for bottom clearance searches as well as proximity of bottom to vessels/moorings/ anchors/piers.
• Vessel traffic determines the relative security of the inspection operation (a more secure location produces an easier inspection task).
• Water temperature determines the resources and expertise necessary for a dive team to enter that environment along with loiter time.
21.4 Homeland security 591