Page 259 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

248 CHAPTER 9 LARS and TMS
• Always follow your tether back out from the work site with the submersible to the insertion point while pulling the tether slowly back with as little free tether behind the vehicle as possible.
• A clean and organized workplace is a safe and productive workplace.
• Tether turns are introduced when the submersible is turned from its original heading.
Minimizing the number of tether turns while operating will enhance maneuvering. Remove all
turns before submersible recovery.
• Be observant of obstacles located near the submersible that have the potential to snag the
vehicle or the tether.
• If the vehicle is at the end of its tether, there may not be enough slack to allow an easy turn-
around to follow the tether out. In this case, reverse direction to generate slack, and turn the
vehicle around to manage the tether.
• Avoid weaving in and around fixed objects, such as baffles, pipes, pilings, rocks, and anchors.
When operating in possibly fouled areas, it is advisable to remain on the surface until the
vehicle is approximately above the work site and then dive.
• Attention must be paid to objects standing vertically or horizontally in the water column, such
as anchor chains, pilings, lines, pipes, and cables. The vehicle’s tether can easily become
entangled. In currents, approach such items from the downstream side.
• If operating from an anchored ship, avoid working on the upstream side of the anchor.
• When operating in an area containing obstructions or obstacles that could snag or foul the
tether, the operator should endeavor to remember the route taken to get to any one position. Not only will this information be helpful on the return trip, it will be valuable in the event the tether does become snagged!
• If the tether does become entangled, do not pull the tether to free it. The best course of action will present itself after careful and cautious consideration of the alternatives. During a recent operation, while performing a penetration of a wrecked aircraft at 425 ft (130 m) of seawater, the submersible became entangled in the wreck a total of 16 times during an 8-hour period. Tether snags happen as a normal course of operations. Plan for them and take positive precautions to manage the tether lay throughout the work site.