meras.

Control console - Topside control of all ROV functions and peripheral
equipment (for example, sonar, tracking, and manipulator functions).

Umbilical - Connects ROV to control console. Provides power, data
transfer, and strength member. Usually copper wire or combination of
copper wire and fiber optics.

Thrusters (or ailerons on towed vehicles) - Allows pilot to fly the vehicle to
its destination while avoiding obstacles.

Floatation - More floatation that's built into the vehicle increases its
payload capacity. Usually syntactic foam, a sealed air chamber, or a
combination of both are used. Only larger ROVs have variable floatation
capabilities.
Principal Applications - Biology, Geology, Chemistry

Video/photographic documentation - Most common and easiest. Provides
visual record for proof or later analysis in lab.

Site or structure survey - General information, comparison data, structural
arrangement or condition.

Light instrumentation deployment/retrieval - Makes ROV more than just a
"swimming eyeball." Provides data collection capabilities.

Sample collection - Collect objects (data) by discrete sampling of
sediment, water, plankton, algae, etc.

Search and recovery - Most difficult. If you can find it, can you attach a line
to it?

Pre-dive (scuba or submersible) survey - Save limited scuba dive time and
time on expensive submersible operations.

Test platform for new equipment - Test concept design and function of
equipment, and adds to arsenal of tools for data collection capabilities.

Education - Outreach, knowledge, and information dissemination.

Behavioral monitoring - Mating aggregations, survival techniques, feeding
habits, etc. Advantages of using ROVs for undersea research:

Portability - Fly or land transit anywhere in the world.

Minimal support personnel - Requires only one technician/pilot and usually
one other person (staff or science crew) for deck operations.

Deployable from "vessel of opportunity" - Just about any size vessel with
AC power will work. Smaller vessels are often better since they're more
maneuverable than larger vessels. The ROV has even been deployed
from docks and even sea ice.

Highly maneuverable - Up, down, forward, backward, crab to either side or
combinations.

Bottom time limited only by operator endurance - Center policy limits dives
to less than four hours due to pilot fatigue. Piloting requires total and
continuous concentration. Having more than one pilot to work in shifts is
highly advantageous.

Can operate in free-swimming or "downweight" configuration - Variations
on both of these configurations provide a range of deployment techniques.
Operational requirements determine which technique is utilized (i.e. free-
swimming for maximum mobility or when the potential for entanglement is
high, and downweight in high currents, deep deployments, or transect
work.)
Disadvantages:

High maintenance - Seawater and electronics do not mix! Mechanical
maintenance is usually easy and quick to repair. However, electronic
maintenance requires extensive troubleshooting and electronics
knowledge. Spare printed circuit boards are kept on hand to facilitate
faster repair and preclude cancellation of missions.

Affected by current/sea state - Currents deter mobility. Current acts more
on the umbilical than the ROV itself. The downweight deployment method
is frequently used to counteract the effects of current on the umbilical. The
ROV is severely limited in currents exceeding two knots. Sea state mainly
affects deployment and recovery of the vehicle. In heavy seas, this is the
most dangerous activity for the ROV and deck personnel. Once away from
the vessel or in deeper water, the ROV is relatively safe, however, sea
state also affects the maneuverability of the support vessel.

Entanglement - Entanglement is the leading cause of vehicle loss. Not
surprisingly, it is usually the umbilical, not the ROV that becomes
entrapped or snagged. This is especially true with umbilicals that sink and
drag across the bottom. Newer umbilicals often float directly above the
ROV. A well-trained deck person is a great tether management system
and can reduce the risk of entanglement. The ROV pilot needs to be
continuously aware of potential hangs and how the umbilical is reacting to
operational and natural influences.
Minimal payload capacity/support - The center's Super Phantom can
support 32 pound of payload (in water) before floatation must be added.
The Phantom 300 can support 4 pounds of weight. Payload weight must
be distributed evenly in order to maintain the vehicle's horizontal trim.
Additionally, floatation is generally bulky and creates more drag. A general
rules of thumb is that the weight goes on the bottom of the vehicle and the
floatation on top. Plus, it's imperative to only use floatation that will not
change with depth/pressure.

Scaling/measurement from two-dimensional TV screen - "How big is
that?" is probably the most common question asked on ROV missions.
Objects look bigger or closer underwater. Different angle of view from
camera to camera make objects appear to be different sizes, and objects
appear larger as they get closer to the camera. Ancillary equipment, such
as stereo cameras, parallel laser beams (which introduce a scale into the
picture), and computerized scaling equipment provide quantitative
measurement capabilities.

Lack of peripheral vision - Vision through a camera lens is finite, often
compared to having blinders on. Oftentimes, you can be right next to the
object that you're looking for and not "see" it. Pilots combat this by staying
up off the bottom and looking far ahead to get the biggest panoramic view.
Also, pilots can sweep the vehicle or camera from side to side to see
more. Water clarity, ambient light, and the light sensitivity of the camera
are also contributing factors.