Meredith Salmon: Tour of the Bridge, July 20, 2018

NOAA Teacher at Sea

Meredith Salmon

Aboard NOAA Ship Okeanos Explorer

July 12 – 31, 2018


Mission: Mapping Deep-Water Areas Southeast of Bermuda in Support of the Galway Statement on Atlantic Ocean Cooperation


Weather Data from the Okeanos Explorer Bridge

Latitude: 29.01°N

Longitude: 61.56°W

Air Temperature: 27.7°C

Wind Speed:  13.91 knots

Conditions: Sunny  

Depth: 5288.3 meters

Science and Technology Log 

The NOAA Corps is composed of professionals trained in engineering, earth sciences, oceanography, meteorology, fisheries science, and other related disciplines. Corps officers are responsible for operating NOAA’s ships, flying aircraft, managing research projects, conducting diving operations, and serving in leadership positions throughout NOAA. Officers are trained for effective leadership and command whether it be at sea or on land. After successfully completing NOAA’s Basic Officer Training Program, the newly trained officers report for their first two-year sea assignment aboard one of  NOAA’s 16 ships. Upon reporting aboard their ships, they will be assigned watch standing responsibilities and tasked with various collateral duties (i.e., Damage Control Officer, Imprest Officer, Navigation Officer, Morale Officer, etc.).

A typical navigational bridge watch consists of two four-hour shifts (ex. 0800-1200 and then 2000-2400) with eight hours in between to work on collateral duties. While on watch, the Officer of the Deck (OOD) is stationed on the bridge (vessel’s room from which the ship can be commanded) and accompanied by an able-bodied seaman acting as lookout or helmsman, and often times a Junior Officer of the Deck (JOOD) who is training for their OOD qualification. The OOD has earned the trust of the Command and is a direct representative of the Commanding Officer, having responsibility for the ship while the CO is not on the bridge.

The Bridge
The Bridge aboard the Okeanos Explorer

Safe navigation is the top priority. Before each change of the bridge watch, it is essential that clear, specific communication has been passed to the oncoming OOD and watchstanders to ensure the oncoming watch are aware of changes regarding navigation, traffic, weather, operations, etc.

Weather Log
Hourly position, weather, and sea conditions are logged aboard the Okeanos Explorer to show trends in meteorological conditions.
Nautical charts used to record hourly location coordinates (a.k.a. fixes)

The marine radar equipment located on the bridge of the Okeanos Explorer is crucial for carrying out safe navigation operations while underway. Radar instruments are mandatory systems for collision avoidance. The bridge watch rely on radar to successfully identify and track the precise positioning of vessels and aids to navigation out at sea. Radar uses rotating antennas that transmit and receive electromagnetic waves.

S and X Band Radars

Marine radars on the Okeanos Explorer are either X (10GHz) or S (3GHz) band frequencies. Since X-band radars have higher frequencies, they are used to generate a sharper image and resolution; whereas, the S-band radars are used for long-range identification and tracking. The X-band radars pick up weather conditions and small targets and are best used for close ranges (12 mile or less). The S-band radars are very useful in rainy or foggy weather conditions and help identify objects that located farther away (24 mile range or greater). It is especially important to use these radar systems to determine if impending vessels are in the area. The radars are equipped with an AIS (Automated Information System) feed. The AIS tool allows the user to acquire additional information about vessels in the vicinity about the size and type of the vessel, speed, course, distance of the closest point of approach (CPA) and time to CPA.

Steering Stand

The steering stand is used to direct the ship by controlling the rudder and can be put in different modes such as autopilot or manual. This piece of equipment has two gyrocompass inputs (or feeds) to provide accurate heading by determining “true north”. The gyrocompass is an instrument that relies on the use of a continuously driven gyroscope to accurately seek the direction of true (geographic) north. It functions by seeking an equilibrium direction under the combined effects of the force of gravity and the rotation of the Earth.

Steering Stand
Steering stand on the Okeanos Explorer

A magnetic compass is an instrument containing a magnetized needle that reacts to the Earth’s magnetic field by pointing to magnetic north. The magnetic compass on the Okeanos Explorer is housed in a binnacle that uses mirrors to project the compass that is located on the flying bridge. It is important that the magnetic compass is far away from electronics to prevent interference from occurring.

Magnetic Compass
Magnetic compass binnacle
Master gyrocompasses

The gyrocompass repeater (pictured below) is mounted on the bridge wings and displays directional information on the basis of electrical signals received from the master gyrocompass. Repeater compasses are designed to receive and indicate the true heading transmitted electrically from the master gyrocompass.

Repeater for gyrocompass
Repeater for gyrocompass


Electronic Chart Display and Information System, known as the ECDIS, is a computer-based navigation system that requires the use of electronic charts, sensors, and radars to offer an alternative to paper charts. ECDIS is an effective tool that allows navigators to plan and monitor routes that even include waypoints and tracklines. On this expedition, we use ECDIS along with a computer programming system known as Hypack to plan survey lines 180 nautical miles in length. Once the precise lines are created on Hypack, they are saved on a flash drive and transferred to the bridge so the person navigating the ship has the exact lines and coordinates necessary to steer the ship and obtain accurate data and overlap. ECDIS eases navigators’ workloads due to its automatic capabilities such as route planning, route monitoring, and automatic ETA.  ECDIS provides many other sophisticated navigation and safety features, including continuous data recording for later analysis. 

Propulsion controls

The propulsion controls located below the ECDIS computer monitor are known as the “sticks”. These throttles control the two fixed pitch propellers under the hull. In case of an emergency, control can be shifted to the engineers in the main control space, and the engine order telegraph (E.O.T) can be used to communicate desired speed.

ECDIS (pictured on the computer screen) is used to view lines created in Hypack


Dynamic Positioning System

Although this system is not being used on this particular cruise, the dynamic position system is designed to hold the ship in a precise position exclusively using thrusters. This system is used primarily for Conductivity, Temperature, and Depth (CTD) casts, and during Remotely Operated Vehicles (ROV) cruises when the “vehicles,” Deep Discoverer and Seirios, are in the water.

Dynamic Positioning
Dynamic Positioning (DP) System

Marine Propulsion equipment

Okeanos Explorer is equipped with bow and stern thrusters to help maneuver the vessel and hold station while in DP. In its raised position, the bow thruster is used in tunnel mode, but it can also be lowered to allow it to rotate 360 degrees for better control. The two stern thrusters are in fixed positions and work simultaneously in tunnel mode.

bridge 4


Generator Mimic

This screen displays information about the four diesel generators that are used to power the Okeanos Explorer. Three generators are online while the remaining one is used as a backup in case of emergencies. This system provides information about which generators are currently being used, the cylinder temperatures to ensure that the engines are not overheating, and alarms that indicate any potential malfunctions. The engineers abroad conduct daily maintenance to keep these engines in tip-top shape.

Generator Mimic
Generator Mimic


Global Maritime Distress and Safety System (GMDSS)

The GMDSS is a distress and radio communication system that can relay a variety of important information. This system reports weather forecasts for the navigation area approximately every six hours and includes tsunami alerts, boat reports, and ship to ship messages to ensure the safety of all vessels out at sea.

Global Maritime Distress and Safety System (GMDSS)


Personal Log

Cribbage is a card game that can be traced back to the 18th century and has been popular in the U.S. Navy since World War II. Traditionally, the game is played by two players and each player tries to form various counting combinations of cards to earn points. Score is kept by inserting pegs into holes arranged in rows on a cribbage board and the first person to reach 121 points wins. Since there is going to be a cribbage tournament aboard the Okeanos Explorer, we learned the rules of the game tonight and completed a bunch of practice rounds. We are going to make a winners and losers bracket and start the tournament this week!

Cribbage champions
Practicing Cribbage!


Did You Know?

Compasses are affected by nearby ferrous materials or electromagnetic fields. When they are placed on the vessels that have high metal contents, they have to be corrected and calibrated. That is done with the use of built-in magnets fitted within the case of the compass.



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