Traditional instruments of the trade must remain critical components of both training and real-world navigation. Here on the bridge of the USS Nimitz (CVN-68), a sextant, charts, and hard-copy recording tools sit at the ready.
Labor-saving modern electronics deliver navigational and collision-avoidance solutions more rapidly than humans can compute. Deck officers now can simply push an on/off button and collect the required data, but this is not navigating. Marine electronics process and store much more data than in the past; they provide solutions 24 hours per day, 7 days a week. In some cases they even extend human senses, because radar and the automatic radar-plotting aid (ARPA) do not need visibility. Software also facilitates cargo stowage on board ships and computes stability data, although most programs cannot do both.
Seagoing professionals are over-relying on marine electronics, which may have contributed to the collisions of the USS Fitzgerald (DDG-62) and John S. McCain (DDG-56).
Rebuild Mariners’ Skills
In both the military and commercial services, prudent mariners never rely on one source for critical data. They monitor the validity of electronic data with low-tech sources. Despite the use of gyroscopic compasses, virtually all vessels carry a magnetic compass for a directional comparison.
Both the U.S. Naval Academy and Naval Reserve Officers Training Corps have reintroduced celestial navigation to their curricula. The sun, moon, 4 navigational planets, and 57 navigational stars have been a source of positions at sea for centuries. They provide a low-tech backup to modern navigational electronics. Sight reduction tables used to solve the celestial triangle have no shelf life. Mechanical chronometers, wound each day, require no electricity to operate and provide an incorruptible source of time required in celestial computations.
By contrast, signals from navigational satellites (sky waves) are vulnerable to degradation from atmospheric conditions, and in recent years to “spoofing”—deliberate human interference. And yet a number of industries, including marine and air navigation and international banking, rely on uninterrupted signals from global-positioning system (GPS) satellites.
A growing movement is gaining strength in Washington, D.C., to restore the eLoran navigation system (ground waves) in domestic waters as a backup to GPS. This is already in place in several European countries. Receivers capable of processing signals from both GPS and eLoran compare positions to ensure accuracy.
Merchant Marine–licensed deck officers have always been required to demonstrate proficiency in collision-avoidance vector plotting. But for the past 20 years or so, direct scope plotting has not been in use; thus plotting methods have become degraded. Further aggravating this situation, Congress has ordered the Coast Guard to remove the requirement for Merchant Marine deck officers to demonstrate collision-avoidance paper plotting using a maneuvering board or radar plotting sheet. The implications of this is that all manual plotting may be discontinued.
Reinstate Direct Scope Plotting
The Navy discontinued radar plotting some time ago, but still trains on maneuvering boards. Navy and Merchant Marine officers have lost basic skills that have long been associated with professional mariners. For decades, ARPA has been the only source of collision-avoidance data on military and commercial vessels. These units can provide data for 100 or more vessels, giving the deck officer a collision assessment in a timely manner. The equipment relies on electronic sensory inputs (direction and speed). Should the sensory data be degraded by weather or human interference, erroneous collision solutions will follow. Recently the Navy standardized maneuvering-board procedures for all bridge and combat information center personnel.
Maneuvering boards and radar plotting sheets are generically known as transfer plotting techniques. This type of collision-avoidance vector analysis was found to be problematic. Under duress, many errors were made in transferring raw radar bearing and range data from the radar to the paper maneuvering board, which often resulted in erroneous solutions and near misses or, in worst case scenarios, a collision.
Maneuvering-board solutions were also known as speed triangles because the vector lengths represent the speed of the vessels in the plot, meaning the distance they travel in 60 minutes. Vectors developed using the speed triangle, which originate from the center of the maneuvering board, can take up 25–40 percent of the plotting surface. Because this makes it difficult to plot several contacts on the same plotting surface, the speed triangle was replaced by the distance triangle in the 1960s. In this new version, contacts were plotted at their locations directly on the radar scope: the direct scope method.
Using the distance triangle, multiple targets could be plotted on the same surface without overlapping. This kept the center of the scope clear, allowing detection of small contacts that might only appear at short ranges. For all these reasons, it would be a mistake to revert to the maneuvering board.
Instead, ARPA manufacturers should be required to reinstate a direct scope plotting capability. Low-tech backup for sophisticated bridge equipment is essential.
Manual plotting and other traditional methods must be the foundation of all training in navigation—and must also remain available as backup in the event of technological failures or inadequacies. Requiring deck watch officers to take a number of celestial observations should not represent a tremendous increase in workload when they are in situations of low-traffic density and non-maneuvering exercises. Anyone who cannot complete their navigational or collision-avoidance responsibilities without using a key pad or keyboard does not belong on the bridge of a ship.
Mr. Frederick holds a Coast Guard unlimited tonnage Chief Mate’s license. A longtime associate professor of Marine Transportation at SUNY Maritime College, he previously taught unlimited tonnage license courses at the Merchant Marine School at Seamen’s Church Institute and radar observer unlimited courses at the U.S. Maritime Administration radar school, both in New York. He has owned and operated U.S. Coast Guard–certified passenger vessels for 27 years.