Page images

To improve the user's understanding of the alphanumeric position information in Table I, a graphical analog display will show the vessel's attitude and cross-track distance. Perhaps a line representing the desired track and a simple shape representing the vessel would be used as illustrated in Figure 8. This display could contain electro-mechanical devices, or could be presented together with the Table I information on a CRT.

[blocks in formation]

A paper or magnetic tape device will provide a periodic recording, for postmission analysis, of the parameters in Table II. Data will be recorded upon operator command or automatically at an operator-selected interval.


Loran-C Hyperbolic time differences.

Distance to turn.
Cross-track distance.
Quality factor.

Extended graphics

User Equipment II may include an extended graphics capability to provide a real-time analog CRT display of the vessel's position superimposed on a pre-stored background. Background features include the channel edges (showing variations in channel width), navigational aids (buoys, lights), prominent geographic objects (rocks, trees, structures, (and the desired trackline with turning points. Look-ahead information is displayed as a scaled leader extending from the reference point on the vessel. Variable scale factors will allow the simultaneous display of up to ten miles of channel. System demonstration

Verification and demonstration of User Equipment II will closely follow that of User Equipment I (COGLAD). After checkout aboard Coast Guard vessels, the system will undergo a demonstration and data collection phase aboard one or more lake carriers.

69-088 0 - 76 - 4


The user equipment/mini-chain demonstration phase is scheduled to terminate on 1 June, 1976. The Coast Guard Research and Development Center will prepare a comprehensive final report for the project including a summary of pertinent information gathered during the demonstration phase, recommendations for system improvements, and suggested expanded applications for similar Loran-C-based systems.


Visual aids for the COGLAD equipment were supplied by Mr. R. B. Hester and Mr. C. R. Edwards of the Applied Physics Laboratory. The St. Marys River chart of Figure 1 was provided by Mr. D. Westheiser of the Detroit Districts, Army Corps of Engineers.


1. R. C. Moore, C. R. Edwards, R. K. Burek, and G. D. Wagner, "COGLAD: A Coast Guard Loran-C Assist Device,” The Johns Hopkins University Applied Physics Laboratory, Report CP 206, March, 1973. Available from NTIS, Springfield, VA 22151 as AD-765 935.

2. J. Jepsky and L. Ervin, “A Precise All Weather Marine Navigation System,” presented at the 30th Annual Meeting, Institute of Navigation, June 27, 1974.

3. Proposed Direction For Analysis of Aids to Navigation in Restricted Waters.

[APPENDIX G] In recent years tools have been developed through technological advances that enable engineers to refine the analysis of vessel maneuverability in restricted waters. The purpose of this article is to inform Coast Guard personnel of the availability of these new analysis techniques and propose a long-term direction for the improvement of the Aids-to-Navigation (A/N) system.

The Aids to Navigation Manual (CG-222-I) states the objective of the A/N system as “to promote safe and economical movement on the navigable waters of the United States

In order to accomplish this objective properly in a professional manner one must take a look at the entire system that affects vesel maneuverability (see Figure 1). Notice that the system is centered around the pilot's ability. To attempt to optomize each of the subsystems (e.g. vessel design, visual aids, electronic aids) is not necessarily optomizing the total system. The total system is to be used by a human being. Therefore, it must be tailored to this human being's ability. Certainly we have been attempting to optimize each of the sub-systems with the ship handler's ability in mind. Today, tools exist that allow engineers to give this total system concept more than cursory analysis. Partial computerized vessel maneuvering simulators are these primary tools (see Figure 2). A partial simulator is one that leaves the human operator in the system and models the environment around him. It is more costly than a complete simulator but is more accurate and realistic since it is extremely difficult to model the human operator by a transfer function? The ability of human beings to control automobiles, airplanes, submarines, and space vehicles were all refined through the use of simulators.3.3 The human engineering element of vessel maneuverability in restricted waters is seriously neglected.

One key element of tailoring the system to the pilot is the presentation of the harbor to the man on the bridge. Where should the navigational aids be placed? Where should the channel be dredged? What type and amount of information should be transmitted to the pilot? How and at what rate should

this information be presented ? Is a real-time environmental bridge display required for a particular harbor to allow the pilot to anticipate more and react less to changing current and wind ? * What are the pilot's stress levels during the transit of a particular channel ? 5

[blocks in formation]

Maneuvering simulators are a means of testing various presentations of the harbor to the man on the bridge so that the optimum aid system can be designed. They are also used to improve the maneuvering characteristics of vessels and vessel control systems. In addition these man-machine systems are an aid in training new shiphandlers, or old shiphandlers on new ships.

Should the Coast Guard use this more technical approach to the A/N problem? Is it cost-beneficial? Other countries (e.g. Netherlands and Sweden) are already using this approach.",8 The Coast Guard is presently implementing the buoy-to-structures replacement program originally recommended in the 1970 Booze-Allen report. Should not the location and even the existence of the more immovable structures be examined on appropriate technical standards developed by a partial simulator? Should not each Vessel Traffic System have technical standards based on appropriate human engineering studies of vessel controllability? Can we afford not to determine the answers to the above and other related questions?

The Sperry Rand corporation is presently under contract from the U.S. Maritime Administration to build a partial maneuvering simulator at King's Point, New York. Commandant (G-DST) and (G-MMT) are involved with planning the Office of Merchant Marine Safety's desired uses. The author feels

that the Coast Guard, in an effort to improve the A/N system, should investigate a complete system approach optimized around the shiphandler, with particular emphasis on the presentation of the harbor to the man on the bridge. RADM A.H. Siemens, Chief, Office of Research & Development, has also proposed testing A/N projects thru modeling and emphasized the necessity to base the A/N system on “logical, technical standards." 9 The author would like to reiterate the importance of tailoring any such modeling techniques or A/N technical standards to the human operator's ability.

It is recommended that the Coast Guard investigate adopting this human engineering system approach to the A/N problem at the earliest opportunity. The United States Coast Guard, with access to the world's most advanced technology, should continue to be a leader in the practical management of this technology to derive solutions for our marine problems.


1. Gynther, James W., Analytical Prediction of Vessel Maneuverability in

Narragansett Bay, Master's Thesis in Ocean Engineering, University of

Rhode Island, 1974. 2. Meister, David and Rabindeau, Gerald F., Human Factors Evaluation in

Systems Development, New York: John Wiley and Son, Inc., 1965. 3. Parsons, Henry M., Man-Machine System Experiments, Baltimore: John

Hopkins Press, 1972. 4. Van Dixhorn, ir. L. A. and Hooft, Dr. J. P., Feasibility and Profit of Navi

gation Information and Navigational Aids Offshore, prepared at Netherlands

Ship Model Basin, 1973. 5. Hooft, J. P., Criteria for the Maneuverability of Ships Steered by Pilots,

prepared at Netherlands Ship Model Basin, 1973. 6. Hooft, J. P. and Oldenkamp, I., Construction, Operation and Capabilities

of the NSMB Ship Maneuvering Simulator, prepared at Netherlands Ship

Model Basin, 1971. 7. Hooft, J. P., Private Interview held with LT J. W. Gynther, USCG at

Netherlands Ship Model Basin, Wageningen, Netherlands, October 2, 1973. 8. Norrbin, N. H., Private Interview held with LT J. W. Gynther, USCG, at

Swedish State Experimental Tank, Goteborg, Sweden, October 5, 1973. 9. Siemens, A. H., RADM USCG, remarks to the ATON Management Training Course, Governors Island, New York, on 1 April 1974.



(By J. P. Hooft, V. F. Keith, and J. D. Porricelli)


When considering the controllability of ships there is much within the literature which is devoted to the maneuverability of the ship. In this sense, the maneuverability of the ship refers to the inherent hydronamic characteristics of the ship to be controlled. This paper concerns itself with the human factors which, together with these inherent qualities of the ship, dictate the overall controllability of the ship. A ship is considered to be controllable when her inherent maneuvering characteristics are such that a range of responsible mariners are able to limit the deviations from an intended maneuver within an acceptable range over a series of trials.

It will be obvious that the executed maneuver shown in Fig. 1, deviates from the intended maneuver (shown by the solid trackline) to the extent that

the ship has touched the channel bank. This loss of control in this situation was not necessarily caused by inadequate ship maneuvering characteristics. The loss of controllability can equally as well be attributed to an ill-chosen channel configuration in the harbor, to unacceptable environmental circumstances, such as wind or current, or even to the inexperience or inability of the mariner in controlling the ship.

The literature leads one to the preliminary conclusion that the control of large ships is somewhat more complex than the control of small ships, primarily due to the difference in inertia and, therefore, in the response of the ship relative to human reactions in a particular situation. It is for this reason that only recently, with the introduction of large ships, has attention been focused on the maneuverability of ships. Prior to the onset of the economics of scale and the proliferation of very large bulk carriers, the maneuverability of their smaller counterparts, even in restricted and congested areas, had been of little interest.

This paper considers only these situations where a ship maneuvers within a restricted waterway, as for example, at the entranceway to a harbor or when transiting a congested channel. In these situations the physiological aspects of men play an important role. Furthermore, their psychological characteristics such as responsibility, mental stress and instinct, combined with their ability to react under such circumstances, play an equally important role.

The results of research on human behavior can be used to optimize existing situations such as the task of a pilot or a captain in commanding a ship, limiting traffic density of a harbor, or the operation of navigational aids. An improvement of an existing situation may not only lead to a more cost effective operation, but may also lead to a higher level of safety in terms of accident mitigation.


It should be stated at the outset that ships are always controlled by men. Even when the ship is automatically controlled such as through an autopilot or even a computer, the input is always made by men. On the other hand, the navigation of ships by men has always been accomplished with the use of mechanical aids such as a magnetic compass. This introductory remark is made to demonstrate that the idea of automation affects neither the human responsibility nor man's ability to control a ship. It may, however, improve the controllability of the ship itself. When trying to analyze human behavior one should recall a quote of C. E. Noble: "Human behavior is predictable. This inductive generalization is as widely accepted by psychologists as it is doubted by laymen” (1). Starting from this psychological hypotheses, one may describe human behavior.

Human responses are performed on two levels. The first level is decisive actions. The responses at this level will result in commands and actions as to the manner in which a desired maneuver will be executed. The second level of human responses can be qualified by the term,"track-keeping”, in which the human operator has a controlling function, which is analogous to an automatic servo mechanism.

From research which was conducted by a. noted psychologist, Poulton, it now appears that many systems analysts and engineers are attempting to describe the human function by a mathematical expression (3). The results of this type of research answer the question "how" rather than “why" do men act in a given way. At the moment, this type of engineering research is the only promising method which would be useful for optimization studies (assuming that the man's description is constant throughout the desired operation).

« PreviousContinue »