Proposed Shipboard Maneuvering Data

Alexander Landsburg, James C. Card, Haruzo Eda, Harry C. von Breitenfeld and Thomas Knierim*

Resolution A. 160 of the Inter- Governmental Maritime Consultative Organization (IMCO) recommends to governments that they ensure that the master and officers of commercial ships have readily available on the bridge all necessary data concerning the maneuvering capabilities of the ship and stopping distances under various conditions of draft and speed.

The concepts for providing this information on a ship's maneuvering capabilities have been developed by SNAME T&R Panel H-10 (Controllability). While the concepts presented have already been exposed to a broad segment of the marine industry and have received favorable reaction, the Panel developed this paper to provide the opportunity for all interested parties to review the concepts. A widespread consensus on these standardized formats is desirable so that future national and international regulations will be useful and consistent.

A later IMCO recommendation, Resolution A. 209, specified that a maneuvering booklet be supplied to all ships and detailed the data to be presented. The U.S. Coast Guard implemented these ideas in 1975, requiring maneuvering information to be mounted on a bulkhead on the bridge of all ships entering U.S. waters. This attempt to provide the master and pilot with useful maneuvering information was met with industry concern over the utility of the information.

SNAME Panel H-10 is concerned with the whole of vessel controllability from ship design to underway navigation. While there has been much analysis of ship capabilities, little emphasis has been put on development of this analysis and trial information for practical use by the master. The Panel decided to examine the types of maneuvering information that would be most useful, and to determine the best methods for obtaining and presenting it.

The Panel began the project in 1976 by requesting comments on the needs for information from 135 organizations in the marine industry. Of the one-third that responded, nearly all strongly endorsed the need for such information and sent comments and suggestions.

The Panel analyzed the responses and drafted proposed informational formats to accomplish the indicated needs. These proposals were then sent back to those who had responded to the first request. The information formats presented in this paper are the consolidation of those comments.

The emphasis during development has been to step back and determine what data really should be presented and in what form it should be. The formats generated were not limited to just meeting current regulations and in some cases they don't even comply.

Basic assumptions are that the concepts and presentations should be useful, standardized, lasting (but adaptable to technological changes), simple, inexpensive and complete.

Needs For Information Ship's officers and pilots have traditionally acquired shiphandling skills on-the-job under the tutelage of experienced shiphandlers.

While learning the skill took time, the apprentice had plenty of opportunity for experience as most ships possessed similar handling characteristics. In the 1960s the situation changed dramatically as ships of increasing size and speed were built. Ship forms and their general characteristics have also undergone radical changes to the noint where maneuvering capabilities are quite different from one vessel to the next.

Specific objectives of maneuvering information should depend directly on personnel needs and abilities to use the data supplied.

The following questions must be considered: 1. Who needs the maneuvering information and what benefits can be expected in terms of increased safety or effectiveness of vessel operations?

2. What information is needed by the pilot, the master and deck officers?

3. What are the different users' information priorities?

4. How can information be used in the process of ship handling?

5. What is the best way to make this information available to different users, and what must be available f o r "quick reference"?

Where will the information be needed, i.e., in the person's pocket, posted at some convenient spot, laying on the table close at hand, in a cabin for study, in the chartroom bookcase, etc.?

6. What information is "vital" and what is only "interesting"?

7. How can the information be developed? (Tests, calculations, etc.) 8. What degree of accuracy is required ?

9. What cost is reasonable per ship class?

Shipboard maneuvering information is primarily for use by the conning officer. It should help him in guiding the ship in the following general situations: Open seas, Port approach/departure, Berthing and anchoring, and Systems failure.

Ship handling, however, is truly an art where the "feel of the wheel" or feeling of oneness with the ship is all important. Measurement of the forces under one's control is nearly as difficult as those not under control. Often this control must be within the confiines of channels, rocks, reefs, and shoals which constitute an ever-present danger and require expertise in the art of ship handling, backed by an intimate knowledge of the pilotage area and the peculiarities of the particular vessel.

Proposed Formats The Panel concluded that the concept of three standardized formats is the best way to provide useful information. The formats are: 1. Pilot Information Card (Figure 1)—A small pocket card (3y2 inches by 5Y> inches) that would contain ship's maneuvering information of prime importance to the pilot. It provides a minimum of needed information noting unusual vessel particulars. It would be filled out with any additional pertinent data and given to each pilot as he boards.

2. Posted Bridge Diagram—A compact diagram in two parts (each 11 inches by 14 inches) mounted in a conspicuous and convenient place on the bridge. It would contain principal maneuvering information of a permanent nature for ready reference by both pilots and shipboard personnel.

3. Shipboard Maneuvering Booklet—A detailed manual containing information and instruction on ship's maneuvering capabilities.

Although it would be kept available on the bridge ready for quick reference, it is intended primarily for longer term study.

The use of a looseleaf binder would provide a convenient, easily referenced catalogue of useful maneuvering information. A section for added notes by the master on the vessel's capabilities would also be helpful. Form fillins could be provided for pertinent information such as best headings for a Williamson turn.

Such standardization will also make the booklet useful to pilots for augmenting the brief, readily available information provided on the pilot card and bridge diagram.

The standardized design of the pilot information card and posted bridge diagram were drawn from some presentations currently in use. The general design of the bridge format was taken from a standardized d i a g r am developed by the Oil Companies International Marine Forum (OCIMF).

The OCIMF form satisfied both the IMCO resolution and present U.S. Coast Guard regulations.

L o o k i n g to the future, Panel H-10's proposed format goes beyond present requirements in some areas, while omitting some specifics in other areas (for this reason the proposed diagram cannot be used to satisfy the present Coast Guard requirements).

Data Acquisition Costs of providing shipboard maneuvering data must be considered and balanced with the benefits to be achieved. Even with the current state-of-the-art of analytical ship model testing and full-scale trials analysis, it is not possible to provide information that will precisely say what trajectory will occur under all conditions.

Indeed, ship handling margins will always be n e c e s s a ry since even a small current has a tremendous effect which overshadows even moderate prediction inaccuracies. It is possible to inexpensively provide a reasonably accurate "relative" measure of a vessel's inherent maneuvering capabilities. Consistency of the data in showing relative capabilities between vessels is re required, however, if the information is to be valuable.

Development of the maneuvering information for the proposed formats would usually be the result of combining a number of techniques. A series of full-scale trials will normally be available on the first of a ship class. In some instances ship maneuvering model tests will have been performed on the design, often resulting in a mathematical model for the prediction of ship maneuvers.

Where such information is not available, computer-aided estimates using standardized series or similar ship test results could be used to develop the data presented in the pilot information card and the posted bridge diagram.

Data development costs will vary according to data sources and unusual characteristics of the ship involved. Normal analysis and preparation costs range from $400 to $1,200 per ship for either the single posted bridge diagram or 1,000 copies of the pilot information card.

The Shipboard Maneuvering Booklet is proposed primarily as a standardized outline into which the operator would provide infor- mation in the amount and the level of detail considered useful.

Costs are thus difficult to project.

The booklet should, however, provide a convenient format to report available information on the ship and should not be considered an expensive item.

Conclusions Information on a vessel's maneuvering capabilities is needed by masters, mates and pilots to minimize the increasingly severe consequences of vessel accidents.

Panel H-10 (Controllability) of SNAME has developed concepts for the standard presentation of this information. These concepts are described in this paper to develop a consensus on requirements and to set presentation format standards.

The major requirement is to develop standardized formats f or data presentation from which pilots and mariners can quickly learn about a ship's maneuvering characteristics, and compare one ship to another.

Absolute accuracy of the data is less important than its relative indication of how well the ship can be expected to maneuver compared to how well other vessels have performed. The effects of current, wind and other factors are often very s i g n i f i c a n t and overshadow the inaccuracies in maneuvering data prediction.

Standardized presentations of data should be both lasting and a d a p t a b l e to technological improvements while remaining inexpensive to develop. Recent shallow- water ship trials and model tests, for instance, provide the basis for relatively accurate estimation of shallow-water behavior.

Such predictions should be included for the use of the mariner.

I n f o r m a t i o n to be presented must be carefully selected to ensure that the mariner is not overloaded with data.

Other stories from July 15, 1980 issue


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