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without a proper exchange of whistle signals.

Additionally, this collision serves to emphasize an effect of excessive speed. In a meeting situation, with a consequently high relative speed, the time available for maneuvering to avoid collision is so drastically reduced that there is insufficient time left to evaluate and resolve confusing situations. Consequently, early reductions in speed are absolutely necessary when there is any uncertainty over the other ship's intentions. Reductions in speed will provide the additional time to clarify a situation,

The collision also emphasizes the necessity for a proper exchange of signals. An exchange of signals is mandatory, under Section 80.3, Pilot Rules for Inland Waters, for vessels in sight of each other when passing or meeting at a distance within half a mile. This is a duty all too frequently ignored. The signal should be initiated as early as practicable, and the reply should be given promptly. If the initiating ship fails to receive a reply, it must sound the danger signal (Sec. 80.1, Pilot Rules for Inland Waters), prior to sounding a second signal.

As a result of this casualty, two men were killed and two officers injured aboard Ship B and the ship, valued at $225,000, was a total loss. Ten crewmembers were injured aboard Ship A and the ship received damages estimated at $415,000.

CASE 2 The principals in this case were a U.S. passenger steamship (Ship A) of 23,754 gross tons and a Norwegian motor tanker (Ship B) of 12,228 gross tons. The collision occurred about 5 miles southeastward of Ambrose Lightship. At the time of the casualty, there was a slight northeasterly sea with a short easterly swell; the wind northeast, force 3; a dense fog, with visibility less than one-quarter mile.

SHIP A Ship A departed Newport New Va., at 1334 EST, 28 February, on a coastwise voyage to New York with a crew of 116 and 33 observers. The draft on departure was 25 feet 4 inches forward and 27 feet 2 inches aft.

At approximately 0955 EST, 1 March, Ship A encountered fog about 25 miles north of Barnegat Lightship. The engine order telegraph was placed on "Standby" and operation of the fog whistle commenced under automatic control, sounding a prolonged blast at intervals of not more than 2 minutes. On course 004° and making a speed of 18.6 knots, the master took charge of the vessel's movements and placed

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himself at the radar, which was located on the starboard side of the wheelhouse. With him in the wheelhouse were the staff captain and a helmsman. The second officer and a messenger were stationed on the port wing of the bridge, and the third officer was stationed on the starboard wing. A lookout was on the bow.

At 1000, course was changed to 020° to avoid a southbound radar target, which passed 2 miles off the port beam at approximately 1010. At this time, Ship Awas swung left and had steadied on course 000° by 1020.

A short time later, another target, bearing 5° on the port bow, 712 miles

distant, appeared on the radar (set on the 8-mile scale). This target was observed, using the cursor bearings and range rings, but not plotted. When the target was about 4 miles away, the range scale of the radar was changed to the 4-mile scale. At 1032, when 2 miles away on the port bow, the target disappeared in the sea return. At 1032, engine revolutions were reduced to 100 RPM (18.4 knots). At about 1037, a one-blast whistle signal was heard on the port bow. Ship A was swung right to 035° (the course recorder indicated that the turn had started at approximately 1032 from a heading of 000°). At 1039, another whistle signal was heard on the port bow; both engines were reduced to 60 RPM (11.1 knots). At this time, the bow of a vessel appeared out of the fog, about one-quarter mile just off the port bow and on a course crossing at right angles to that of Ship A. At 10391/2, hard right rudder was ordered and the engine order telegraph was placed on full astern. At 1040, the bow of Ship A, going ahead and swinging to the right, struck Ship B on her starboard side, approximately 125 feet from the bow and at about right angles to her fore-and-aft line.

Ship A hit Ship B forward of her pilothouse, continued into the hull through the No. 2 starboard wing tank, crossing the centerline, and cutting the catwalk. The bow was left hanging onto the rest of the ship with only about a foot-wide strip. Ship B's bow broke off at 1115, and was later towed to the Bethlehem Shipyard in Hoboken, N.J.

Ship A was damaged at the bow. Plating and frames were torn and pushed into the forward lounge and the forepeak, with a gash extending aft about 60 feet. Also, the chain pipes, port and starboard, the forepeak tank top, and the power cables leading to all the deck machinery forward were damaged.

The masters of both vessels carried out emergency procedures. After ascertaining that no assistance was required, both vessels, escorted by tugs, proceeded into New York Harbor, each under its own power.

Ambrose Lightship, bearing 033° true, 112 miles distant. Course was set at 135°, with the speed full ahead at 1212 to 13 knots. This course and speed were maintained for approximately 5 minutes, at which time the visibility commenced to decrease. The third officer started sounding the fog whistle by hand and “Standby" was rung up on the telegraph. A few minutes later, speed was reduced to half ahead (7 to 8 knots) and the course was changed to 144o.

Two radar targets were then observed on the 8-mile range scale; one at about 412 miles and the other about 244 miles, both to starboard. The target at 294 miles was moving in the opposite direction. Its fog signal was heard and Ship B's speed was reduced to dead slow ahead (3.5 knots). The target was estimated to have passed about one-half to three-fourths mile off the starboard side. Ship B then increased speed to slow ahead (5.5 knots). Shortly thereafter, another radar target appeared about 21/4 miles on the port side as the bearing opened to the left. This target was lost in the sea return at about the 2-mile range. No fog signals were heard and it was estimated that the target passed about 112 miles off to port.

At about 1038, with visibility down to one-fourth mile, a fog signal was heard on the starboard beam. Speed was reduced to dead slow ahead (3.5 knots). Shortly thereafter, another whistle signal was heard just forward of the starboard beam; immediately all engines were stopped. About onefourth of a mile away, on the starboard beam, a vessel appeared out of the fog, bearing down on Ship B at about right angles. The engine order telegraph was rung full astern, followed immediately by emergency full astern. Ship B was about dead in the water at the time of impact.

A, and bore about 017° true when Ship A ended its turn, from 000° to a new course of 035°Ship A's new course and speed (11.1 knots) placed the two ships on collision courses (based on Ship B's course of 144o and an effective speed of about 4 knots). Thus the plot indicates a collision will occur about 3 minutes later.

The primary cause of this collision was the failure of Ship A to go at a moderate speed in a fog and failure to stop her engines and navigate with caution upon hearing forward of her beam the fog signal of a vessel, the position of which was not ascertained. These failures were aggravated by the fact that the radar provided timely notice of the proximity of the other vessel. Improper interpretation of the radar aboard Ship A was also a factor; in that, Ship A's course change (to 035°) actually placed the vessels on collision courses. This situation could have been avoided by the simple expedient of plotting ranges and bearings.

As a result of this casualty, Ship A received damage in the amount of $380,000, and Ship B damage in the amount of $900,000. There were no personnel injuries.

CASE 3

The principals in this case were a U.S. destroyer escort (Ship A) and a Swedish merchant vessel (Ship B), of 16,266 gross tons. Both ships were equipped with good operating radar. The collision occurred at about 1945 EST, 19 March, about 1.9 miles 048 true from Cape Henry Light, Va. At the time of the collision, the wind was easterly, force about 2; a light, easterly sea; the weather was clear with good visibility; and the tide was ebbing, with an east-southeasterly set.

SHIP B

SHIP A

ANALYSIS

Ship B departed Brooklyn, N.Y., at 0800 EST, 1 March, on a voyage to Aruba, Dutch West Indies. The vessel was in ballast with a draft on departure of 12 feet 10 inches forward and 21 feet aft.

At 0955, Ship B disembarked the pilot about 2 miles off Ambrose Lightship. The master was in charge of the vessel's movements and the third officer was stationed on the starboard wing of the bridge. A lookout was on the bow.

At 1000, departure was taken from

Relative motion, and the direction and distance of the CPA (closest point of approach), cannot be estimated to any reliable degree without properly plotting at least several periodic range and bearing positions of the target. In addition, the solution is accurate only when the course and speed of the target are not altered after the last range and bearing. In this case, even if the visual methods were accepted as capable of producing accurate results, the loss of the target in the sea return at a distance of 2 miles would have rendered the predicted results extremely doubtful and to be treated with utmost caution.

A relative motion plot (based on the available information) indicates that Ship B had crossed ahead of Ship

At about 1650 e.s.t. 19 March, Ship A completed exercises at sea off the Virginia Capes and began her return voyage toward the entrance to Chesapeake Bay. She was under instructions to rendezvous with an admiral's barge near Little Creek Approach Lighted Buoy “2A" for the purpose of disembarking passengers. The commanding officer and OOD (officer of the deck), a lieutenant, were on the open bridge, with the OOD in charge of the vessel's movements. A forward lookout was stationed on the signal bridge. The radar was manned in CIC (Combat Information Center).

Ship A proceeded westward, passed Chesapeake Lightship to starboard. about 1,900 yards distant; then Buoy “2” was passed to starboard, about 150 yards distant. Cape Henry Junction Lighted Whistle Buoy was passed

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to port, about one-half mile distant, at about 1938. At the time of passing this buoy, the ship's speed was 19 knots and the course was 266o.

When in the immediate vicinity of the junction buoy, the commanding officer and OOD noticed, about 15° off the starboard bow, several lights in the area of the Tail of the Horseshoe Channel. The commanding of ficer requested the OOD to check with CIC to find out if a moving target was among the lights. CIC returned a negative answer. Moving lights, which the commanding officer and the OOD accepted as coming from a ferry, were seen in this same area. However, the commanding officer, obserying that CIC had not reported a moving target, assumed that the ferry was beyond the radar range which was set on the 7-mile scale.

Approximately 22 minutes before the collision, the commanding officer observed the masthead lights and red side light of a vessel, which bore about 40° off the starboard bow. The OOD attempted to take a bearing, but the assistant navigator was using the starboard pelorus. He then viewed the lights by binoculars, and estimated the distance to be about 2,000 yards. The commanding officer, about this time, stopped the engines. A few seconds later, after hearing a four-short-blast whistle signal from the other vessel, he ordered "left full rudder-all engines back full," sounded four short blasts on his whistle, then sounded the collision alarm. The commanding officer then heard what he thought was another four-blast signal from the other vessel. Ship A began to turn left and the bow of Ship B passed down the starboard side of Ship A. When about 100 feet away, the commanding officer ordered “rudder amidships—all ahead full." But, a few seconds later, Ship B struck Ship A on the starboard side, abaft of amidships.

Ship A was able to prevent progressive flooding and remained afloat. The injured and deceased personnel were cared for, and the vessel was later towed into the port of Norfolk, Virginia. Ship B remained in the area, and later proceeded into Norfolk.

CASE THREE

buoy "ITH” about 800 yards to port. The engines were stopped, and the vessel placed on a heading of 160° in order to make a lee for the pilot's departure. At about 1940, 19 March, with the engines stopped and the vessel moving through the water “a little,” the pilot departed.

While Ship B was heading about 165°, the master, who was now in charge of the movements of the vessel, observed the masthead lights and the green side lights from a vessel 10° to 20° forward of his port beam. This vessel was Ship A. The master then ordered ahead full and ordered the man at the helm to come left to 115°. As Ship B approached this course, the master, wishing to pass Buoy “2A" abeam to port, distant one-half mile, observed the buoy on radar and decided the correct course to pass onehalf mile off was 125° (after having been on 115o "just a short while").

As Ship B approached Buoy “2A”, the master observed the masthead lights and the red side light of another vessel almost dead ahead and several miles away. He decided to come right in order to leave room between his vessel and Buoy “2A" for the latter oncoming vessel to pass. He then came to course 134°.

When Ship B had Buoy "2A” abeam, Ship A was approximately 50° off the port bow of Ship B and still

closing. The master, at about this time, ordered his chief mate to sound the danger signal and stop the engines. Both orders were executed. Failing to observe any change in maneuvering by Ship A, the master sounded one long blast and ordered hard right. As Ship B began turning right, the master, observing that Ship A was still closing so as to cross ahead of Ship B and thinking that he could not avoid collision by going right, ordered hard left and half astern. The right rudder had been held for about one-half minute. As the bow of Ship B was about amidships of Ship A, the master, seeing that the vessels would not clear, ordered full astern, just before the impact.

ANALYSIS

SHIP B

Ship B departed Baltimore, Md., bound down Chesapeake Bay en route to Puerto de Hierro, Venezuela. On board was a State pilot who was directing the movements of the vessel. The run dow the bay was completed without incident. While approaching the area where the pilot was to disembark, Ship B was navigated to the westward of Tail of the Horseshoe buoys, “3TH" and "1TH," so as to pass

The available information indicates that earlier visual detection of Ship B was hampered by background lights which were visible beyond the port bow to the starboard bow of Ship A. In addition, the question of a proper lookout is also raised. An 18-year-old seaman, standing his fourth lookout watch, was the forward lookout. His position on the signal bridge made it even more difficult for him to see another ship's lights among all the background lights. In any event, he failed to see and report any moving targets to CIC. A lookout on the bow would probably have seen Ship B much earlier.

Radar was also a factor in this case. Although the reason Ship A failed to detect the presence of Ship B by radar was not evident in the record, there can be little doubt that the speed of the vessel was influenced by the absence of any reports from radar of moving targets ahead.

The master of Ship B, watching Ship A approaching off his port bow, expected Ship A to come right and pass to port of Ship B. However, in the absence of signals, or other communication, no vessel should attempt to predict the intentions of the other. Ship A being the burdened vessel, had the duty to keep clear. Therefore, when her commanding officer first observed the red side light of Ship B about 2,000 yards away on his starboard bow, he should have given a one-blast signal and then altered course to pass astern of Ship B. An exchange of signals was indicated under Section 80.3, Pilot Rules for Inland Waters.

This was a crossing situation in which the proximate cause of the collision was the failure of Ship A, the burdened vessel, to keep clear. Factors contributing to her failure were background lights hampering visual detection of Ship B's lights and the reported absence of a moving target on radar. Obviously, the CIC failed to maintain a plot, and based its report solely on radar presentation in the absence of reports from the forward lookout. A plot would have disclosed the proximity of Ship B in ample time to take proper evasive action.

As a result of this casualty, two crewmembers of Ship A were killed and one seriously injured. Ship A suffered structural damage estimated at about $350,000; damage to Ship B was estimated at about $35,000.

CASE 4

The principals in this case were a U.S. merchant vessel (Ship A) of 7,632 gross tons and a U.S. fishing vessel (Ship B), a motorboat, of 23 net tons. The merchant vessel was

equipped with good operating radar. The weather at the time of the casualty was: wind from the northwest at force 5; approximately a 9-foot sea from the northwest; and dense fog.

SHIP A Early on the morning of 27 September, Ship A, en route San Pedro, Calif., to Seattle, Wash., was proceeding northward off the Washington coast at 11.5 knots. The master and second officer were on the bridge. At 0720 PST, a fog bank was observed ahead about 4 miles away in the vicinity of Tatoosh Island. A lookout was posted on the bow and fog signals were commenced. The engine was placed on "Standby", but no reduction in speed was made. The radar was on and appeared to be operating satisfactorily, showing a good presentation of land mass, but no vessel targets were observed. At 0734. Tatoosh Island was abeam to starboard, and the vessel had entered the fog bank where visibility was between 500 and 1,000 yards. At 0746, with Tatoosh bearing 145o true, distant 3 miles, the master ordered right rudder to enter the Strait of Juan de Fuca. At this same time, the lookout reported by phone that he heard a whistle ahead. Immediately, the engine was stopped and the master checked the radar, which was on the 8-mile scale, but observed no vessel targets. Approximately 142 minutes later, the lookout reported sighting a vessel 1,000 feet ahead fine on the starboard bow. This later proved to be Ship B, which appeared to be underway with little or no way on and heading across the bow of Ship A from starboard to port. Upon receiving the report from the lookout, the master ordered full astern. The rudder was already hard right. The response to the engine order was immediate, but these maneuvers did not succeed in evading Ship B. At about 0750, with Ship A making an estimated 3 to 4 knots through the water, her bow struck and holed Ship B on the port side near the forward end of the pilothouse.

Ship A was undamaged, but Ship B was severely holed and sank about 3 minutes after the collision. Ship A came about, lowered her motor lifeboat, and was able to rescue three survivors. Unfortunately, the master and one crewmember of Ship B were lost.

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SHIP B

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Ship B, a 49-foot, wood hull motorboat, licensed for fishing, with the master and four crewmembers aboard, departed Neah Bay, Wash.. at about 0600 en route to the fishing

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grounds near Destruction Island at the entrance to the Strait of Juan de Fuca. After clearing the harbor, the vessel headed west at half speedapproximately 5 knots-into a 9-foot westerly swell. At about 0720, fog was encountered. The master came to the bridge, took the wheel, and began sounding fog signals. Five minutes later speed was reduced to 4 knots. Sometime later, the master ordered the stabilizers rigged to reduce the vessel's roll, as the seas had increased. The man who previously had the wheel had remained in the pilothouse. At this time, he went below to call two other crewmembers to assist in the rigging out. Afterward, while waiting for the others, he was standing on the foredeck acting as lookout. He had been there 2 to 3 minutes when he heard the master shout “Look out!" Shifting his gaze from right to left, the lookout saw the bow of Ship A about 50 to 60 feet away and felt the engine of Ship B being reversed and the revolutions increased. Within seconds, the collision occurred.

forded by available reflector equipment is definitely limited and offers no assurance that vessels so equipped will be observed by radar in time to avoid collision or even that they will be observed at all. However, it appears that owners of small vessels, particularly those of nonmetallic construction, should be encouraged to employ any means which might improve radar detectability.

As a result of this casualty, Ship B sank with an estimated loss of $65,000. The master and one crewmember of Ship B were lost and presumed dead; one crewmember was injured. Ship A was not damaged.

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ANALYSIS

The principal cause of the collision was the failure of Ship A to go at a moderate speed in fog. In this connection, it is apparent that undue reliance was placed on the fact that no vessel targets were observed on the radar and that the radar appeared to be working properly. The record does not indicate whether or not any attempt was made to periodically shift the range scale; such a procedure is often successful in detecting targets not visible on one range scale alone.

There is the question of a proper lookout aboard Ship B. The crewmember who was relieved at the wheel by the master indicated that he remained in the pilothouse until he went below to call the other crewmembers. When he returned topside he took position on the foredeck to act as lookout, and within 2 or 3 minutes the collision occurred. During his absence, Ship B had no lookout. Had a lookout been stationed on deck well forward and away from any distractions at the time fog was first encountered, there remains the possibility that he might have heard the fog signal of Ship A, thereby providing additional time in which to take avoiding action.

The board investigating this casualty was of the opinion that the use of a radar reflector aboard Ship B may have made her a more effective radar target. Tests conducted by the U.S. Coast Guard indicate that the increase in radar detectability af

CONCLUSIONS In a study of collision cases certain conclusions appear obvious. For example, the greater number of collisions occur in narrow channels and other congested waters. At the same time, an important contributing cause is a marked inclination to ignore some of the established rules for avoiding collisions. The latter is convincingly illustrated by a study, completed in 1960, which showed that, of 199 collisions studied, there were 105 violations of article 18, Inland Rules (approaching steam vessels). Fiftyfive of these were violations of article 18, rule I (meeting and passing, and whistle signals), and 30 were violations of article 18, rule III (danger signals). Failure to make a normal port-to-port passing, where clearly indicated in a meeting situation, is often aggravated by excessive speed and failure to give proper signals, including a failure to sound the “danger signal", as prescribed by article 18, rule III.

In the study previously mentioned, of the 11 causes considered, excessive speed was a contributing cause in 77 cases. Reference to the study report also discloses that being on the wrong side of the channel was a contributing cause in 58 cases, and failure to sound signals a contributing cause in 45 cases. However, 33 collisions occurred even though a passing agreement had been reached.

The study further emphasized the relatively small number of collisions which result from poor visibility. Of 199 collisions, less than 27 percent occurred when visibility was less than 2 miles. In most instances human factors, rather than physical ones, were responsible for the resulting collisions.

The use of radar information as a help in preventing collisions, particularly in open-sea situations and situations of low visibility, has been a subject of growing importance. Recognizing that this aid is effective only when properly used, the Fourth

International Conference for the Safety of Life at Sea (1960) adopted certain additions to the Rules of the Road which contemplate the proper use of radar at sea. Applicable portions of the proposed changes and the annex to the rules are reproduced at the conclusion of this article.

Case 2 is an impressive example of the misuse of radar information. Ship A relied on unplotted ranges and bearings as a means of determining the movements of Ship B. It should be remembered that in a relativemotion presentation, such as is given by most PPI scopes, the course and speed of the other ship can be determined only by plotting several successive ranges and bearings. A single reading of another ship's range and bearing fixes its position only for that particular instant. It does not provide enough information upon which to take avoiding action, since it cannot predict any future position. The officer directing the movements of Ship A (case 2) erroneously assumed he had the ability to deduce the other ship's movements from the radarscope presentation. Later, when the other ship disappeared in the sea return at a range of about 2 miles, its subsequent movement could not be predicted. As a consequence, Ship A's turn to starboard actually produced a collision. A relative-motion plot establishes quite conclusively that the collision would not have occurred had Ship A continued on her original course.

Certain research and tests have been undertaken to develop automatic plotting and evaluation of multiple radar targets; for example, by appropriate inputs to a monitoring electronic computer. Preliminary tests have been encouraging, as have other

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