1. Overview
Chapter 9 gathers the special maneuvers that fall outside ordinary docking and undocking: handling a ship in canals and locks, mooring to single- and multiple-point buoy systems, ship-to-ship lightering, the Mediterranean moor, the Williamson Turn for man overboard, the peculiarities of twin-screw and low length-to-beam ships, and the step up to handling VLCCs, replenishment at sea, and helicopter operations. Each is a distinct evolution, yet all rest on the same foundation laid earlier in the book.
The recurring lesson is that none of these maneuvers requires new physical laws. A ship in a lock, at a buoy, or alongside a VLCC obeys the same hydrodynamics as a docking vessel; the differences are of magnitude and timing, not character. The accomplished shiphandler plans ahead, uses external forces — wind, current, quickwater, and interaction — to advantage, and does the job in the manner with which he is most comfortable.
2. Canals and Locks
Mariners routinely handle ships through canals and locks, from tidal-basin locks at Bombay or Buenos Aires to the Panama or Welland Canal. Each passage is unique, but the common problems are best understood through the Panama Canal, which presents a composite of conditions found at most lock-type facilities: fresh- and saltwater sections, single and multiple locks, and a restricted channel with all its inherent effects. A lockage divides into four segments — the approach, entrance, fill, and departure.
2.1 Currents at Locks
It is a common misconception that there are no currents in lock canals. In fact strong currents can reach 3 to 4 knots at the lock's entrance, or jaws. Two currents matter. As a chamber is lowered, a huge volume of water flows out as a spill current — primarily a surface current whose effect varies with the ship's draft. Where a lock joins two bodies of different density, opening the gates lets the heavier water displace the lighter and a density current forms: at the surface it resembles the spill current, but below the surface the heavier water flows the opposite way, toward and under the lighter fresh water. At the Panama sea entrance the displaced fresh water flows out in a strong surface current reaching down 20 to 25 feet.
2.2 The "S" Approach
Because of this combined current pattern, ships approach the Panama locks on an "S" pattern to compensate. The current flows strongly for about thirty minutes after the water stops spilling, so the gates may be held closed until the ship is almost to the jaws and the bow wires are fast, or the current is allowed to dissipate before a large Panamax ship approaches. The distance held off the center wall varies with ship size, current strength, and draft: smaller ships approach the wall near the jaws and bring the stern in as the bow enters; deeply laden or Panamax ships are kept close, with the bow or entire ship held hard against the center wall before the chamber is reached.
2.3 Gear, Tugs, and the Knuckle
At the locks the ship supplies only an officer and crew forward and aft to work the line-handling winches, plus two mooring lines at each end in case she must tie up; canal seamen supply the rest. Other waterways, such as the Welland Canal and Saint Lawrence Seaway, require the ship to supply all gear and handle her own lines, so local rules must be read carefully. Communication is by walkie-talkie, with hand signals as backup and the whistle for a danger signal. Anchors are kept ready but stowed in the hawsepipe, not backed out, so wires and messengers do not foul the flukes. Tugs hold the bow or midbody against the center-wall fendering to keep the current from forcing the bow into the knuckle — the corner where the side approach wall meets the chamber's side wall.
2.4 Two Valid Methods — and the Lesson
| Method | Technique | Rationale |
|---|---|---|
| Whole ship alongside | Hold the entire ship flat to the wall with locomotives and tugs until the forward midbody is inside. | Keeps the hull as far as possible from the knuckle; tight alongside, no current can get between ship and wall. |
| Bow alongside, stern off | Hold the bow alongside but let the stern stay a few feet off while sliding in. | If the bow gets off it returns easily because water flows astern instead of being trapped; needs only one slow tug. |
Both methods have put thousands of Panamax ships safely into locks for nearly a century. Which is best? The one the pilot is most comfortable with. The point is broader than locks: there is rarely only one right way to do a shiphandling job, as the variations among the finest pilots demonstrate.
2.5 Wires, Piston Effect, and the Fill
Wires are taken from the locomotives — the "mules" — as the ship passes the center wall, the number set by an empirical formula based on displacement and length. Each locomotive exerts up to 70,000 pounds of pull through its constant-tension winches and a drive that meshes into a rack between the tracks; mules positioned ahead of the chock tow and center, while those abeam or abaft brake. Larger ships must be driven in, often at full ahead, because their beam and draft fill the chamber's cross-section so the displaced water cannot escape, creating a piston effect that practically stops the ship on her own once engine and mules stop. During the fill the gate valves open and water flows through lateral culverts beneath the ship. An up lockage surges heavily as water rushes in; a down lockage is quiet. Filling from the bottom is preferable, the motion being mainly vertical. The ship must be held centered or alongside throughout and never allowed any athwartship movement, or she will surge and strike a wall.
2.6 Departure
As the gates open the ship steams out with engine and mules; a large ship is "flushed out" by water put into the chamber behind her, so the displaced water need not squeeze past the hull. Clearing the jaws, she is put at an angle with the bow away from the center wall to balance the suction on her quarter as she passes along the wall — the wall acting like the close bank of chapter 2. The currents at the seaward end of the locks help a departing ship clear the wall.
3. Panama Canal Expansion Project
The expansion's largest effect is the ability to handle larger vessels, driving construction of ships built to the new lock parameters. The original 1914 locks were 1,050 ft long, 110 ft wide, and limited Panamax ships to 965 ft length, 106 ft beam, and 39.5 ft draft. Neo-Panamax (New Panamax) vessels reach 1,200 ft length, 160.7 ft beam, and about 49.9 ft draft — roughly 13,000 TEU versus the Panamax 5,000 TEU.
| Dimension | Original locks / Panamax | New locks / Neo-Panamax |
|---|---|---|
| Lock length | 1,050 ft (320 m) | larger (Agua Clara / Cocoli, three chambers each) |
| Lock width | 110 ft (33.5 m) | wider |
| Max ship length | 965 ft | 1,200 ft (366 m) |
| Max beam | 106 ft | 160.7 ft (49 m) |
| Max draft | 39.5 ft | ~49.9 ft (15.2 m) |
| Capacity | ~5,000 TEU | ~13,000 TEU |
The new locks differ in more than size. There are two sets — Agua Clara on the Atlantic, Cocoli on the Pacific — each with three chambers and a series of water basins to recycle water. Locomotives are replaced by tugs, placing greater reliance on the pilot's skill, and there is no approach wall on the Agua Clara locks from the Gatun Lake side. Officers and pilots have trained on simulators and gained hands-on experience; DGPS-based piloting units and other electronic aids let them maneuver these vessels more precisely.
4. Single-Point Moorings
Few ports can take deeply loaded VLCCs and ULCCs, so offshore terminals such as LOOP in the Gulf of Mexico use single-point moorings (SPMs). LOOP lies in 100 to 125 feet of water about 19 miles off the Louisiana coast, reached via a fairway under a pilot/mooring master. After a prearrival inspection the ship is turned to her final mooring heading and brought up to the buoy.
4.1 Finding the Approach Heading
The best indication of the required heading is the direction in which the floating cargo hoses trail from the buoy. From the anchorage, approach on the heading the ship was lying; from sea, approach straight up the hoses, which lie to a resultant of surface current and wind. Since tugs are not generally used, the ship must approach on a heading that balances wind and current or she is set away before the lines come aboard. Despite the VLCC's great draft the current does not simply overcome the wind: VLCCs have a great sail area, and even a 15-knot wind significantly affects the heading.
4.2 "In the Groove"
Outside forces increase geometrically as headway falls to the less-than-1-knot speed needed to complete the evolution. Once the proper heading is found the ship holds it without much rudder and does not set away; the buoy stays at the same relative bearing fine on the port bow. This feel of being "in the groove" is one of the best signs the heading is right. A Doppler log reading lateral and fore-and-aft speed over the ground is especially helpful. Plan one large change of heading in the last stage rather than a series of small ones: the ship can then run at 3 to 4 knots until the course change instead of 1 to 2 knots throughout, covering the last 2 miles in about an hour.
4.3 Picking Up and Making Fast
The ship is steadied on her final heading well before the buoy, since there are usually no tugs to check residual swing. During the final 600 feet the crew heaves the pickup line aboard so the ship can be stopped 100 feet from the buoy; the pickup line brings the chafing chain aboard, made fast with a chain stopper or Smit bracket. The chain stopper is preferable — it has no connecting links or shackles, so the mooring is faster and safer. The pickup hawsers must not be used to heave the 350,000- to 600,000-ton ship to the buoy; the ship is steamed to the buoy and the lines only bring the chain aboard.
4.4 Hose Side and the Bow Pilot
The hoses and buoy are kept on the ship's port bow so she passes clear if the stopping distance is misjudged: the port bow is chosen because the bow swings to starboard, away from the hose and buoy, when the engine is put astern. The boat is not to pull the hoses clear to port until the ship has nearly reached them, since the hose string sets the approach heading. Within a few hundred feet the buoy is no longer visible from the bridge, so an assistant mooring master on the bow conns the ship by walkie-talkie and should himself be a qualified pilot.
4.5 During Discharge
A mooring line is kept ready aft for the workboat to hold the ship off the buoy during discharge; constant attention prevents the ship riding up on the hoses, usually requiring the engine astern at 8 to 10 revolutions or a boat pulling astern. Because wind and current are usually at an angle, the ship "sails" up to and across the buoy much as she tacks across her anchor. A loaded VLCC is affected by the wind as much as a smaller ship, presenting the same sail-area proportion. Except in the worst weather a ship can make up and stay at an SPM; the primary limit is the sea state during makeup, since moderate seas stop the line boats handling the hoses.
5. Ship-to-Ship Lightering
A great deal of offshore lightering is done worldwide, especially off the United States, where shallow ports make it necessary so oil can be imported in very large crude carriers. It is less efficient than fixed terminals but a workable substitute. The smaller ship that takes the oil is the "offtaker"; here VLCC includes the ULCC.
5.1 Rigging the Fenders
Fenders are rigged on the port side of the offtaker — not the VLCC — so the smaller, maneuvering ship is sure to land on them; were they on the VLCC, the offtaker could land between fenders and damage both ships. Two types are used: four or more large floating "Yokohama" fenders along the parallel midbody, and two smaller "pillow" fenders at the forward shoulder and the quarter. Mooring lines must have synthetic tails so the ships can break apart quickly in an emergency and the tails absorb shock; they can be cut as a last resort.
5.2 The VLCC's Job and the Approach
The mooring master aboard the offtaker has overall command; the second master aboard the VLCC holds a steady course and speed, steaming into the wind and sea at minimum speed and only kicking ahead to keep steerageway. This minimizes the accelerated flow between the ships that would draw them together and cause a heavy landing. The offtaker approaches the starboard side of the VLCC, staying wide until abeam of the flat parallel midbody. It is vital to keep clear of the VLCC's quarter, where suction would draw the offtaker rapidly in.
5.3 The Wind as a Tug
When parallel and both heading into the wind, ease the smaller ship alongside using the wind as a tug: keep the wind on the starboard bow to bring her alongside, or shift it to the port bow if she closes too fast. The wind has a strong effect because the offtaker is light before loading. Land flat on all floating fenders simultaneously to spread the force and create the maximum hydraulic cushion to check the lateral motion. The offtaker passes a forward spring first, then two headlines to work against, then the rest.
5.4 Suggested Lines and Holding On
| Ship | Lines run |
|---|---|
| Offtaker | 5 headlines, 2 forward springs, 2 after springs (leading forward to the VLCC), 3 sternlines. |
| VLCC | 3 wire headlines, 2 forward spring wires, 2 stern wires — plus 2 good springs from the manifold area leading aft to tow the offtaker. |
Always run all lines regardless of the weather, since running lines is slow and may be impossible later. If weather permits, anchor the VLCC before hooking up; stop using minimum revolutions astern, drifting headway off rather than backing hard, so the offtaker's momentum plus the quickwater rising between the ships does not force them apart and part their lines. Keep the wind and sea a point on the VLCC's port bow so she makes a lee. The ships stay together unless a sea makes them roll and risk parting lines or hoses — break up before conditions deteriorate, never after lines start to part.
5.5 Breaking Apart
When transfer is done, let go the VLCC's lines and single up the offtaker to two headlines, a forward spring, an after breast line, and the after main-deck spring leading forward — this last spring keeps the offtaker from sliding aft under the VLCC's quarter and is the last line let go. With no wind, heave the after breast line to bring the bow off, then work against the spring to open an angle, and steam slowly away keeping the wind on the inner bow as the "poor man's tug." If already underway, use the water passing between the ships to separate them, and do not increase speed until well clear, which would draw them together again.
6. Five- and Seven-Point Moorings
Used primarily on the US west coast, where deep water lies close to shore, these moorings sit 0.5 to 1 mile offshore over submarine hoses. The ship moors under a mooring master using two bow anchors and ship's lines to buoys lying abeam and astern. Five-point moorings take ships to 35,000 tons; seven-point to 165,000 tons; tugs may assist ships over 80,000 tons deadweight. The ship prepares up to fourteen synthetic lines (two per buoy), both anchors backed out and ready, hose-handling gear at the manifold, good stoppers, and walkie-talkies fore and aft.
6.1 The Approach and Laying the Anchors
The ship approaches on a heading about 90 degrees to the axis of the berth, along the line the anchors will lie. Because the mooring faces the prevailing wind and sea, the approach is usually made with the wind and sea on the beam, which may force higher speeds than otherwise wanted. The offshore anchor is let go at command, with all seven to nine shots run out immediately. Do not check the chain, which would pivot the ship on the anchor and might drag it; just the chain's drag steadies the bow and shifts the pivot point forward, altering the ship's behavior.
6.2 Steering Astern With Two Anchors
The ship carries her headway past the berth axis before stopping and letting go the second anchor; she is swung and maneuvered into position, not backed and filled. The swing put on before the second anchor is critical, allowing for the ship's tendency to back to port. The key directional rule:
The ship goes astern while the anchors assist steering, slacking each chain as required, and the lines are run to the buoys by the line boat. Do not turn the propeller while lines are out except by the mooring master's direct order. The first line is usually a breast line from the windward or up-current side, then the rest; double stoppers are used where strain is heavy. With all lines out, a strain is taken on both anchors to position the ship over the hose — the anchors forming an equilateral triangle holding her into the weather.
6.3 Staying and Departing
The mooring master advises on whether to stay if conditions deteriorate — a heavy responsibility, since when the weather is from ahead the strain is on the anchors and the ship can stay longer, but from other directions the strain shifts heavily to the lines. A loaded ship departs by taking lines aboard roughly in reverse order, heaving the anchors as the breast lines go, then steaming away. A light ship heaves the starboard anchor short, works against it while heaving the port anchor to keep the bow into the wind, and is driven out dragging both anchors until clear — she must not fall off the wind or she winds up on the buoys.
7. Mediterranean Moor
Once used only in less-developed ports, the Mediterranean moor is now common for RO/RO ships with stern ramps that berth stern to the quay with anchors laid out ahead. The procedure for the five- and seven-point mooring is the most efficient way to complete it: make a proper approach, lay out the anchors, and back into the berth using the anchors to steer. Ideally the anchors are spread at 60 degrees so the bow is held regardless of wind direction, with the chain and spread forming the legs of an equilateral triangle; the ship is moored with at least one shot more chain than for anchoring in the same depth.
7.1 Allowing for Weather and Backing In
Unlike a five-point mooring, a cargo berth is rarely built for the prevailing weather, so the forces commonly come from some direction other than ahead; allow for set and leeway by adjusting the swing put on before the second anchor and by holding one anchor or the other while backing. The mate aft must report the bearing and distance from the stern to the berth — and the rate of change — since RO/ROs have the bridge well forward. Run the stern lines early, then back as the mate walks the chain out under light strain. Keep the stern lines clear of the propeller, and do not use the engine to back the last few feet — heave the ship astern to avoid an accident from delayed engine response. Heave the chains partly out of the water so the ship cannot move astern if the weather later changes.
7.2 Bow Thrusters and Departure
A reliable bow thruster greatly simplifies the moor — it positions the bow before each anchor is let go and steers the ship astern, even letting her lay out the anchors without being perpendicular to the berth when room is tight. No ship that works cargo over the stern should be built without one. To depart, take in the stern lines and heave the windward anchor short to two shots, then heave the lee anchor while steaming against the weather anchor; start ahead as the lee anchor breaks free, dragging both anchors clear before heaving them home.
8. Williamson Turns
The classic Williamson Turn puts a ship on a reciprocal heading and is especially useful as ship size increases. Ships with high block coefficients lose headway fast, and a VLCC will typically have lost most of her headway by the time she reaches the reciprocal course, needing little astern work to stop and pick up a person or object. Because the path is predictable, it is preferable to a round turn for reaching a reciprocal heading.
8.1 Eliminating the Variables
The classic instruction to steady up after 60 to 65 degrees of swing is unreliable, because the time to check the swing and the rudder used depend on the helmsman's judgment, so the track varies. It is better to shift the helm at a predetermined point and leave it there. The fixed 60-degree figure suits no single ship: a directionally unstable, deeply loaded tanker following it would swing well past and never return to her track. The shift point must be found by trial and error during routine emergency drills. One particular VLCC returned to her own wake when the rudder was shifted at 35 degrees from the initial course, with the rudder then put hard over to check the swing 15 degrees from the reciprocal.
8.2 The Three Helm Orders
Only three rudder movements are needed, all at defined points independent of the watch officer's judgment. The engine speed is not changed during the turn (though put on standby): maintaining revolutions keeps the rate of turn predictable and returns the ship in minimum time, while speed is still sufficiently reduced. Above all, the person or object in the water must be watched at all times — more important than the perfect turn — and a light, dye marker, smoke, or life ring thrown close by, with a light essential at night. In one trial a VLCC returned to the original spot in eleven minutes, making 4 knots at the reciprocal though the engine ran full throughout from an initial 19 knots, and was easily brought dead in the water.
9. Twin-Screw Ships
There is a misconception that twin-screw ships inherently handle better than single-screw ships. This is not necessarily so. The propulsion type and the number, configuration, and location of the rudders govern handling. Older turbine-driven twin-screw ships with single rudders "handle like water-soaked logs," while modern diesel twin-screw ships with twin rudders and thrusters are excellent. Twin screws are found mainly on passenger vessels, to cut vibration at higher power and ease maneuvering in small harbors.
9.1 Engine Response and Twin Rudders
Diesel twin-screw ships respond faster than turbine ones, so kicking ahead to move the stern without gaining headway works better, as does twisting within the ship's length using one engine ahead and one astern. Twin-screw, twin-rudder ships are inherently more responsive at slow speeds, because the twin rudders sit directly behind the propellers and the propeller wash flows over them. Without that flow a single rudder has little effect until the ship gains headway. Notably, twin-screw single-rudder ships often steer better at very low speed with the engines stopped: stopping removes the spread propellers' directional stability that otherwise counters the rudder. If such a ship behaves poorly at slow speed, try stopping the engine rather than working one screw against the other.
10. Maneuvering Twin-Screw Ships
With well-separated shafts — especially on a diesel ship — a twin-screw vessel can be turned within her own length by working one engine ahead and one astern: port engine ahead and starboard astern turns the ship to starboard. Because a propeller is more efficient turning ahead, fewer revolutions are usually needed on the ahead-turning shaft to turn while holding position.
10.1 Moving Laterally Toward a Berth
To move bodily toward a berth, the outboard propeller (away from the dock) turns astern while the inboard turns ahead; both then rotate the same way but thrust opposite, walking and twisting the stern toward the berth without headway, while a tug or thruster pushes the bow over. Before landing, the rotation is reversed to check the stern's lateral motion so the ship lands gently. Outboard-turning propellers are usually more effective at moving the stern: docking starboard side to, the starboard screw ahead (clockwise) walks the stern toward the dock, and the port screw astern (a left-hand screw turning clockwise in astern) also walks the stern to starboard.
10.2 The High-Powered Twin-Rudder Special Case
Very high-powered twin-screw, twin-rudder ships — naval craft, supply and research vessels, big passenger ships — can be moved laterally without a tug or thruster by a method that seems to contradict the above. To move toward a starboard-side dock, the rudder is put hard left to drive the stern to starboard, but the port engine turns ahead and the starboard astern to move the bow to starboard. Rudder and engines oppose each other: the rudder overrides the engine forces on the stern (moving it to starboard) while the two cancel at the bow, so the ship holds her heading and moves bodily to starboard.
10.3 Shallow Channels, Unbalanced Engines, and Berths
In a shallow channel one shaft's revolutions may need increasing to compensate for restricted flow to the screw nearer the bank; a twin-screw ship is more likely to take a sheer there, and harder to recover, than a single-screw ship, so watch for large or repeated rudder angles as signs of suction. Plan to start one engine before the other on a motor ship and set up for the worst case. Near a solid-faced berth, the inboard screw astern lifts the quarter and keeps the ship off prematurely, the quickwater lifting the ship as with a single screw. Because twin propellers are set off center and more exposed — sometimes near or outside the hull line — guard against any angle that lets a propeller touch the berth, keep stern lines clear of the screws, and place after tugs clear of them, perhaps on a hawser. The triple-screw design overcomes much of this: the center shaft is used for maneuvering like a single-screw ship and the outboard engines only at high speed in open water.
11. Low Length-to-Beam Ratio Ships
Carrying capacity can be increased without more draft by adding length or beam. Where length is already maxed by port limits, increasing beam reduces the length-to-beam ratio and decreases directional stability, so more rudder is needed to check and steady the ship — though the turning circle becomes smaller. Such ships usually demand great attention, yet some recent designs handle superbly.
11.1 The VMax VLCC
The VMax VLCC is the example. Built for maximum capacity within the Delaware Bay and River channel limits, these ships are 1,100 feet long with a 230-foot beam — an L/B of 4.8:1, versus 5.5–6:1 for other VLCCs and 8:1 for an 850-foot Panamax. By theory such a low ratio should respond poorly to the rudder, yet masters report the opposite, because the VMax is fitted with twin skegs, twin rudders, and twin screws set as far outboard as practical, with a cut-away stern placing the rudders at the extreme end of the submerged area.
11.2 Handling and Cautions
The twin-skeg/rudder arrangement improves directional stability and gives a far larger turning force than a single centerline rudder. Less rudder starts a turn, the rudders are left on longer, and less rudder checks the swing; the ship keeps steerage long with engines stopped and holds a nearly constant heading backing with both engines. The rudders can be used separately at slow speed — using the rudder on the same side as the ahead-turning engine, the other rudder amidships, enhances the twisting effect. Cautions remain: their extreme breadth requires planning meetings and overtakings for straight reaches; even small heel in turns increases draft, so the maximum draft is cut to 38 feet versus 40 for most tankers; and, as with any twin-screw ship, care is needed near berths, with lines near the stern, and with tugs aft.
12. Moving Up to Larger Ships
The handling of VLCCs and ULCCs is surprisingly similar to that of smaller ships — the Esso Osaka tests confirmed it. Especially valued is their ability to steer at very low speed with minimal engine use. The differences are of scale and timing, not character: very large ships obey the same laws of hydrodynamics.
12.1 Stopping, Tonnage-to-Horsepower, and Course as the Answer
Stopping distance changes geometrically with size, worsened by the high tonnage-to-horsepower ratio of VLCCs — displacement has grown far more than power.
| Vessel | Displacement / horsepower | Ratio |
|---|---|---|
| VLCC | 380,000 tons / 40,000 hp | 9.5 |
| Bulk carrier | 80,000 tons / 16,000 hp | 5.0 |
| Containership | 65,000 tons / 60,000 hp | 1.1 |
It is no longer practical to rely on engine power alone to stop, but VLCCs can be handled safely in restricted waters by planning ahead. In a close-quarters situation a VLCC's most effective response is an alteration of course, not a reduction in speed, using her excellent steering to offset her low backing power; the COLREGS recognize maneuverability in setting safe speed. A VLCC moving at less than 2 knots still needs more than a ship length to stop.
12.2 Seaway, Shallow Water, and "Constrained by Draft"
A VLCC is affected differently by the sea: a head sea that makes a small ship pound is hardly felt on the bridge, yet sets in the bow plates, and the panting, slamming, hogging, sagging, and wracking stresses are actually much greater. The mariner must reduce speed or alter course to ease these stresses even when the motion does not show them, relying on sea sense. Shallow-water effects are felt sooner and in deeper water, since the VLCC's draft is often twice the average. The COLREGS define a vessel "constrained by her draft" (Rule 3.h) when she is severely restricted in deviating from her course — properly interpreted to include not only grounding limits but shallow-water effects that degrade maneuvering.
12.3 Docking the VLCC
In port the mass and hull form matter more, bottom effects increase, and reaction time lengthens, so the shiphandler must think still further ahead. Forward speed is hard to judge from the great height of eye, so without good instruments he must err on the safe side and move very slowly. Some adjustments in technique:
| # | Adjustment when docking a VLCC |
|---|---|
| 1 | Tugs are less effective. |
| 2 | It is impractical to warp a VLCC alongside using ship's lines only. |
| 3 | Stop farther off the pier and push alongside, to land flat on the stringpiece or clusters. |
| 4 | Minimum lateral speed is essential to land without damage. |
| 5 | Doppler indicators showing lateral as well as ahead/astern speed are essential. |
The ship must come alongside flat so the landing force is spread over the midbody and the maximum frames. Her length makes this harder: perspective — the "railroad track" effect — makes the bow appear closer than the stern when both are equidistant. Watch the rate of closing forward and aft rather than the apparent distance off. No new skills are required for a VLCC, only greater attention to advance planning and patience for the ship to respond.
13. Replenishment at Sea
A small but growing number of ships replenish at sea. The ship that holds course and speed is the "large ship"; the other is the "maneuvering ship." Planning is by radio, choosing a base course and speed that puts the sea two points on the bow away from the operation to make a lee and minimize rolling and yawing. The steering gear is tested, a seaman is stationed in the steering flat ready to shift to local steering, and a good helmsman is assigned.
13.1 The Approach and the Danger Zone
Within half a mile the maneuvering ship comes to a heading parallel to the large ship's wake and adjusts speed to about 3 to 5 knots greater. Interaction is greatest as the maneuvering ship's bow passes the large ship's quarter — this "danger zone" should be passed through before reducing to base speed, to keep good rudder control while in it. Merchant ships should not back down to slow, as on the higher-powered naval ships, because backing badly affects their steering and their backing power is insufficient; instead they hold the higher speed until past the zone, then reduce and slowly lose headway to base speed.
13.2 Alongside and Departing
About 100 feet separation is generally proper. Do not let the constant-tension winches pull the ships together; the maneuvering ship heads a few degrees away to offset the winch pull and the suction between the two moving ships. A marked distance line is passed forward to hold separation, then the highline and rigging. Steer by giving the helmsman headings, not helm orders, to keep changes minimal so no radical swing develops. To depart, open the bow angle slightly and let the ship come away, increasing revolutions only enough to overcome the loss of speed from the heading change. Do not pass ahead of the large ship, and do not increase speed through the water until well clear, which would increase suction.
14. Helicopter Operations
Helicopters, once only for medical evacuation, are increasingly used for crew changes and storing VLCCs en route — landing on deck or hovering. In either case put the ship on a heading and speed that create a 15 to 25 knot relative wind on one bow. This gives the helicopter a headwind, minimizes the turbulence the superstructure would cause if the wind were dead ahead, and carries the stack gases clear of the approach.
14.1 Relative Wind and Safe Conditions
It is the relative wind that matters, and a maneuvering-board plot may be needed to find the heading that produces it, especially when the true wind exceeds 25 knots. Establish VHF communication early so maneuvers can be agreed; the helicopter pilot may recommend course and speed changes. When the ship is rolling more than a few degrees and the helicopter is to land, the master must warn it off, as landing is then dangerous; hovering is not a problem.
14.2 Deck Preparation
Do not touch a basket or litter until it lands and discharges any static charge. While loading a person or gear into the basket, do not secure it to the ship in any way.