SEAMANSHIP : SEAMANSHIP MT101P LEADERSHIP : LEADERSHIP Leadership : Leadership “Be the kind of leader others want to follow
The key to becoming an effective leader is not to focus on making other people follow, but on making yourself the kind of person they want to follow…”
John Maxwell Slide 4: To ensure safety at sea, the best that science can devise and that the seafaring industry can provide must be regarded only as an aid, and never as a substitute for good seamanship,self-reliance, and sense of ultimate responsibility which are the first requisites in a seaman…
ADM C.W. Nimitz .. 13 February 1945 Seamanship : Seamanship Defined as the work of a seaman on board the ship.
Involves a knowledge of a variety of topics and development of specialised skills including:
navigation and international maritime law;
weather, meteorology and forecasting;
ship-handling and small boat handling;
operation of deck equipment, anchors and cables Slide 6: ropework and line handling;
execution of evolutions such as towing; cargo handling equipment, dangerous cargoes and cargo storage;
dealing with emergencies;
survival at sea and
search and rescue;
fire fighting. Seamanship : Seamanship The most experienced sailor cannot hope to learn everything about it in one lifetime.
Good seamanship embodies thorough knowledge, and intelligent application, of all the principles of operating a ship away from her pier or mooring—getting underway, safety practices, piloting, maneuvering in difficult situations, avoidance of hazards, and so on—plus the constant exercise of prudence, good judgment, and consideration toward others. Slide 8: The highest order of seamanship is practiced by sailors who know what to do after things have gone wrong.
They have anticipated possible trouble, and have given thought to how to handle it.
Good seamanship doesn’t end with handling your own ship.
Knowing how other vessels react in certain situations may be just as important in avoiding collisions and making prudent decisions. Slide 9: Good seamanship starts in port, with detailed preparation and careful checks—and it never ends. LOADLINES 11 : LOADLINES 11 Loadlines : Loadlines Loadlines : Loadlines Slide 13: LTF = Tropical Fresh Water Timber Loadline
LF = Fresh Water Timber Loadline
LT = Tropical Timber Loadline
LS = Summer Timber Loadline
LW = Winter Timber Loadline
LWNA = Winter North Atlantic Timber
Loadline Slide 14: TF = Tropical Fresh water Loadline
F = Fresh Water Loadline
T = Tropical Loadline
S = Summer Loadline
W = Winter Loadline
WNA = Winter North Atlantic Loadline Slide 15: The Maximum depth to which a ship may be loaded in relation to a Timber load shall be the depth indicated by the upper edge of the appropriate Timber Loadline
(Q) What is the purpose of the Summer/winter loadline on a Merchant Navy vessel? Slide 16: (a) For the safety of the crew also, the density of water changes from port to port all around the world, some ports have fresh water coming from rivers, you need to know the density of the water in the harbour using a hydrometer. (Fresh water is 1.000t per metre cubed and sea water is 1.025t per metre cubed) Slide 17: Remember salt water makes your vessel more buoyant, but coming form salt water to fresh water, your vessel is going to sink because fresh water is less buoyant. Slide 19: The Plimsoll Line was painted on the side of merchant ships. When a ship was loaded, the water level was not to go above the line.
However, the water could reach different parts of the line (see drawing) as its temperature and saltiness varied with season and location. Slide 20: The basic symbol, of a circle with a horizontal line passing through its centre, is now recognized worldwide. Slide 21: The loadline and Plimsoll marks are placed amidships on both sides of the hull of a vessel to denote the maximum mean draft to which a vessel may be lawfully submerged for a particular voyage, depending on the area to be traveled and the season of the year. Slide 22: Figure 7-2. Loadline marks. Loadline marks. Slide 23: Loadline markings are used with the Plimsoll mark to indicate the maximum permissible draft of the ship (maximum mean draft to which a vessel may be lawfully submerged for a particular voyage )in different circumstances and seasons. Slide 24: (a) The summer loadline is indicated by the upper edge of line marked S.
(b) The winter loadline is indicated by the upper edge of line marked W.
(c) The winter North Atlantic loadline is indicated by the upper edge of a line marked WNA
(d) The tropical loadline is indicated by the upper edge of a line marked Slide 25: (e) The freshwater loadline in summer is marked by the upper edge of a line marked F.
The difference between the freshwater loadline in summer and the summer loadline is the allowance made for loading in freshwater at the other loadlines. Slide 26: The tropical freshwater loadline is indicated by the upper edge of a line marked TF.
Main deckline. The main deckline mark is a line 12 inches long and 1 inch wide located on each side of the hull amidships directly opposite the main deck plating and directly over the loadline. Slide 27: SHIP MEASUREMENT Slide 28: Length
Length overall · Length between perpendiculars · Length at the waterline
Beam Slide 29: Depth
Draft · Moulded depth · Freeboard · Waterline (Plimsoll Line)
Worldwide : Tonnage · Gross tonnage · Net
Specialized: Panama Canal/Universal Measurement
Archaic: Gross Register Tonnage · Net register
tonnage Slide 30: Capacity
Deadweight tonnage · Twenty-foot equivalent unit
Displacement · Loaded Displacement · Standard Displacement · Light Displacement · Normal displacement Slide 31: Stability
Inclining test · List · Angle of loll · Metacentric height (GM)
Aframax · Capesize · Chinamax · Handymax/Supramax · Handysize · Malaccamax · Panamax and New Panamax · Seawaymax
· Suezmax · VLCC and ULCC Length Overall : Length Overall Length Overall abbreviated as (LOA, o/a, o.a. or oa) refers to the maximum length of a vessel from the two points on the hull measured perpendicular to the waterline.
Used to indicate maximum length of a vessel. Slide 34: p/p = length between perpendiculars w/l = length at waterline o/a = length overall b = beam f = freeboard d = draft Length Between Perpendiculars : Length Between Perpendiculars Length between perpendiculars, (a.k.a. p/p, p.p., pp, LPP, LBP or Length BPP is a term describing the length of a ship.
LBP refers to the length of a vessel along the waterline from the forward surface of the stem, or main bow perpendicular member, to the after surface of the sternpost, or main stern perpendicular member. Width : Width A ship’s width or, more properly, a ship’s breadth is expressed in a number of ways and, like length, for a number of reasons.
A ship’s extreme breadth, commonly called beam, is measured in feet and inches from the most outboard point on one side to the most outboard point on the other at the widest point on the ship. Width : Width Beam (B). The beam of a ship is its width at the widest point. (ex: BWL is the maximum beam at the waterline)
The transverse distance between the moulded or inboard surfaces of the side shell plating measured at the widest portion of a ship's hull; used in calculation. Slide 40: Extreme Breadth
The transverse distance extending from the most outboard point on one side to the most outboard point on the other side of a ship's hull including any projections on the ship's side; this dimension determines the maximum space occupied by the ship when used with length overall DEPTH : DEPTH DEPTH ---- The height of the ship ar the midship section from the base line to the moulded line of the deck at side (underneath). T he vertical distance from the bottom of the hull to the uppermost edge at the side.
DRAFT (d) or (T). Draft is the vertical distance measured from the keel (lowest part of the hull) to the waterline Slide 43: DRAFT (Moulded) ---- The height from the base line to the load water line.
Draft marks are numbers placed on the bow and stern to indicate the amount of water a vessel draws. Slide 44: Various Draft Readings Slide 45: Mean Draft.
Mean draft is the average of the drafts measured at bow and stern. For example, if the draft forward is 26 feet and the draft aft is 27 feet 6 inches, the sum of the two readings is 53 feet 6 inches. Dividing the sum by 2 gives a mean draft of 26 feet and 9 inches. Slide 46: Freeboard. Freeboard (FB) is the difference between Depth and draft. Freeboard is the measured vertical distance amidships from the upper edge of the main deck line amidships to the upper edge of the water (related load line). Slide 47: Statutory Freeboard – the vertical distance from the top edge of a line (DECK LINE painted at mid-length on the ship’s sides which marks the freeboard deck.
Freeboard Deck it is the uppermost complete deck exposed to weather and sea, which as permanent means of closing all openings in the weather. EMPLOYMENT OF SHIPS : EMPLOYMENT OF SHIPS LINERS - Vessels whose trades are according to schedule between two or more designated and definite ports.
TRAMPS - Trading in areas where its services are needed to transport cargo or where the market takes it. VOLUME : VOLUME TONNAGES
The tonnage of ships is determined in several different ways; it may be a measurement of either (1) weight, or (2) size without regard to weight (volume). TWO KINDS OF TONNAGE FIGURES : TWO KINDS OF TONNAGE FIGURES 1. RELATED TO WEIGHT ACTUAL TONS (2,240 LBS OR TONNES OF 1,000 KILOGRAMS).
LlGHT DISPLACEMENT - The weight of the ship’s structure when completely empty of all bunkers, stores and cargo.
LOAD DISPLACEMENT – The weight of the ship when loaded to the depth of her seasonal loadline Slide 52: DEADWEIGHTCARRYING CAPACITY The deadweight capacity of the vessel available for cargo. (i.e DWT less weight of fuel bunkers, water and stores, lubricants and spares on board When loaded to Tropical Summer and Winter Loadline respectively.
DEADWEIGHT – As some particular mean draught. The difference between Load and Light Displacement, i.e. Slide 53: TROPICAL DEADWEIGHT The difference between the Light Displacement and the Displacement when submerged in sea water to the depth of the tropical load line. SUMMER DEADWEIGHT, WINTER DEADWEIGHT AND THE DEADWEIGHTS AT OTHER ASSIGNED LOADLINES MAY BE DEFINED SIMILARLY RELATED TO MEASUREMENT : RELATED TO MEASUREMENT - GROSS REGISTERED TONNAGE (GRT) - The total internal volume of a ship (100 cu. ft = 1 Ton) and is equal to the UNDER DECK TONNAGE PLUS THE TONNAGE OF ALL ENCLOSED SPACES ABOVE THE TONNAGE DECK. . Tonnage Measurement : Tonnage Measurement GROSS TONNAGE (GT)
Is the capacity of the spaces in the ship's hull and of the enclosed spaces above the deck available for cargo, stores, fuel, passengers, and crew. Slide 56: NET TONNAGE(NT)
The earning capacity of a vessel. It is based on a calculation of the volume of all cargo spaces of the ship. It indicates a vessel’s earning space and is a function of the moulded volume of all cargo spaces of the ship. Slide 57: - DEADWEIGHT TONNAGE (DWT) - Maximum total weight of stores, bunkers, water, cargoes which the vessel can lift on her summer loadline.
- DISPLACEMENT- The actual total weight of the vessel expressed in long tons or in metric tons. It is the mass of the ship and everything it contains is equal to Deadweight + Lightweight Slide 58: - PANAMA CANAL TONNAGE - The Panama Canal/Universal Measurement System (PC/UMS) is based on net tonnage, modified for Panama Canal purposes. PC/UMS is based on a mathematical formula to calculate BALE AND GRAIN CAPACITY : BALE AND GRAIN CAPACITY Bale Cubic Capacity.
Bale cubic capacity, a measure of the ship’s internal volume of cargo holds, is the space available for loading cargo measured in cubic feet extending to the inside of the cargo battens on the frames and to the underside of the beams. Used to compute the space available for general cargo. Slide 60: The cubic capacity of a cargo is the maximum space available for cargo, measured from the inside of of the cargo battens, frames, bulkheadstiffeners or spar ceilings.
The bale capacity is generally less than the hold's grain capacity; sometimes known as bale cubic Slide 61: Grain Cubic Capacity.
Grain cubic capacity is measured in cubic feet from the inside of the shell plating to the underside of the deck plating. This measurement is used for computing cubic space available for loading bulk commodities. sometimes known as Grain Cubic. Slide 62: The volume in cubic feet or cubic metres is a measure of two types of cargo, bulk or small particles ("grain") and bags or packaged cargo ("bale"). Slide 63: Ship Structural Elements - Construction of Ships BASIC DEFINITONS AND SHIP GEOMETRY : BASIC DEFINITONS AND SHIP GEOMETRY Figure illustrates the main parts of a typical ship. Slide 66: Forward Perpendicular (FP) : The vertical line at the point of intersection of the LWL and the forward end of the immersed part of the ship’s hull.
After Perpendicular (AP) : The vertical line at the point of intersection of the LWL and the centerline of the rudderstock.
Midships () : The point midway between the forward and after perpendiculars. Slide 67: Trim : The difference between the draughts forward and aft.
Depth Moulded (D) : The vertical distance at amidships from the baseline to the underside of the plating of the main deck.
Freeboard (f) : The vertical distance from the waterline to the deck at side. The freeboard is equal to the difference between the depth at side and the draught at any point along the ship. Slide 68: Moulded Displacement : The displacement of a ship based on moulded dimensions
Total Displacement : Moulded displacement modified by adding the thickness of shell plating and the volume of appendages.
Wetted Surface : The area of the underwater hull and appendages, measured in square meters. Slide 69: Port :The left side of the ship when looking forward
Starboard : The right side of the ship when looking forward
Design Waterline (DWL) or Load Waterline (LWL) : The waterline at which the ship will float when loaded to its designed draught.
Moulded Surface : The inside surface of the skin, or plating, of a ship. Slide 70: Five regions of the ship stern, bow, engine region, cargo region and super structure. Hull : Hull Two main methods that are used for hull construction : Two main methods that are used for hull construction Transverse framing
Longitudinal framing. Hull : Hull The HULL is the main body of the ship that floats on the water.
In order to provide the maximum space to store cargo, the hull is constructed with a rectangular cross section. Ship hull structure elements : Ship hull structure elements Slide 77: Deck plating (a.k.a. Main Deck, Weatherdeck or Strength Deck)
Inner bottom shell plating
Hull bottom shell plating
Transverse frame (1 of 2)
Keelson (1 of 4)
Longitudinal stiffener (1 of 18)
Hull side beam Slide 78: Shell plating is the outer-most structure on the hull of a steel or aluminum ship or boat. It is the structural element that renders the hull watertight. Strakes : Strakes A strake refers to the longitudinal run of plating covering the hull, deck and bulkhead structure. Certain specific strakes are uniquely identified:
Keel : is a special strake of the Bottom plating extending from the centerplane outboard.
Bottom : the Bottom Shell plate strakes extend from the Keel to the Bilge. Slide 81: Bilge : is the plating which transitions from the more-or-less horizontal Bottom Shell to the more-or-less vertical Side Shell and is generally curved.
Side : is the plating which extends from the Bilge stake(s) to the Shear strake.
Shear : is a special strake of the Side plating. It is the strake that connects the Side Shell to the Strength Deck. Slide 82: Stringer : is a special strake of the Strength Deck plating. It is the strake that connects the Strength Deck to the Side Shell.
Strength Deck : is a special deck. It is normally the uppermost continuous deck and forms the top flange of the hull girder. Slide 83: The KEEL is the fore and aft centerline of the ship.
The backbone of the ship, the keel is the skeleton of the ship's hull.
Other portions like the corner edges (bilge keels, sheerstrake) are also strengthened Slide 84: The KEEL is the fore and aft center line of the ship. The backbone of the ship, the keel is the skeleton of the ship's hull.
Other portions like the corner edges (bilge keels, sheerstrake) are also strengthened .
A major component providing longitudinal strength and efficiently distributes local stresses when the ship is dry docked. Types of Keel : Types of Keel flat keel Slide 86: Other portions like the corner edges (bilge keels, sheerstrake) are also strengthened.
In order to float, the steel ship must have a large volume compared to the weight. The steel plates (about 10 mm thick) will not be able to resist the buoyancy forces on their own. Bilge keel : Bilge keel Slide 88: A bilge keel is a long fin of metal, often in a "V" shape, welded along the length of the ship at the turn of the bilge.
Employed in pairs (one for each side of the ship).
Increase the hydrodynamic resistance when a vessel rolls, and limits the amount of roll a vessel has to endure. Slide 92: A double bottom is a ship hull design and construction method where the bottom of the ship has two complete layers of watertight hull surface:
one outer layer forming the normal hull of the ship, and a second inner hull which is somewhat higher in the ship, perhaps a few feet, which forms a redundant barrier to seawater in case the outer hull is damaged and leaks Slide 95: Frames are used to support the steel plates.
Frames are the RIBS of the ships.
Some ships are framed horizontally, while others are framed transversely.
At high loading areas the frames are enlarged. These are called web frames. Slide 96: The lower portions of the hull are made stronger in order to cater for the higher loads (pressure) on the hull deeper underwater. Slide 97: The bottom of the hull is made into tanks for fuel oil, fresh water, and ballast seawater.
These are called double bottom tanks. This type of construction reduces the chance of flooding of the ship in case of any damage to the outer hull plates Slide 98: In case of heavy damage which puncture even the tank top plates, the ship is prevented from sinking by bulkheads. Bulkheads are continuous walls that divide the ship into many sections.
The purpose of these bulkheads is to isolate the flooded sections from the rest of the ship. EXTERNAL PARTS OF THE HULL : EXTERNAL PARTS OF THE HULL SHELL PLATING - SKIN : SHELL PLATING - SKIN The skin, or shell plating, provides water-tightness.
The plates, as principal strength members of a ship, have various thickness. The heaviest plates are put on amidships.
The plates, put on in rows from bow to stern, are called strakes. STRAKE NAMES : STRAKE NAMES Garboard strakes - the bottom row of strakes on either side of the keel.
Bilge strakes - the strakes at the turn of the hull, running in the bilge.
Bottom strakes - the strakes running between the garboard and bilge strakes. Slide 102: Sheer strakes - Topmost strakes of the hull. The upper edge of the sheer strake is the gunwale. BULKHEADS : BULKHEADS The interior of the ship is divided by the bulkheads (SHIP’S WALLS) and decks into watertight compartments.
In case of heavy damage which puncture even the tank top plates, the ship is prevented from sinking by bulkheads. Bulkheads are continuous walls that divide the ship into many sections Slide 104: BULKHEADS Bow : Bow The front of the ship is called the bow. It is wedge shaped.
Some ship bows have a spherical shape at the submerged portion. These are called bulbous bows and gives better efficiency to the ship by streamlining the wave flow.
The inside the bow contains the anchor chain and the forepeak tank. Slide 109: Bulbous Bow Stern : Stern The back portion of the ship is called the stern. It contains the propeller, propeller shaft, stern tube, and the rudder.
The propeller acts like a screw when it turns in the water and is rotated at low speeds of 100 to 150 rpm, so that the water can flow smoothly through the blades. Slide 112: The main engine through the shafting inside the engine room rotates the propeller.
The propeller shaft is the shaft that is fitted with the propeller at one end and coupled to the main engine shafting at the other. Slide 113: The propeller shaft rotates inside the oil lubricated stern tube, fitted with bearings. Seawater is prevented from entering the tube by the stern tube seals. Older ships have shaft gland packing and lignum vitae bearings that are lubricated by the seawater. Engine Room : Engine Room The engine room houses all the ship’s machinery for the propulsion of the ship.
If the shafting connecting the main engine to the propeller is long, there will be a shaft tunnel joining the engine room to the stern tube. Slide 115: If the shafting connecting the main engine to the propeller is long, there will be a shaft tunnel joining the engine room to the stern tube. Slide 116: The engine room has at least two escape routes. In case of fire, flooding or any other disaster, the engine room personnel can escape through any one of them.
The engine room doors, skylight, ventilation ducts can be sealed tight if there is a major fire in the engine room Accommodation : Accommodation This portion of the ship is usually painted a different color from the hull. Portholes are visible whenever there is a cabin. The accommodation of the crew can also be part of the hull. Slide 119: The bridge is the highest level on the ship.
The lifeboats are usually located one level above the main deck.
In addition, there will be life rafts on this deck and some on the bridge deck. CARGO HOLD : CARGO HOLD Cargo holds are spaces for carrying dry cargo. Each cargo hold is covered by a hatch cover, which can be opened for cargo handling, and closed when the ship is underway SHIP STRESSES : SHIP STRESSES Slide 124: Shear force and bending moments Slide 125: When a section such as a beam is carrying a load there is a tendency for some parts to be pushed upwards and for other parts to move downwards, this tendency is termed Shearing.
The Shear force at a point or station is the vertical force at that point. TYPES OF STRESSES : TYPES OF STRESSES SHEAR
The effect of forces acting in different directions along a parallel line. Causes the various parts of the vessel to slide on the other. Shear : Shear SHIP STRESS : SHIP STRESS Tension Compression Shear Torsion Slide 129: . Tension TYPES OF STRESSES
TENSILE STRESS – forces in such a direction to increase the length or pulling the material apart Tension : Tension Slide 131: COMPRESSIVE STRESS
Forces acting in a direction to decrease the length or to compress Compression Compression : Compression Slide 133: The longitudinal stresses imposed by the weight and buoyancy distribution may give rise to longitudinal shearing stresses.
The maximum shearing stress occurs at the neutral axis and a minimum at the deck and keel.
Vertical shearing stresses may also occur. Bending Moment : Bending Moment The beam would also have a tendency to bend and the size of the bending moment depends upon the amount of the load as well as how the load is placed together with the method of support Static stresses and constraints : Static stresses and constraints These stresses are measured when the ship is not under way.
They are often caused by a poor longitudinal distribution of mass.
Even if the ship's total weight is balanced by the total force of buoyancy, these forces may not be distributed evenly along the full length of the ship. STRAIN : STRAIN Distortion resulting from stress
Usually expressed in inches/inch STRAIN Hogging and sagging : Hogging and sagging Hogging:
If the forces of buoyancy are concentrated around the section amidships and the ends are loaded, the ship will tend to move downwards at the bow and stern while the section amidships will tend to move upwards SAGGING : SAGGING Deck under compression
Neutral axis experiences no stresses
Keel under tension Slide 141: Sagging:
If the forces of buoyancy are concentrated under the bow and stern of the ship and the section amidships is loaded, the ship will tend to move upwards at the ends and trough amidships
In a seaway the hogging and the sagging stresses are amplified when riding the crests and falling into the troughs HOGGING : HOGGING Deck under tension
Neutral axis experiences no stress
Keel under compression TRANSVERSE BENDING : TRANSVERSE BENDING RACKING – Due to wave action or rolling from one side to the other in a seaway. The different areas of the ship have motion which are dependent on the nature of the subject area. Tank corners may be stressed.(Tank side brackets,Beam knees must be strong.) Ships structure are liable to cause distortion in the transverse section. Dynamic stresses and constraints : Dynamic stresses and constraints Local Stresses
When a ship is under way, some situations create additional stresses. They are caused primarily by the effect of waves on the hull in rough seas.
Two of these are pounding and panting. Slide 147: Panting
A stress, which occurs at the ends of a vessel due to variations in water pressure on the shell plating as the vessel pitches in a seaway.
The bow is most subjected to this pressure when making headway. Slide 149: Pounding
When a ship sails in heavy seas, it pitches.
It can happen that the bow rises over the crest of a wave and emerges completely out of the water.
When the bow comes back down on the water, it can be subjected to a major impact, which is pounding. Stresses caused by localized loading : Stresses caused by localized loading Localized heavy loads may give rise to localized distortion of the transverse section.
Such local loads may be the machinery (Main engine) in the engine room or the loading of concentrated ore in the holds Water pressure and Thrust : Water pressure and Thrust Pressure is force per unit area and water pressure is dependent on the head of the water column affecting the point of the measurement of the pressure. SHIP MOVEMENTS : SHIP MOVEMENTS Ship Movement at Sea : Ship Movement at Sea Ship movements may be divided into Linear motion and Rotational motion
Surging is motion along the longitudinal axis.
Swaying is motion along the transverse axis.
Heaving is motion along the vertical axis. Slide 156: Examples of insufficient attention paid to vessel’s stability and strength during cargo and ballast operation that may bring catastrophic results.
Ship could be swamped in heavy seas.
Can cargo shifting, risk to structural damage. Could lead to vessel capsizing.
Stressed and strained – may suffer structural damages. Slide 157: 4. Incorrect cargo calculation – may lead to ship grounding or nay not sail because the loadline depends on the requirement.
HEELING – due to the external forces: waves, winds, etc.
LISTING – due to the internal factors: cargo shifting, etc. IMPORTANCE OF STRESS : IMPORTANCE OF STRESS Important especially in cargo loading / ballasting operation to avoid sea accidents or mishaps brought about by:
A vessel stressed and strained by excessive bending moments or shear forces could cause. Structural Failure IMPORTANCE OF STRESS : IMPORTANCE OF STRESS b. Uneven distribution of weights throughout the ship or the uneven distribution of buoyancy of the ship in large waves.
c. Uneven loading throughout the length of the ship varies considerably with the different conditions of loading leading to longitudinal bending moments to reach high values. Slide 160: Stress Concentration
A large local increase of stress when a section is under load, 2 or 3 times the average stress elsewhere. Could cause cracks on steel, particularly the welded portions. Slide 161: Ship to be designed carefully as:
to keep concentration to a minimum
to round off and strengthen opening corners,
keep plates and hole edges smooth and free from notches. Slide 162: B. Still Water Bending
A loaded vessel lying in still water, the upthrust at any one meter length of the ship depends upon the immersed cross sectional area of the ship at that point. If the values of the upthrust at different positions along the length of the ship is plotted, a buoyancy curve is formed. Slide 163: Load Distribution Buoyancy Load Bending Moment Shearing Force Weight Slide 164: The area of this curve represents the total upthrust exerted by the water on the ship. With the total weight of the ship known, a curve of weights is plotted.
The difference between the weight and buoyancy at any point is the load at that point. A load diagram is formed by these differences. Slide 165: Since total weight is equal to total buoyancy, the area of the load diagram above the baseline should be equal to that below the baseline.
Due to unequal loading, shearing forces and bending moments are set up on the ship. The maximum bending moment occurs about midships. Slide 166: Depending on the direction on which the bending moment acts, the vessel will hog or sag. Slide 167: Ship movement at sea Slide 168: Ship movement at sea Slide 169: Rotational motion
Rolling is motion around the longitudinal axis.
Pitching is motion around the transverse axis.
Yawing is motion around the vertical axis. Slide 170: Yawing involves rotation of the ship around its vertical axis. This occurs due to the impossibility of steering a ship on an absolutely straight course.
Depending upon sea conditions and rudder deflection, the ship will swing around its projected course. Yawing is not a cause of shipping damage Slide 171: Yawing is motion around the ship's vertical axis Slide 172: Heaving involves upward and downward
acceleration of ships along their vertical axis.
Buoyancy varies as a ship travels through wave crests and troughs. If the wave troughs predominate, buoyancy falls and the ship "sinks" (top picture), while if the wave crests predominate, the ship "rises”. Slide 173: Heaving is motion along the ship's vertical axis Slide 174: In SURGING and SWAYING, the sea's motion accelerates and decelerates the ship forward and backward and side to side. Depending upon the lie of the vessel, these movements may occur in all possible axes, not merely, for example, horizontally. Slide 175: If a vessel's fore-body is on one side of a wave crest and the after-body on the other side, the hull may be subjected to considerable torsion forces Slide 176: Surging is motion along the ship's longitudinal axis Swaying is motion along the ship's transverse axis Slide 177: In PITCHING a ship is lifted at the bow and lowered at the stern and vice versa. Pitching angles vary with the length of vessel.
In relatively short vessels they are 5° - 8° and sometimes more, while in very long vessels they are usually less than 5°. Slide 178: Pitching is the movement of a ship around its transverse axis Slide 179: ROLLING involves side-to-side movement of the vessel. The rolling period is defined as the time taken for a full rolling oscillation from the horizontal to the left, back to horizontal then to the right and then back to horizontal. In vessels with a high righting capacity, i.e. stiff ships, rolling periods of ten seconds and below are entirely usual. Slide 180: In vessels with a high righting capacity, i.e. stiff ships, rolling periods of ten seconds and below are entirely usual. Slide 181: Rolling is the movement of a ship around its longitudinal axis, the rolling angle in this case being 10°. Slide 182: Rolling is the movement of a ship around its longitudinal axis, the rolling angle in this case being 10°. Slide 183: Rolling angle of 45° Slide 184: SLAMMING is the term used to describe the hydrodynamic impacts which a ship
encounters due to the up and down motion of the hull, entry into wave crests and the consequent abrupt immersion of the ship into the sea Slide 185: Slamming describes the hydrodynamic impacts undergone by a ship Slide 186: Free surfaces on board always increase the risk of capsize. Ground Tackle and Mooring Equipment : Cleat - Consists of a double-ended pair of horns, used for securing a line or wire.
Bitts - Pairs of heavy vertical cylinders, used for making fast lines led through chocks.
Bollard - Strong cylindrical upright on a pier, about which a mooring line is placed. Ground Tackle and Mooring Equipment BITTS : BITTS Used to moor large vessels.
Normally found on commercial piers. Ground Tackle and Mooring Equipment : Ground Tackle and Mooring Equipment Chock - Heavy fitting with smooth surfaces
through which mooring lines are led. Roller Open Closed CLEAT : CLEAT Found on boats and docks of all sizes.
Used to secure lines of all sizes and uses Ground Tackle and Mooring Equipment : Camel - A large float or raft used as a fender.
Rat guards - Shields secured around mooring lines to prevent rats from coming board ships. Ground Tackle and Mooring Equipment Ground Tackle and Mooring Equipment : Chafing gear - Canvas or other material placed around mooring lines to prevent wear.
Fenders - Material designed to absorb the shock of contact between two ships or a ship and a pier. Ground Tackle and Mooring Equipment Ground Tackle and Mooring Equipment : Padeye - A metal plate with an “eye”, attached to the deck to distribute a load over a large area.
Lifelines - Lines erected around the edges
of decks, referred to as follows:
Top - Lifeline
Middle - Housing line
Bottom - Foot rope
Snaking - Netting rigged
between foot rope and deck. Ground Tackle and Mooring Equipment Ground Tackle and Mooring Equipment : Capstan - Separate vertical machinery units or part of the anchor windlass around which lines are passed, commonly used in mooring and anchoring evolutions. Ground Tackle and Mooring Equipment Slide 196: CRUCIFORM
BOLLARD Dip the Eye : Dip the Eye When two bights are placed on the same bollard, the second one is led up through the first before being put over the bollard. This allows either to be cast off without moving the other. SHIP’S MOORING EQUIPMENT : MOORING LINES
ARE LINES USED TO SECURE THE SHIP TO A BERTH (PIER,WHARF OR ANOTHER SHIP.
MUST BE LIGHT AS POSSIBLE FOR EASY HANDLING ,
STRONG ENOUGH TO TAKE CONSIDERABLE STRAIN WHEN COMING ALONGSIDE AND HOLD THE SHIP TO PLACE WHEN SECURED. SHIP’S MOORING EQUIPMENT Slide 199: KINDS OF MOORING LINE
BOWLINE - LINE THAT RUNS THROUGH THE CHOCK ON THE BOW.
STERN LINE – LINE THAT RUNS THROUGH THE CHOCK ON THE STERN. THESE LINES SHOULD REDUCE THE FORE AND AT MOTION OF THE SHIP Slide 200: BREAST LINE - RUN AT RIGHT ANGLE TO THE KEEL – CALLED BOW BREAST OR QUARTER BREASTS OR SPRINGS. THEY PREVENT SHIP FROM MOVING AWAY FROM THE PIER.
SPRING LINES - LEADS FORWARD AWAY FROM THE SHIP AT AN ANGLE WITH THE KEEL CALLED FORWARD (BOW, WAIST OR BREAST) SPRINGS. THEY PREVENT VESSEL FROM MOVING AFT OR FORWARD . Slide 201: TWO SPRING LINES HEADING IN THE OPPOSITE DIRECTIONS IN THE SAME VICINITY ACT AS BREASTLINES FROM THE PIER TO THE SHIP. MOORING AND UNMOORING : MOORING AND UNMOORING CAPSTAN AND WINCHES - MACHINES USED FOR MOORING /UNMOORING
A CAPSTAN’S TURN AXIS IS HORIZONTAL. THEY ARE DRIVEN BY ELECTRIC OR HYDRAULIC POWER. ALSO USED FOR CARGO HANDLING AND RECOVERING LIFEBOATS AND DAVIT ARMS. Slide 203: WINDLASS – USED TO HOIST THE ANCHOR CHAIN TO HEAVE UP THE ANCHOR.
BITTS - MOORING LINES ARE MADE FAST ON DECKS USING BITTS. ONCE HEAVED IN TIGHT, THEY ARE STOPPERED OFF AND THE MOORING LINE IS TAKEN TO THE BITT. Slide 204: CLEATS AND LUGS - ARE OTHER AIDS FOR BERTHING AND MAY ALSO BE AVAILABLE FOR CARGO WORK.
STOPPER - USED TO TAKE THE WEIGHT OFF ON THE LINE SO THAT IT COULD BE TRANSFERRED TO THE BITTS OR DECK LUGS. Slide 205: BOLLARD -
A FIXTURE ON THE PIER, DOCK OR WHARF USED TO SECURE THE SHIP’S MOORING LINES ASHORE. THE EYE OF THE MOORING LINE IS PASSED OVER THE BOLLARD AND WHEN DONE THE SHIP’S CAPSTANS OR WINCHES STARTS TAKING IN THE LINE ON BOARD. Slide 206: BOLLARD -
A FIXTURE ON THE PIER, DOCK OR WHARF USED TO SECURE THE SHIP’S MOORING LINES ASHORE. THE EYE OF THE MOORING LINE IS PASSED OVER THE BOLLARD AND WHEN DONE THE SHIP’S CAPSTANS OR WINCHES STARTS TAKING IN THE LINE ON BOARD. Mooring Lines : Mooring Lines Mooring lines are the lines used to secure the
ship to a wharf, pier or another ship.
Definition of lines:
Breast lines - Run at right angles from the ship,
control distance of ship from pier
Aft spring lines - Tend aft from ship, control
Forward spring lines - Tend forward from the
ship, control aft movement Mooring Lines : Mooring Lines Numbering of lines:
#1 - Bow line
#2 - Aft bow spring line
#3 - Forward bow spring line
#4 - Aft quarter spring line
#5 - Forward quarter spring line
#6 - Stern line 1 3 4 5 6 2 Mooring Lines : Mooring Lines DO NOT MIX MOORING LINE Never mix lines of different constructions or material . Each type of rope exhibits different elongation characteristics and mixing will result in an unequal load sharing