Jumat, 07 Maret 2014

MARKA DAN DRAFT KAPAL

Load Lines and Draught Marks

Deck line
The deck line is a horizontal line 300 millimetres in length and 25 millimetres in breadth. It shall be marked amidships on each side of the ship, and its upper edge shall normally pass through the point where the continuation outwards of the upper surface of the freeboard deck intersects the outer surface of the shell, provided that the deck line may be placed with reference to another fixed point on the ship on condition that the freeboard is correspondingly corrected. The location of the reference point and the identification of the freeboard deck shall in all cases be indicated on the International Load Line Certificate (1966).
Freeboard. The freeboard assigned is the distance measured vertically downwards amidships from the upper edge of the deck line to the upper edge of the related load line.
Freeboard deck. The freeboard deck is normally the uppermost complete deck exposed to weather and sea, which has permanent means of closing all openings in the weather part thereof, and below which all the openings in the sides of the ship are fitted with permanent means of watertight closing. In a ship having a discontinuous freeboard deck, the lowest line of the exposed deck and the continuation of that line parallel to the upper part of the deck is taken as the freeboard deck. At the option of the owner and subject to the approval of the Administration, a lower deck may be designated as the freeboard deck, provided it is a complete and permanent deck continuous in a fore and aft direction at least between the machinery space and peak bulkheads and continuous athwartships. When this lower deck is stepped the lowest line of the deck and the continuation of that line parallel to the upper part of the deck is taken as the freeboard deck. When a lower deck is designated as the freeboard deck, that part of the hull which extends above the freeboard deck is treated as a superstructure so far as concerns the application of the conditions of assignment and the calculation of freeboard. It is from this deck that the freeboard is calculated.
Load Line Mark
The Load Line Mark shall consist of a ring 300 millimetres in outside diameter and 25 millimetres wide which is intersected by a horizontal line 450 millimetres in length and 25 millimetres in breadth, the upper edge of which passes through the centre of the ring. The centre of the ring shall be placed amidships and at a distance equal to the assigned summer freeboard measured vertically below the upper edge of the deck line.
The Load line rules which were brought in were due to the fact that the ships were being loaded in such a way that the ships were foundering.
Thus the important fact to remember is that it was the freeboard that was being restricted, from very low to a safe figure.
Depending on this freeboard the load line circle was marked as well as the other marks were made for different zones and densities.
Thus the chapter on CONDITIONS OF ASSIGNMENT OF FREEBOARD is very important as it determines as to how much would be the distance between the deck line and the load line circle.
Once this is determined the load line marks are painted, keeping the above in reference.
The calculations give rise to the assigned summer freeboard.
Lines to be used with the Load Line Mark
The lines which indicate the load line assigned in accordance with these Regulations shall be horizontal lines 230 millimetres in length and 25 millimetres in breadth which extend forward of, unless expressly provided otherwise, and at right angles to, a vertical line 25 millimetres in breadth marked at a distance 540 millimetres forward of the centre of the ring.

The following load lines shall be used:
(a) The Summer Load Line indicated by the upper edge of the line which passes through the centre of the ring and also by a line marked S.
(b) The Winter Load Line indicated by the upper edge of a line marked W.
(c) The Winter North Atlantic Load Line indicated by the upper edge of a line marked WNA.
(d) The Tropical Load Line indicated by the upper edge of a line marked T.
(e) The Fresh Water Load Line in summer indicated by the upper edge of a line marked F. The Fresh Water Load Line in summer is marked abaft the vertical line. The difference between the Fresh Water Load Line in summer and the Summer Load Line is the allowance to be made for loading in fresh water at the other load lines.
(f) The Tropical Fresh Water Load Line indicated by the upper edge of a line marked TF, and marked abaft the vertical line.
If timber freeboards are assigned in accordance with these Regulations, the timber load lines shall be marked in addition to ordinary load lines. These lines shall be horizontal lines 230 millimetres in length and 25 millimetres in breadth which extend abaft unless expressly provided otherwise, and are at right angles to, a vertical line 25 millimetres in breadth marked at a distance 540 millimetres abaft the centre of the ring.
The following timber load lines shall be used:
(a) The Summer Timber Load Line indicated by the upper edge of a line marked LS.
(b) The Winter Timber Load Line indicated by the upper edge of a line marked LW.
(c) The Winter North Atlantic Timber Load Line indicated by the upper edge of a line marked LWNA
(d) The Tropical Timber Load Line indicated by the upper edge of a line marked LT.
(e) The Fresh Water Timber Load Line in summer indicated by the upper edge of a line marked LF and marked forward of the vertical line.
The difference between the Fresh Water Timber Load Line in summer and the Summer Timber Load Line is the allowance to be made for loading in fresh water at the other timber load lines.
(f) The Tropical Fresh Water Timber Load Line indicated by the upper edge of a line marked LTF and marked forward of the vertical line.
Where the characteristics of a ship or the nature of the ship’s service or navigational limits make any of the seasonal lines inapplicable, these lines may be omitted.
Where a ship is assigned a greater than minimum freeboard so that the load line is marked at a position corresponding to, or lower than, the lowest seasonal load line assigned at minimum freeboard in accordance with the present Convention, only the Fresh Water Load Line need be marked.
On sailing ships only the Fresh Water Load Line and the Winter North Atlantic Load Line need be marked.
Where a Winter North Atlantic Load Line is identical with the Winter Load Line corresponding to the same vertical line, this load line shall be marked W.
Additional load lines required by other international conventions in force may be marked at right angles to and abaft the vertical line specified in paragraph (1) of this Regulation.
Mark of assigning authority
The mark of the Authority by whom the load lines are assigned may be indicated alongside the load line ring above the horizontal line which passes through the centre of the ring, or above and below it. This mark shall consist of not more than four initials to identify the Authority’s name, each measuring approximately 115 millimetres in height and 75 millimetres in width.
Details of marking
The ring, lines and letters shall be painted in white or yellow on a dark ground or in black on a light ground. They shall also be permanently marked on the sides of the ships to the satisfaction of the Administration. The marks shall be plainly visible and, if necessary, special arrangements shall be made for this purpose.

ZONES, AREAS AND SEASONAL PERIODS
The zones and areas are, in general, based on the following criteria:
Summer - not more than 10 per cent winds of force 8 Beaufort (34 knots) or more.
Tropical - not more than 1 per cent winds of force 8 Beaufort (34 knots) or more. Not more than one tropical storm in 10 years in an area of 5 square in any one separate calendar month.
In certain special areas, for practical reasons, some degree of relaxation has been found acceptable.
Tropical Zone
(1) Northern boundary of the Tropical Zone
The northern boundary of the Tropical Zone is- the parallel of latitude 13N from the east coast of the American continent to longitude 60W, thence the rhumb line to the point latitude 10N longitude 58W, thence the parallel of latitude 10N to longitude 20W, thence the meridian of longitude 20W to latitude 30N and thence the parallel of latitude 30N to the west coast of Africa; from the east coast of Africa the parallel of latitude 8N to longitude 70E, thence the meridian of longitude 70E to latitude 13N, thence the parallel of latitude 13N to the west coast of India; thence the south coast of India to latitude 1030’N on the east coast of India, thence the rhumb line to the point latitude 9N, longitude 82E, thence the meridian of longitude 82E to latitude 8N, thence the parallel of latitude 8N to the west coast of Malaysia, thence the coast of South-East Asia to the east coast of Vietnam at latitude 10N, thence the parallel of latitude 10N to longitude 145E, thence the meridian of longitude 145E to latitude 13N and thence the parallel of latitude 13N to the west coast of the American continent.
Saigon is to be considered as being on the boundary line of the Tropical Zone and the Seasonal Tropical Area.
(2) Southern boundary of the Tropical Zone
The southern boundary of the Tropical Zone is- the rhumb line from the Port of Santos, Brazil, to the point where the meridian of longitude 40W intersects the Tropic of Capricorn; thence the Tropic of Capricorn to the west coast of Africa; from the east coast of Africa the parallel of latitude 20S to the west coast of Madagascar, thence the west and north coasts of Madagascar to longitude 50E, thence the meridian of longitude 50E to latitude 10S, thence the parallel of latitude 10S to longitude 98E, thence the rhumb line to Port Darwin, Australia, thence the coasts of Australia and Wessel Island eastwards to Cape Wessel, thence the parallel of latitude 11S to the west side of Cape York; from the east side of Cape York the parallel of latitude 11S to longitude 150W, thence the rhumb line to the point latitude 26S, longitude 75W, and thence the rhumb line to the west coast of the American continent at latitude 30S.
Coquimbo and Santos are to be considered as being on the boundary line of the Tropical and Summer Zones.
(3) Areas to be included in the Tropical Zone
The following areas are to be treated as included in the Tropical Zone-
(a) The Suez Canal, the Red Sea and the Gulf of Aden, from Port Said to the meridian of longitude 45E.
Aden and Berbera are to be considered as being on the boundary line of the Tropical Zone and the Seasonal Tropical Area.
(b) The Persian Gulf to the meridian of longitude 59E.
(c) The area bounded by the parallel of latitude 22S from the east coast of Australia to the Great Barrier Reef, thence the Great Barrier Reef to latitude 11S. The northern boundary of the area is the southern boundary of the Tropical Zone.
Seasonal Tropical Areas
The following are Seasonal Tropical Areas:
(1) In the North Atlantic
An area bounded-
on the north by the rhumb line from Cape Catoche, Yucatan, to Cape San Antonio, Cuba, the north coast of Cuba to latitude 20N and thence the parallel of latitude 20N to longitude 20W;
on the west by the coast of the American continent;
on the south and east by the northern boundary of the Tropical Zone.
Seasonal periods:
TROPICAL: 1 November to 15 July
SUMMER: 16 July to 31 October.
(2) In the Arabian Sea
An area bounded-
on the west by the coast of Africa, the meridian of longitude 45E in the Gulf of Aden, the coast of South Arabia and the meridian of longitude 59E in the Gulf of Oman;
on the north and east by the coasts of Pakistan and India;
on the south by the northern boundary of the Tropical Zone.

Seasonal periods:
TROPICAL: 1 September to 31 May
SUMMER: 1 June to 31 August.
(3) In the Bay of Bengal
The Bay of Bengal north of the northern boundary of the Tropical Zone.
Seasonal periods:
TROPICAL: 1 December to 30 April
SUMMER: 1 May to 30 November.
(4) In the South Indian Ocean
(a) An area bounded-
on the north and west by the southern boundary of the Tropical Zone and the east coast of Madagascar;
on the south by the parallel of latitude 20S;
on the east by the rhumb line from the point latitude 20S, longitude 50E, to the point latitude 15S, longitude 5130’E, and thence by the meridian of longitude 5130’E to latitude 10S.
Seasonal periods:
TROPICAL: 1 April to 30 November
SUMMER: 1 December to 31 March.
(b) An area bounded-
on the north by the southern boundary of the Tropical Zone;
on the east by the coast of Australia;
on the south by the parallel of latitude 15S from longitude 5130’E, to longitude 120E and thence the meridian of longitude 120E to the coast of Australia;
on the west by the meridian of longitude 5130’E.
Seasonal periods:
TROPICAL: 1 May to 30 November
SUMMER: 1 December to 30 April.
(5) In the China Sea
An area bounded-
on the west and north by the coasts of Vietnam and China from latitude 10N to Hong Kong;
on the east by the rhumb line from Hong Kong to the Port of Sual (Luzon Island) and the west coasts of the Islands of Luzon, Samar and Leyte to latitude 10N;
on the south by the parallel of latitude 10N.
Hong Kong and Sual are to be considered as being on the boundary of the Seasonal Tropical Area and Summer Zone.
Seasonal periods:
TROPICAL: 21 January to 30 April
SUMMER: 1 May to 20 January.
(6) In the North Pacific
(a) An area bounded-
on the north by the parallel of latitude 25N;
on the west by the meridian of longitude 160E;
on the south by the parallel of latitude 13N;
on the east by the meridian of longitude 130W.
Seasonal periods:
TROPICAL: 1 April to 31 October
SUMMER: 1 November to 31 March.
(b) An area bounded-
on the north and east by the west coast of the American continent;
on the west by the meridian of longitude 123W from the coast of the American continent to latitude 33N and by the rhumb line from the point latitude 33N, longitude 123W, to the point latitude 13N, longitude 105W;
on the south by the parallel of latitude 13N.
Seasonal periods:
TROPICAL: 1 March to 30 June and
1 November to 30 November
SUMMER: 1 July to 31 October and
1 December to 28/29 February.
(7) In the South Pacific
(a) The Gulf of Carpentaria south of latitude 11S.
Seasonal periods:
TROPICAL: 1 April to 30 November
SUMMER: 1 December to 31 March.
(b) An area bounded-
on the north and east by the southern boundary of the Tropical Zone;
on the south by the Tropic of Capricorn from the east coast of Australia to longitude 150W, thence by the meridian of longitude 150W to latitude 20S and thence by the parallel of latitude 20S to the point where it intersects the southern boundary of the Tropical Zone;
on the west by the boundaries of the area within the Great Barrier Reef included in the Tropical Zone and by the east coast of Australia.
Seasonal periods:
TROPICAL: 1 April to 30 November
SUMMER: 1 December to 31 March.
Summer Zones
The remaining areas constitute the Summer Zones.
However, for ships of 100 metres (328 feet) and under in length, the area bounded-
on the north and west by the east coast of the United States;
on the east by the meridian of longitude 6830’W from the coast of the United States to latitude 40N and thence by the rhumb line to the point latitude 36N, longitude 73W;
on the south by the parallel of latitude 36N;
is a Winter Seasonal Area.
Seasonal periods:
WINTER: 1 November to 31 March
SUMMER: 1 April to 31 October

Reading Draughts:
The following figure shows the draught marks between 11m and 12m.
It means that the mark is submerged up to the level of the mark, measurement of draught being from the bottom up.
When the water is touching exactly the 11M mark at the bottom, only then is the draught read as 11m. anywhere above that is more than 11m.
The height of the mark being 20cm, therefore the top of the 11m mark would read a draught of 11.20 m.
The bottom of the decimal mark of 2 coincides with the top of the 11M mark and is to be read as 11.20m.
The decimal marks are each 10 cm in height.
Since the decimal marks are at – 2, 4, 5 and 8, the odd numbered decimal being ignored, thus the top of this 2 would read as 30 cm above the 11m mark or 11.30m.
If the water level were at a position between the top of 2 and the bottom of 4 then the reading would be 11.35m.
Rest of the marks are self explanatory.
If reading the draughts in choppy sea condition then the average of at least 5 readings would give a reasonable draught. Note do not read only the highest or the lowest since these may be due to out of the normal waves.
For loading to draught marks – or when being surveyed for load line compliance, the draught may be used to check for overloading or submerging the load line mark. However it should be remembered that it is the freeboard that is being checked.
For load line surveys the surveyor would mark a long baton (wooden) with the total length of the freeboard (summer) and others and then checks with the same against the deck line and the markings on the shipside (midship marks).

LENGKUNGAN STRUKTUR KAPAL (DISTRESS)

Ship Stresses

Shear force and bending moments

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. The shear force at a station may also defined as being the total load on either the left hand side or the right hand side of the station; load being defined as the difference between the down and the upward forces, or for a ship the weight would be the downward force and the buoyancy would be the upward thrust or force.
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
The beam, which we have been considering, would also have a tendency to bend and the bending moment measures this tendency.
Its size depends upon the amount of the load as well as how the load is placed together with the method of support.
Bending moments are calculated in the same way as ordinary moments that is multiplying force by distance, and so they are expressed in weight – length units.
As with the calculation of shear force the bending moment at a station is obtained by considering moments either to the left or to the right of the station.
Hogging and sagging
Hogging – When a beam is loaded or other wise is subjected to external forces such that the beam bends with the ends curving downwards it is termed as hogging stress.
For a ship improper loading as well as in a seaway when riding the crest of a wave the unsupported ends of the ship would have a tendency similar to the beam above.

Sagging – In this case the beam is loaded or other wise subjected to external forces making the beam bend in such a way that the ends curve upwards, this is termed as sagging.
Similar with a ship if improper loaded or when riding the trough of a wave – with crests at both ends then the ship is termed to be sagging.
For Hogging the ship ends to curve downwards would mean that the weight/ load amidships is much less than at the end holds/ tanks.
For Sagging the ship would have been loaded in such a manner that a greater percentage of the load is around the midship area.
In a seaway the hogging and the sagging stresses are amplified when riding the crests and falling into the troughs. Thus especially for large ships there are two conditions in the stability software – Sea Condition and Harbour condition.
A ship loaded while set in the harbour condition may allow loading with hogging/ sagging stresses reaching a high level, when this state of loading is transferred to a Sea condition in the software the results would be catastrophic since now the wave motions have also been incorporated.
Thus planning a loading should always be in the Sea Condition.
Discharging in port may be planned in the Harbour Condition.
Hogging and sagging cause compressive and tensile stresses on the ship beam – notably on the deck and the keel structure.
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.
Let us assume an area of 1sq.m. then this area of water up to a depth of 1 m below the surface would have a volume of 1sq.m. x 1m = 1cbm and the weight of this volume would be 1cbm x density of the water = 1MT (assuming that it is FW) or 1000kgf, therefore the pressure exerted by this mass would be 1000kgf/sq.m.
Similarly if now the depth of measurement is increased to 3m then the volume of this area subtending up to the 3m mark would be 1sq.m x 3 = 3cbm and the weight of the water would be 3MT or 3000kgf and the pressure exerted would be 3000kgf/sq.m.
If now the liquid had not been FW but any other then the weight would be found by multiplying the volume by the density of the liquid. And thus the pressure exerted would be found.
If we now increase the area of the square of water plane would it make a difference in the pressure?
Let us consider a area of 2000sq.m then the volume of this water at a depth of 1 m would be 2000cbm and the weight would be 2000MT (consider FW) and the pressure exerted would be 2000,000kgf/ 2000sq.m which would give us again 1000kgf/sqm, thus the pressure is independent of the area of the water plane.
Thrust however is different, thrust is taken to be the total weight of the liquid over an area. Thus for the previous example the thrust would be 2000 tonnes.
Thus the thrust is given by: the area of the water plane x pressure head x density of the liquid.
Thrust always acts at right angles to the immersed surface and for any depth the thrust in any of the directions is the same. The pressure head which is used in the above calculation of thrust is the depth of the geometrical centre of the area below the surface of the liquid.
For a ship the thrust on the ship side changes as the depth increases, however the bottom is affected uniformly for a set depth.
Centre of pressure of an area is the point on the area where the thrust could be considered to act. It is taken that the centre of pressure is at 2/3rds the depth below the surface for ordinary vertical bulkheads and at half the depth in the case of collision bulkheads.
Racking stress and its causes
In a seaway as a ship rolls from one side to the other the different areas of the ship have motion which are dependent on the nature of the subject area. The accelerations are thus not similar due to the various masses of the different sections (although joined together). These accelerations on the ships structure are liable to cause distortion in the transverse section. The greatest effect is under light ship conditions.

Local Stresses
Panting
This is 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 effect is accentuated at the bow when making headway.
Pounding:
Heavy pitching assisted by heaving as the whole vessel is lifted in a seaway and again as the vessel slams down on the water is known as pounding or slamming. This may subject the forepart to severe blows from the sea. The greatest effect is experienced in the light ship condition.
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.
Shearing force Curve
The following example shown is for an old tanker in the ballast condition.
The compartments loaded are the Fpk tank, WB tanks 2P and 2S, WB tank 3C and other miscellaneous tanks in the after section of the tanker.
The SF is calculated as per the manual with the multipliers having been set by the shipyard and approved by the classification society.
If we are to assume that the ship is a beam then the loads are at the fore end – midship region and the after section which has the accommodation as well as the ER.
The SF curve is reproduced and the maximum occur at frames 54 and between 68 to 72, this corresponds to the area on the ship – mid 4C and between 2C (aft to mid region). Note that the signs have changed between the frames 54 and 68 with a point between frames 59 to 63 (3C mid to aft) registering 0 value.



Bending Moment Curve
The following example shown is for a old tanker in the ballast condition.
The compartments loaded are the Fpk tank, WB tanks 2P and 2S, WB tank 3C and other miscellaneous tanks in the after section of the tanker.
The BM is calculated as per the manual with the multipliers having been set by the shipyard and approved by the classification society.
If we are to assume that the ship is a beam then the loads are at the fore end – midship region and the after section which has the accommodation as well as the ER.
The BM curve is reproduced and the maximum occur at frames 59 and 76, this corresponds to the area on the ship – 4C forward bulkhead and 2C forward bulkhead. Note that the signs have changed twice.



SHIP DIMENSI

Ship Dimensions and Form
General Cargo Vessel
These types of ships in general are built with longitudinal framing at the decks and in the double bottoms. Transverse framing is at the sides.
Profile

The transverse strength is given by fitting transverses at the deck and plate floors are fitted in the double bottoms.
Longitudinal framing is not usual in general cargo vessels due to the high broken stowage involved. Also deep transverses then have to be fitted about 3.7 metres to give the ship transverse strength.
Bilge wells are fitted with a cubic capacity of 0.17 cbm. Nowadays ceiling on top of tank tops are generally not fitted as such the plating is increased by 2mm. However where ceiling is fitted they should be removable in sections. The ceiling where fitted should have a clear space for drainage at least of 12.5mm.
Cargo battens are fitted to the sides and to the turn of the bilges – size of 50mm thick and spacing between rows of 230mm.
Midship
Shown above is a centre line bulkhead in the lower hold and in the tween deck. This extends from the transverse watertight bulkhead to the hatch coamings.
Tankers
These ships may have two or more longitudinal bulkheads – today with double hull concept at least 3 but normally 4.
The bottom and deck are also framed longitudinally and so are the sides and the sides of the longitudinal bulkheads.
The length of a tank is not to exceed 0.2L. As the size of the tanker grows transverse wash bulkhead are fitted at about mid length of the tank. These are for size of tanks over 0.1L or 15m whichever is more.
Centre line was bulk heads are fitted where the breadth exceeds the dimensions as laid out in the Rules for different size of tanks.
Cofferdams are provided both forward of the oil carrying space as well as in from of the ER bulkhead. Generally the pumproom is located within the cofferdam aft. Some ships have a forward pump room located in the forward cofferdam.
The cofferdams are to be at least 760mm in length
Some smaller ships have a combined transverse and longitudinal framing system.
In lieu of bulwarks these ships are to have open rails on deck.
Cargo tanks are tested by a head of water in the cargo tank – 2.45m above the highest point of the tank.
Generally a system of staggered test is undertaken. Alternate tanks are filled and the empty tanks is inspected. Once all the empty tanks are inspected, the filled tanks are empties and the reverse tanks are filled and the other alternates inspected.
Inspecting of the tank welding are done by rafting within a tank.
Profile
Plan
Midship

Bulk Carriers:
These ships are characterised by their ability to carry cargo in bulk. If carrying grain and other lighter cargo all the holds are filled.
However if heavy cargo such as iron ore is carried then alternate holds are filled and to the designed loads only.
Profile
The vessel may be constructed on the combined system, longitudinal framing together with transverse framing which are fitted at the sides. The longitudinal framing is fitted in the double bottoms, the deck and the bottoms of the wing tanks.
The wing tanks may be utilised to carry cargo as well as remain empty. They carry ballast water during the ballast passage.
Transverse webs are fitted at in the wing tanks at intervals as laid out in the Rules. And side stringers are fitted at about 1/3rd and 2/3rd the depth of the tanks.
Plan
Midship

Combination Carriers:
These ships are capable of carrying ore as well as oil in bulk.
Transverse bulkheads are usually of the cofferdam type with all the stiffening on the inside.
There is a rise of floor of the inner bottom which facilitates drainage to the drain well arranged on the centre line. The pipelines run through a duct keel. The duct keep entrance in the pumproom has a oil and gas tight door.
Profile
On the top the hatch covers are mainly the side rolling Macgregor type.
The hatch breadth is usually about 50% of the breadth of the beam. The main disadvantage of this type of ship is the stability – since they are not built with a longitudinal partition in the centre the free surface effect is enormous and this necessitates overall loading complexities.
Plan
Together with this is the sloshing effect which tend to damage the fitting inside.
The stability book would give the loading levels as well as the loading stability requirements as per the Rules.
Midship
Container:
Longitudinal framing is used throughout the main body length of the ship. Transverse framing is used on the fore part and the after part.
Profile
The ships are built having a cellular construction at the sides. Strong longitudinal box girders are formed port and starboard by the upper deck – the second deck – top of the shell plating and top of the longitudinal bulkhead. The upper deck and the sheer strake form the box girder. These girders also provide stiffness against racking stresses and used as water ballast tank spaces.
Midship
A form of bulkhead is fitted at intervals, centre to centre with water tight bulkheads being fitted as required by the Rules. The bulkhead gives support to the double bottom structure.
The container guides consist of angle bars about 150mm x 150mm x 14mm thick connected to vertical webs and adjoining structure spaced 2.6m apart. The bottom of the guides is bolted to brackets welded to the tank top and beams. The brackets are welded to doubling plates, which are welded to the tank top.
Ro – Ro
Roll on Roll off ships have generally two ramps at either end of the ship to facilitate the loading of vehicles.
The main characteristic of these types of ships is the clear decks un interrupted by transverse bulkheads. Deck heights are sufficient to accommodate the various types of vehicles carried.
Profile
The lower decks may be used for carriage of cars while the upper may be used for the carriage of bigger vehicles.
Transverse strength is maintained by fitting deep closely spaced web frames in conjunction with deep beams. These are usually fitted every 4th frame and about 3 m apart.
The lower decks which are divided by watertight bulkheads have hydraulically operated sliding bulkhead doors which are opened while working cargo in port.
The deck thickness is increased to take the concentrated loads; a reduction in the spacing of the longitudinals with an increase in size. A centre line row of pillars is fitted.
Ramps are fitted at the bow and at the stern to facilitate the loading and discharging of vehicles. The separate decks are reached by fixed and sometimes hydraulically operated foldable operated ramps.
A service car is provided within the ship to transfer the lashing gear to the different decks.

Midship
The stern ramps are generally set at an angle to the ships centre line to ensure that the ship can work cargo in any berth.

Passenger:
The basic construction of these vessels follows the dry cargo vessel in their detail, a large number of decks being fitted.
Profile
Each passenger ship is differently built with the naval architects and the classification societies agreeing on the various additions to the various pillars and bulkheads.
However the basic rule and the provisions of SOLAS, MARPOL are complied with.
Midship

Midship in way of ER

Definitions
Camber
The purpose of rounding the beam is to ensure a good drainage of the water and also to strengthen the upper deck and the upper flange of the ship girder against longitudinal bending stresses- especially the compression stresses.
Rise Of Floor
This is the distance from the ‘line of floor’ to the horizontal, measured at the ship side. Purpose basically is to allow drainage of the double bottom water/ oil to the centre line suctions.
Tumblehome
This is the inward slope of the side plating from the water line to the upper deck – today ships generally do not have a tumblehome.
Flare
This is the curvature of the side plating at the forward and gives additional buoyancy and thus helps to prevent the bows from diving too deeply into the water when pitching.
The anchors are also clear when lowered from the flare of a ship.
Sheer
This is the rise of ships deck fore and aft. This again adds buoyancy to the ends where it is needed during pitching. For calculating the freeboard a correction is applied for the sheer. In modern ship the after sheer has been greatly reduced.
Rake
This is the slope, which the forward end has with between the bottom plating and the upper deck. The length between perpendiculars and the length overall difference is mostly due to the rake forward. It helps to cut the water and thus adds to the ships form.
Parallel Middle Body
This is the part of the main body of the ship and it is a box like structure enabling maximum cargo carrying capacity. It also helps in the pushing when tugs are used to assist the vessel in berthing. Cargo stowage is also greatly facilitated.
Entrance
This part is the fore end of the ship and helps give the box like mid length a ship shaped structure.
Run
The after part similarly to the fore part entrance helps in giving the box like mid length a ship shaped structure and thus the handling of the vessel is enhanced.
“Length” means 96 per cent of the total length on a waterline at 85 per cent of the least moulded depth measured from the top of the keel, or the length from the fore side of the stem to the axis of the rudder stock on that waterline, if that be greater. In ships designed with a rake of keel the waterline on which this length is measured shall be parallel to the designed waterline.

Moulded breadth: is the greatest moulded breadth – measured inside plating.
Breadth (B) is the greatest moulded breadth of the ship at or below the deepest subdivision load line.
Draught (d) is the vertical distance from the moulded baseline at midlength to the waterline in question.
Depth and the draught both are measured from the top of the keel. The depth is measure from the top of the deck beam. If there is a camber then allowance is given as 1/3 rd of the camber.
The rest of the meanings are all self-explanatory.


Definitions
Forward perpendicular
This is represented by a line, which is perpendicular to the intersection of the designed load water-line with the forward side of the stem.
After perpendicular
A line represents this, which is perpendicular to the intersection of the after edge of the rudderpost with the designed load water line. This is the case for both single and twin-screw ships. For some ships having no rudderpost, the after perpendicular is taken as the centre-line of the rudderstock.
Length between perpendiculars
This is the horizontal distance between the forward and after perpendiculars.
Length on the designed load waterline
This is the length, as measured on the water-line of the ship when floating in still water in the loaded, or designed, condition.
Length overall
This is the length measured from the extreme point forward to the extreme point aft.
Base line
This represents the lowest extremity of the moulded surface of the ship. At the point where the moulded base line cuts the midship section a horizontal line is drawn, and it is this line, which acts as the datum, or base line, for all hydrostatic calculations. This line may, or may not, be parallel to the load water line depending on the type of ship.
Moulded depth
This is the vertical distance between the moulded base line and the top of the beams of the uppermost continuous deck measured at the side amidships.

Moulded beam
This is the maximum beam, or breadth, of the ship measured inside the inner shell strakes of plating, and usually occurs amidships.
Moulded draught
This is the draught measured to any water-line, either forward or aft, using the moulded base line as a datum.
Extreme beam
This is the maximum breadth including all side plating, permanent fenders etc.
Extreme draught
This is obtained by adding to the draught moulded the distance between the moulded base line and a line touching the lowest point of the underside of the keel. This line is continued to the FP and AP, where it is used as the datum for the sets of draught marks.