Engine Room Construction Konstruksi Kamar Mesin

Fore End Structure

Jurusan Teknik Sistem PerkapalanFakultas Teknologi Kelautan ITS SurabayaME 091304Teknik Bangunan dan Konstruksi Kapal II1Stem2

On many conventional ships a stem bar, which is a solid round bar, is fitted.

Stem bar is fitted from the keel to the waterline region, and a radiused plate is fitted above the waterline to form the upper part of the stem.

This forms what is referred to as a soft nose stem, which in the event of a collision will buckle under load, keeping the impact damage to a minimum.

The solid round bar is welded inside the keel plate at its lower end, and inside the radiused stem plate at its upper end, the shell being welded each side.

2StemIt is necessary to support that part of the stem which is formed by radiused plates with breast hooks, i.e. horizontal plate webs, between the decks and below the lowest deck, in order to reduce the unsupported span of the stem.

Where the plate radius is large, further stiffening is provided by a vertical stiffener on the centre line.3

*Breast hook : Pelat segitiga mendatar di haluan kapal3Fore end structure4

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6StemOlder ships had solid bar stems which were riveted and of square section.

It could cause considerable damage on impact because of its rigidity.

Small ships such as tugs and trawlers may still have a solid stem bar extending to the top of the bow.

77StemSome existing large passenger ships may have steel castings or forgings forming the lower part of the stem.

A specially designed bow is required for ships assigned Ice Class and additional scantlings are required for the stems of ships assigned other ice classes.8

8Bulbous bowVessels operating at higher speeds, and those with high block coefficients, are often found to have a bulbous or protruding bow below the waterline.

From the construction point of view the bulbous bow does not present any great difficulty if this aspect has been considered when the bulb form is designed.

In general however a greater degree of plate curvature is involved, unless a rather convenient cylindrical form is adopted and fitted into the bow as a single unit.99Bulbous bowFloors are fitted at every frame space in the bulb, and a centre line wash bulkhead is introduced when the bulb is large.Transverses are fitted at about every fifth frame in long bulbs.Smaller bulbs have a centre line web but not a wash bulkhead.Shell plating covering the bulb has an increased thickness similar to that of a radiused plate stem below the waterline.10

10Chain lockerA chain locker is often arranged in the position forward of the collision bulkhead, below either the main deck or the second deck.

It can also be fitted in the forecastle or aft of the collision bulkhead in which case it must be watertight and have proper means of drainage.

Chain locker dimensions are determined in relation to the length and size of cable, the depth being such that the cable is easily stowed, and a direct lead at all times is provided to the mouth of the chain pipe.

Port and starboard cables are stowed separately in the locker.1111

Construction of chain lockerThe locker does not as a rule have the same breadth as the ship, but has conventionally stiffened forward and side bulkheads.

The stiffeners being conveniently arranged outside the locker if possible to prevent their being damaged.12*chain locker: bak/ceruk/gudang rantai12Hawse pipeTo provide an easy lead for the cable from the windlass to the anchors, the hawse pipes must be carefully fitted.

Tubular hawse pipes are generally fabricated. Castings are welded at the shell and deck to prevent chafing.

Additional stiffening in way of the hawse pipes is required at the side shell.1313

Hawse pipe14*Hawse pipe: tabung/pipa rantai jangkar1415

Bow thrusterWith the great increase in the size of the very large tankers, bulk carriers, containerships, passenger vessels, etc., directional control at low speed is of primary importance.

Bow thruster can help the maneuvering capability of ship at low speed especially when approaching the port for berthing.

The bow thruster unit may consist of:A shrouded propeller, where the shroud is movable and acts as a rudder.A transverse tunnel or duct through the ship near the bow in the narrow forward section. A reversible propeller is fitted on the center line of the tunnel to act as a pump discharging the water

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Fore end structure19

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21ReferencesShip Construction Sketches and NotesKemp and Young, Stanford Maritime London, 1984.

Ship Construction, Sixth Edition, D.J. Eyres, Butterworth-Heinemann, 2007

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