SHIP Fwd Arrangement

8/20/2019 SHIP Fwd Arrangement

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FORWARD ARRANGEMENT - STEM

• The stem is formed by a solid bar which runs from the

keel to the load waterline. In riveted ships this bar isrectangular , allowing the shell plating to beoverlapped and riveted by two rows of rivets. The shellplating is stopped about 10 mm from the fore edge ofthe bar in order to protect the plate edges. At the

bottom, the foremost keel plate is wrapped round thebar and, because of its shape, is known as a cofn plate. A similar form of construction is used at the top.

• In welded ships the bar is a solid round whichimproves the appearance considerably, particularly

where the keel and side plates overlap.• Above the stem bar the stem is formed by plating which

is strengthened by a welded stiener on the centre linethe plating being thicker than the normal shell platingnear the waterline but reduced in thickness towards the

top.



Strengthening of stem

• The plate stem is supported at intervals ofabout 1. m by hori!ontal plates known asbreast hooks, which e"tend from the frameto the ad#acent transverse frame. The breasthooks are welded to the stem plate and shellplating and are $anged on their free edge.

• %odern stems are raked at 1 degrees to &degrees to the vertical, with a large curve atthe bottom, running into the line of the keel.

• Above the waterline some stems curve forwardof the normal rake line to form a clipper bow.



FORWARD ARRANGEMENT



'anting Stringer





ARRANGEMENTS TO RESIST PANTING 1

• The side frames are spaced 310 mm apart and,being so well supported , are much smaller thanthe normal hold frames.

• The deck beams are supported by vertical anglepillar on alternate frames , which are connectedto panting beams and lapped n to the solid

$oors .• A partial wash 4 plate is tted to reduce the

movement of the water in the tank. -ntercostalsframes are tted for two or three frame spaces in

line with the centre girder . The lower part of thepeak is usually lled with cement to ensuree5cient drainage of space .

• 6etween the collision bulkhead and 1 length

from forward the main frames, together with theirattachment to the margin and are increased in



A((A)*+%+)TS T (+S-ST

'A)T-)* &• 8ight side stringers are tted in the in line with those in the peak.

These stringers consist of intercostals plates connected to theshell and to a continuous face angle running along the toes of theframes. These stringers may be dispensed with if the shell platingis increased in thickness by 1. This proves uneconomical whenconsidering the weight but reduces the obstructions to cargo in

the hold . The peak is usually used as a tank and therefore suchobstructions are of no importance.

• The collision bulkhead is stiened by vertical bulb plates spacedabout 300 mm apart inside the peak. -t is usual to t hori!ontalplating because of the e"cessive taper on the plates , whichwould occur with vertical plating. 9ig. construction of a collision

bulkhead.• The structure in the after peak is similar in principle to that the

fore peak, although the stringers and beams may be tted &. mapart. The $oors should e"tend above the stern tube or the.frames above the tube must be stiened by $anged tie plates toreduce the possibility of vibration. The latter arrangement is in 9ig



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Arrangement to reducepounding

• The structure is strengthened to resist the

eects of pounding. The collision bulkhead is& of the ship/s length from the forward .

• The $at bottom shell plating ad#acent to thekeel on each side of the ship is increased inthickness by between 1 and >0depending upon the length of the ship. largership have smaller increases

•

-n addition to increasing the plating, theunsupported panels of plating are reduced insi!e . -n transversely framed ships the framespacing in this region is 700 mm compared

with 70 mm to ?00 mm amidships .



Arrangement to reducepounding &

• longitudinal girders are tted &.& m apart , e"tendingvertically form shell to the tank , while intermediatehalf@height girders are tted to the shell. reducing theunsupported width to 1.1 %.

• Solid $oors are tted at every frame space and areattached -f the bottom shell of a ship is longitudinallyframed, the spacing of the longitudinal is reduced to700 mm and they are continued as far forward aspracticable to the collision bulkhead.

• The transverse $oors may be tted at frames with thisarrangement and the full@height side girders may betted &.1 m apart. <alf@height girders are not reuired



'rinciple of 6ulbous bow• -f a sphere is immersed #ust below the surface and pulled though

the water, a wave is created #ust behind the sphere. -f such asphere is superimposed on the stem of a ship, the wave from thesphere interferes with the normal bow wave and results in asmaller bow wave, Thus the force reuired to produce the bowwave is reduced . At the same time, however, the wettedsurface area of the ship is increased, causing a slight increase

in the rictional resistance.

• In slow ships the eect of the bulbous bow could increasethe total resistance

• In ast ships, where the wave making resistance orms, alarge proportion o the total resistance, the latter is reducedby tting a bulbous bow.

• A bulbous bow , also increases the bouncy orward and

hence reduces the pitching of the ship to some small degree.



BULBOUS BOW





ANCHOR AND CABLE ARRANGEMENTS

• A typical arrangement for raising ,lowering and stowing the anchor of a shipshown in the gure . The anchor isattached to :

• aB heavy chain cable which is led to

• bB the hawse pipe over

•

cB the windlass and down through a• (d)chain pipe or spurring pipe into

the

• (e) chain locker.



The hawse pipes

•

The hawse pipes may be constructed of mild steeltubes with castings at the deck and shells or castin one complete unit or each side o the ship .

• There must be ample clearance for the anchorstock to prevent #amming and they must be strongenough to withstand the hammering which theyreceive from the cable and the anchor.

• The shell plating is increased in thickness in way of

each hawse pipe and ad#acent plate edges are ttedwith moldings to prevent damage. A chang pieceis tted to the top o each hawse pipe, while asliding cover is arranged to guard the opening



An!o" !#$n #n%

w$n%l#ss• T!& cable stopper is a casting with a hinged lever ,

• which may be used to lock the cable in any desired position andthus relieve the load from the windlass either when the anchor isout or when it is stowed.

• The drums o the windlass are shaped to suit the cable and areknown as cable lifters . The cable lifters are arranged over the

spurring pipes to ensure direct lead of the cable into the lockers .• The windlass may be either steam or electric drive.

• !arping ends are tted to assist in handling the mooring ropes.

• The windlass must rest on solid support with pillars andrunners in way of the holding down bolts, a 7mm teak bed being

tted directly beneath the windlass.• The chain pipes are o mild steel , bell mouthed at the bottom.

• The bells may be o cast iron, well rounded to avoid chang. The pipe are tted as near as possible to the centre of the chainlocker for ease of stowage .



2<A-) 82;+( @1

• The chain locker may be tted between the upper and

second decks, below the second deck or in the forecastle. -tmust be of su5cient volume to allow adeuate headroomwhen the anchors are in the stowed position. The locker isusually situated forward of the collision bulkhead, usingthis bulkhead as the after locker bulkhead.

• The locker is not normally carried out to the ship side. Thestieners are preferably tted outside the locker to preventdamage from the chains. -f the locker is tted in theforecastle, the bulkhead may be used to support thewindlass.

• " centerline division is tted to separate the twochains and is carried above the stowed level of the chainbut is not taken up to the deck.

• -t is sti#ened by means of solid hal round bars whilethe top edge is protected by a split pipe.



C!#$n lo'&" -2

• $oot holds are cut in to allow access from oneside to the other. A hinged door is tted in theforward bulkhead, giving access to the lockerfrom the store space.

• %any lockers are tted with alse &oors toallow drainage of water and mud, which iscleared by a drain plug in the forward bulkhead,leading into a drain hat from where it is discharged

by means of a hand pump.• The end of the cable must be commented to the

deck or bulkhead in the chain locker . A typicalarrangement is shown in 9ig.



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SHIP Fwd Arrangement

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