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20. A bow thruster is a device used on large ships to aid
docking and exiting a dock without the
assistance of a tug boat. The most common style of bow
thrusteris is a propeller system that is
mounted in the lower area of the ship's bow. Directed from port
to starboard, or left to right, the
bow thruster is used to push the bow area of the ship away from
the dock when exiting port and
towards the dock when tying up the ship to the dock
2. !essel yaw curve described by the center of gravity of
the ship change the road, until the coming
of the new ship's path.
Ship Yaw phases are:
- The initial phase;
The initial phase of Ship Yaw initial commencing when the
steering angle
changes depending on the value of the new road; aboard ship
moves
laterally opposed placing the rudder, it lasted more than a few
tens of
seconds.
- Stage of evolution
Development phase starts from the point from which the ship is
turning
curve center of gravity of the vessel describe this curve which
has a
spiral!. "ongitudinal a#is of the vessel formed by the tangent
to the curve
bends yaw angle $ which increases with the yaw displacement
curve, up
to a ma#imum and then decreases to %ero, with the arrival of the
new road
- &hase of gyration.
&hase gyration, is uniform - called beginning at the end of
phase
evolution and tra'ectory moving ship and the appro#imate shape
of a
circle, the angle of derivation remains constant, the speed is
(ept
constant at amounting to )*.+* of the initial rate of yaw.
. wind waves or, more precisely, wind-generated
waves are surface waves that occur on the
freesurface of oceans, seas, lakes, rivers, and
canals or even on small puddles and ponds. They
usually
result from the wind blowing over a vast enough stretch of
fluid surface. "aves in the oceans can travel
thousands of miles before reaching land. "ind waves range in
si#e from small ripples to huge waves over
$% m high
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). signicant hight formula
/haracteristics period formula
24. &ix degrees of freedom
The motion of a ship at sea has the six degrees of
freedom of a rigid body, and is described as(2)
Translation:
. *oving up and down +heaving-
2. *oving left and right +swaying-
$. *oving forward and backward +surging-
Rotation
. Tilts forward and backward +pitching-
2. &wivels left and right +yawing-
$. ivots side to side +rolling.
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&hip movements on the wave. / 0eave
2 / &way
$ / &urge
1 / aw
3 / itch
4 / 5oll
0.
26.There are three special axes in any ship, called vertical,
lateral and longitudinal axes. The movements
around them are known as roll, pitch and yaw.
Roll
is the rotation of a vessel about its longitudinal
+side/to/side axis
Pitch
is the rotation of a vessel about its transverse +front6back
axis
Yaw
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is the rotation of a vessel about its vertical axis
1.
2 3ree surface tan(s
A single partially filled tank that extends across the
full breadth of the vessel. 7ts shape, si#e and
internal baffles allow the li8uid inside to slosh from
side to side in response to the roll motion of the ship.
The phasing of the roll moments acting on the ship and
the resultant li8uid motion will be such that it
reduces the roll motion. This type of tank was first
investigated by "illiam 9roude, but did not receive
much attention until the :3%s when it was revived and used in
many naval vessels. They have the added
advantage that it is possible to vary tank natural
fre8uency by changes in water level and thus
http://en.wikipedia.org/wiki/Baffle_(in_vessel)http://en.wikipedia.org/wiki/Baffle_(in_vessel)http://en.wikipedia.org/wiki/Phasinghttp://en.wikipedia.org/w/index.php?title=Roll_moments&action=edit&redlink=1http://en.wikipedia.org/wiki/William_Froudehttp://en.wikipedia.org/wiki/William_Froudehttp://en.wikipedia.org/wiki/William_Froudehttp://en.wikipedia.org/wiki/Natural_frequencyhttp://en.wikipedia.org/wiki/Natural_frequencyhttp://en.wikipedia.org/wiki/Baffle_(in_vessel)http://en.wikipedia.org/wiki/Phasinghttp://en.wikipedia.org/w/index.php?title=Roll_moments&action=edit&redlink=1http://en.wikipedia.org/wiki/William_Froudehttp://en.wikipedia.org/wiki/Natural_frequency
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accommodate changes in ships metacentric height. 9ree
&urface Tanks are commonly referred to as
;9lume; tanks.
2:. < = Tube Tanks
These partially filled tanks consists of two wing
tanks connected at the bottom by a substantial crossover
duct. The air column above the li8uid in the two tanks are also
connected by a duct. As in the 9ree
&urface Tanks as the ship begins to roll the fluid flows
from wing tank to wing tank causing a time varying
roll moment to the ship and with careful design this roll moment
is of correct phasing to reduce the roll
motion of the ship. They do not restrict fore and aft passage as
space above and below water crossover
duct is available for other purposes.
$%.
http://en.wikipedia.org/wiki/Metacentric_heighthttp://en.wikipedia.org/w/index.php?title=Wing_tanks&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Wing_tanks&action=edit&redlink=1http://en.wikipedia.org/wiki/Metacentric_heighthttp://en.wikipedia.org/w/index.php?title=Wing_tanks&action=edit&redlink=1
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)4 Slamming phenomenom
Slamming is the impact of the bottom structure of a ship
onto the sea surface. 7t is mainly observed while
sailing in waves, when the bow raises from the water and
subse8uently impacts on it. &lamming induces
extremely high loads to ship structures and is taken into
consideration when designing ships
"hipping response
Slamming induced whipping can significantly increase the
structural loading of ships. Although this is
well-known, the whipping contribution to the structural loading
is rarely taken into account when
computing the structural loading. An exception are the "dynamic
loading" factors found in
Classification Societies rules. Currently there are no
commercial tools available to compute the
seakeeping response including slamming induced whipping. his is
the main reason for not accounting
for the effects of whipping. !xtensive research has been done on
the subect of slamming impact and
whipping response but an integral and computationally efficient
method is not yet available for ship
structure designers.
#$.mooring sketch
A typical mooring scheme
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Number Name Purpose
>ow line revent backwards movement
2 9orward >reast line ?eep close to pier
$ After >ow &pring line revent from advancing
1 9orward @uarter &pring line revent from moving back
3 @uarter >reast line ?eep close to pier
4 &tern line revent forwards movement
The transport ships, bow anchor installation is made, usually of
two
anchor lines such mechanisms, while the stern anchor line has a
single
anchor.
33. A ships anchor is used to prevent the ship from
drifting from its location due to wind and
tidal currents, larger ships having two bow and one stern
anchor. There are numerous types of
ships anchors and the heavy ones are normally produced through
casting or drop-forged from
carbon steel.
This appendix discusses anchoring systems by type, performance,
holding capacity, and design, ascommonly used in salvage
operations. Ananchoring system consists of the anchor itself, the
mooring line that transmits forces from moored vessels
or pulling systems to the anchor, and
an attachment point or tensioning system on the moored vessel or
work platform. The anchor line
normally consists of chain, wire rope, or some
combination of the two, but may include fiber line or rigid
elements. The anchor provides the majority of
the resistance to motion, or holding
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capacity, but the contribution of portions of the anchor line
buried in or lying on the seafloor may be
significant, especially with chain. The
portion of anchoring system outboard of the attachment
point or tensioning system, including the anchor,
anchor line, and other ancillary devices,
is sometimes called the ground leg
•
)+. To provide a hydraulic system used for opening and
closing hatch cover, in
which a sequence valve having a large hysteresis is provided in
a hydraulic circuit
for opening and closing a folding hatch cover whose opening and
closing is
controlled by means of hydraulic cylinders, whereby it is
enabled to open and closethe hatch cover by a single changeover
valve and to prevent hunting of the
sequence valve. CO!T"T#T"O$ %ydraulic cylinders &, 4 used
for opening and
closing a folding hatch cover are operatively associated with a
sequence valve '(
having a large hysteresis and having therein a small)diametered
pilot chamber 20
and a large)diametered pilot chamber 2' and operation of these
cylinders &, 4 is
controlled by changeover valve '*. +hen the valve '* is
operated, cylinder & is
actuated at rst. +hen operation of cylinder & is nished,
pressure in conduit '- is
raised and sequence valve '( is switched, which in turn causes
actuation of cylinder
4. %ere, sequence valve '( is required to have a large
hysteresis so as to prevent
hunting of the same which is possibly caused after operation of
cylinder 4 is nished
)0. Operation of multifold crocodile hatch covers is eected
byhydrauliccylinders articulated between the dec/ and hinge arms on
theleadingcover panel of the rst pair. s this pair is opened to its
vertical,stowedposition the second 1trailing pair is drawn along
the longitudinalhatchcoaming to a position above a hinged crocodile
arm on each sideof it.
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hydraulic cylinder between the dec/ and the crocodile arm
isactuated,rotating the arm about its hinge, which lifts this
trailing pair ofcovers into
its stowed position.The operation is repeated for the third
trailingpair, if tted, for which additional crocodile arms are
provided. ll pairsaresecured in place on reaching their stowed
positions.!afe closing of the covers is ensured by a hydraulic
interloc/ingsystem inwhich the panels are moved sequentially, with
the outermosttrailing pairbeing operated rst.
3artial opening of the cover is easily achieved by
disconnectingthe hingebetween the leading and trailing pairs. "n
this way only theleading pair of panels is opened allowing
partial loadingunloading andbac/stowing of containers to be
carried out."n addition to their use for closing weatherdec/
hatches,multifoldcrocodile hatch covers may also be installed for
tweendec/
hatches as wellas for reefer vessels with small hatches.nother
ma5or benet ofthe systemis seen in tweendec/ installations where
the full height betweenthetweendec/ and weatherdec/ girders is used
for stowing thecovers in theiropen position.
System advantages:
5 up to three folding pairs per hatch cover stowage space
5 no ris( of hydraulic oil contamination of the cargo holds
5 easy on-dec( access to the operating system
5 facility for partial opening between folding pairs
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5 no re6uirement for a hydraulic wheel lifter
5 allows for bo# girder design of cover panels
36. Roll-on/roll-off (RORO or ro-ro
ships are vessels designed to carry wheeled cargo, such
asautomobiles, trucks, semi-trailer trucks, trailers, and railroad
cars, that are driven on and off the
ship on their own wheels. This is in contrast to
lift-on!lift-off ("#"# vessels, which use a crane
to load and unload cargo.
$#$# vessels have built-in ramps that allow the cargo to be
efficiently rolled on and off thevessel when in port. %hile smaller
ferries that operate across rivers and other short
distances
often have built-in ramps, the term $#$# is generally reserved
for larger oceangoing vessels.
The ramps and doors may be stern-only, or bow and
stern for &uick loading.
6oll)onroll)o ferries 16O6O are large, conventional
ferries named for the ease bywhich vehicles can board and
leave.
)1. Container ships are cargo ships that carry
all of their load in truck/si#eintermodal containers, in atechni8ue
called containeri#ation. They are a common means of commercial
intermodal freight
transport and now carry most seagoing non/bulk cargo.
$.
$:. pipelaying ship is a maritime vessel used in the
construction of subsea infrastructure. 't
serves to connect oil production platforms with refineries on
shore. To accomplish this goal a
typical pipelaying vessel carries a heavy lift crane, used
to install pumps and valves, and
e&uipment to lay pipe between subsea structures.
"ay methods consist of -lay and )-lay and can be reel-lay or
welded length by length.
*ipelaying ships make use of dynamic positioning systems or
anchor spreads to maintain thecorrect position and speed while
laying pipe.
$ecent advances have been made, with pipe being laid in water
depths of more than +,
metres.
http://en.wikipedia.org/wiki/Shiphttp://en.wikipedia.org/wiki/Cargohttp://en.wikipedia.org/wiki/Automobileshttp://en.wikipedia.org/wiki/Truckhttp://en.wikipedia.org/wiki/Semi-trailer_truckhttp://en.wikipedia.org/wiki/Trailer_(vehicle)http://en.wikipedia.org/wiki/Railroad_carhttp://en.wikipedia.org/wiki/Crane_(machine)http://en.wikipedia.org/wiki/Drawbridgehttp://en.wikipedia.org/wiki/Riverhttp://en.wikipedia.org/wiki/Sternhttp://en.wikipedia.org/wiki/Bow_(ship)http://en.wikipedia.org/wiki/Roll-on/roll-offhttp://en.wikipedia.org/wiki/Cargo_shiphttp://en.wikipedia.org/wiki/Intermodal_containerhttp://en.wikipedia.org/wiki/Containerizationhttp://en.wikipedia.org/wiki/Intermodal_freight_transporthttp://en.wikipedia.org/wiki/Intermodal_freight_transporthttp://en.wikipedia.org/wiki/Intermodal_freight_transporthttp://en.wikipedia.org/wiki/Subseahttp://en.wikipedia.org/wiki/Heavy_lifthttp://en.wikipedia.org/wiki/Dynamic_positioninghttp://en.wikipedia.org/wiki/Dynamic_positioninghttp://en.wikipedia.org/wiki/Shiphttp://en.wikipedia.org/wiki/Cargohttp://en.wikipedia.org/wiki/Automobileshttp://en.wikipedia.org/wiki/Truckhttp://en.wikipedia.org/wiki/Semi-trailer_truckhttp://en.wikipedia.org/wiki/Trailer_(vehicle)http://en.wikipedia.org/wiki/Railroad_carhttp://en.wikipedia.org/wiki/Crane_(machine)http://en.wikipedia.org/wiki/Drawbridgehttp://en.wikipedia.org/wiki/Riverhttp://en.wikipedia.org/wiki/Sternhttp://en.wikipedia.org/wiki/Bow_(ship)http://en.wikipedia.org/wiki/Roll-on/roll-offhttp://en.wikipedia.org/wiki/Cargo_shiphttp://en.wikipedia.org/wiki/Intermodal_containerhttp://en.wikipedia.org/wiki/Containerizationhttp://en.wikipedia.org/wiki/Intermodal_freight_transporthttp://en.wikipedia.org/wiki/Intermodal_freight_transporthttp://en.wikipedia.org/wiki/Subseahttp://en.wikipedia.org/wiki/Heavy_lifthttp://en.wikipedia.org/wiki/Dynamic_positioning
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The term pipelaying vessel or pipelayer refers to all vessels
capable of laying pipe on the
ocean floor. 't can also refer to dual activity ships. These
vessels are capable of laying pipe on
the ocean floor in addition to their primary job. /xamples of
dual activity pipelayers include barges, modified bulk
carriers, modified drillships semi-immersible laying vessels
among others.012
1%.A cable layer or cable ship is a deep-sea
vessel designed and used to lay underwater cables
for telecommunications, electric power transmission, or other
purposes. 3able ships are
distinguished by large cable sheaves012 for guiding cable
over bow or stern or both. 4ow sheaves,0+2
some very large, were characteristic of all cable ships.
5ewer ships are tending toward purestern layers with stern sheaves
only as seen in the photo of 3 Cable Innovator at the
*ort of
Astoria on this page. The names of cable ships are often
preceded by 3.. as in 3 Long Lines.062
The first transatlantic telegraph cable was laid by cable
layers from 17897. 't briefly enabled
telecommunication between /urope and 5orth America before misuse
resulted in failure of theline. 'n 17:: the Great
Eastern successfully laid two transatlantic cables, securing
future
communication between the continents.
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