Marine scientia

Magnetic compass

2021-03-04T08:49:00.001+05:30

The magnetic compass is fitted on the upper bridge exactly center line of the ship
It is referred to as standard compass

1.Dry Card

2.Wet Card

A compass point north because all magnets have two poles north pole, south pole.
The north pole of the one magnet attracted towards the south pole of another magnet

DRY CARD COMPASS

A light aluminum ring about 254mm in diameter is attached to a brass hub by silk cord which is threaded in and out through holes in the ring.
This tight silk cord is act like bicycle wheels.
There is no other connection or support between the ring and the hub.
Silk cord is used because it doesn’t shrink or stretch due to moisture or change in atmospheric temperature.

Card support: -

The bottom of the hub has small cap fitted with a sapphire bearing surface.
This rests on a pivot tipped with iridium which is hard nonmagnetic metal.
This arrangement provides practically friction-less support, for the compass card and requires no lubrication.

The sapphire cap has a polishing effect on the iridium. the smoothness of rotation of the compass card thus improves over the years.
The compass card is made of rice paper because it is very light and unaffected by changes in temperature.
The rice paper is divided into several segments and each is stuck to aluminum ring and to the silk cord using light waterproof adhesive.
The reason for the division of cards into segments is that if a drop of water was to fall at any part of the compass card only that segments gets distorted.

Directive element: -

This consists of 3,4 or 5pairs of needle magnets suspended, parallel to each other, a few centimeters below the compass card
Symmetrically Arranged on either side of card

The ends of magnets have holes on them, silk cord pass through these and through holes in the bottom of the aluminum ring to support the magnets below the compass card
By this method, center of gravity of the entire compass card, inclusive of magnets is below the tip of the pivot.
This ensures that the card is not only north seeking but also remains horizontal even when the pivot tilts out of vertical during rolling or pitching.

The compass bowl :-

The compass card is enclosed in a cylindrical brass bowl having a transparent glass top and a frosted glass bottom
The glass top is retained in position by a brass ‘verge ring’ which is secured to the bowl by equidistant,brass screw along the circumference
The rubber washer between verge ring and the top glass ensures water tightness
The top of the verge ring is grooved to accommodate the azimuth mirror
The vertical distance between the top of the hub of the card and the top glass is such that even if the bowl is inverted the card wouldn’t completely disengage from the pivot so that when the bowl is returned to upright,the card would again rest properly on the pivot as before.

The lubber line:-

On the forward,inside part of the bowl, there is small projection with a line marked on it.
This line is called the lubber line
This represents the direction of the ship’s head.

The compass is fixed on the center line of the with lubber line aligned toward forward.

Suspension bowl:-

On the outside of the compass bowl ,there are two athwart ship projections called gimbals,at the same level as the compass card.

The gimbals are triangular in cross-section,apex downward.
These gimbals rest on V shaped depression in a horizontal ring called the gimbal ring which encircles the compass bowl.
The gimbal ring itself pivoted at its forward and after sides.if the ships rolls or pitches the bowl would remain horizontal because its COG is well below the gimbals.

The binnacle:-

The binnacle is a cylindrical container made of teak wood and brass.
Non magnetic materials are used in its construction.
If the screws are of brass and the nails,copper.the compass bowl is slung inside the top portion of the binnacle.
The middle portion is accessible by a door and contains an electric bulb.

Corrector magnets:-

In the centre of the lower half of the binnacle,there are a number of horizontal holes,the fore , aft and athwartships,for hard iron or permenent corrector magnets which are meant to offset undesirable disturbing,magnetic effects caused by the ship s steel hull.
These holes are accessible by means of door in the binnacle. The number of the corrector magnets and their distances from the compass card,are decided by a qualified compass adjuster during compass adjustments of ships.
The lower two third of the binnalce has a vertical brass tube at the center in which slides a bucket. This bucket has some magnets in it called heeling error magnets.
This bucket is held in position by a brass chain.
The number and the location of each magnet in this bucket and the distance of the bucket from the comass card must not be altered except during compass adjustment by a qualified compass adjuster.the door giving acccess to the corrector magnets should always remain locked and opened only during compass adjustment

Quadrantal correctors :-

These are two soft iron spheres which are fitted in brackets one on either side of the binnacle.the brackets are sloted so that the distance between the spheres can be altered as desired during the compass adjusment

Flinders bar:-

This is soft iron correctors inserted in 60cm long brass case ,fitted vertically on the forward or on the aft part of the binnalce.if the ship has more superstructure abaft the compass,the flinders bar is fitted on the forward part of the binnacle and vice versa

The helmet

The top of he binnacle is provided with a large brass helmet.this protects the comapss bowl from direct sunlight ,rain ,spray,dew etc. during non use.

Care and maintenance :-

The doors giving access to the corrector magnets should always be kept locked and the key is safe in custody.
The wooden parts of the binnalce should be varnished,not painted as paint may cause doors to jam.
The soft iron spheres (quadrantal correctors )and their brackets should be painted to prevent rust.
The brass part of the binnacle should be polsihed regualarly
The binnalce light should be switched off during day time
All machinery materials such as ariels,stays,elctrical machinery and wires should be kept well away from the compass .
Prevent salt and dust particle settling on the azimuth mirror and the comapass bowl.
Prevent spray and precipitation from falling on the azimuth mirror and the comapss bowl.
Protect the azimuth mirror and the comapss card from the direct sunlight

Long Range Identification and Tracking ( LRIT )

2021-03-02T21:34:00.001+05:30

LRIT is a reporting system which is developed to enhance the safety and security of ships and also assist in search and rescue operation.

LRIT allows member state to receive position reports from vessels operating in proximity to states coastline. As it works on satellite communication , worldwide communication is possible. It has no fixed channels.

The LRIT information is not available to ships nearby. The information are available only to coastal states, flag state, search and rescue centers upon a request through a system of regional, national and International LRIT data exchange center.

credits: IMO

Details transmitted are:

ships identity
ships location
date and time of transmission

LRIT system consists of:

communication service provider
application service provider
LRIT data centre
Information transmitting equipment
LRIT distribution plan

LRIT is an independent system and is not interfered with AIS.

Information can be received by:

Flag state
Port
Coastal state
Search and rescue centre

DAMAGE STABILITY

2020-11-03T21:42:00.004+05:30

Archimedes Principle:-

When a body floats freely in the water the mass of the body is equal to the mass of the water that the body presses away at the corresponding draught.

Change in draught

When a ship has one or more damage compartments the draught will increase to compensate the loss of buoyancy from the damaged compartments. A new equilibrium of the floating position occurs.

Heeling angle

If the damage is unsymmetrical around the center line, the ship will heel.

Change of trim

If the damaged compartments are in the fore ship or in the aft ship, a significant trim will develop.

Change in stability parameters

The sea “feels” the hull of the damaged ship as if the damaged compartment were non existent

Centre of gravity and Centre of buoyancy

The stability parameter of the ship is affected by the damage .the underwater hull is completely different and thereby the stability parameter .if the cargo and the fluids in tanks still is onboard the ship after the damage ,G will remain on its original location. B will change position so that B and G lie on the vertical line.

Metacentric radius BM

The metacenter, M, will change location since the shape of the underwater hull has changed. The metacentric height ,GM, will often decrease ,but can in fact sometimes increase ,depending on the width of the damage. The location of M depends on the displacement of the ship and the moment of inertia of the water plane area around the longitudinal axis through the cof by the formula

BM=moment of inertia of the water plane area /volume of the displacement.

If the damaged compartment extends above waterline, they will cut a hole in the water plane and reduce the moment of inertia.

Damage extending above original waterline

Since the displacement is constant the distance BM will be reduced .B will rise a little due to increased draught, but not so much as decrease of BM .This means that G will be closer to M after the damage and the ship will have a smaller GM.

DAMAGE NOT REACHING THE ORIGINAL WATERLINE

If the damage only affects, for example, double bottom the w/p area will be almost unaffected. A little increase of draught gives larger w/p area and a slightly increased moment of inertia.

This means that the distance BM will increase and the increased draught will push B upwards consequently GM will increase.

DAMAGE STABILITY CALCULATION

This can be done by two methods

1. Added weight method

2. Loss of buoyancy method

And thereby we can understand the GZ affected by damage.

LOSS OF BOUYANCY

In the loss of buoyancy method, which can be regarded as the true method, the ship will have a new under water hull form and a new equilibrium is calculated based on this.

Procedure:-

1. Calculate the volume of the flooded seawater, i.e., the loss of buoyancy, by multiplying the displacement to the original waterline of the damaged compartment with the volume permeability of the compartment.

2. Calculate the change in draught and the new location of longitudinal Centre of floatation, TCF for the remaining water plane area, when damaged compartments are taken away.

3. Calculate moment s of inertia for the remaining water plane area based on the new Centre of floatation, both transverse and longitudinal. Thereafter calculate the new BM.

4. Calculate the new location of B above the keel.

5. Calculate the new GM.

6. Calculate the heeling angle and trim.

Correction of GZ curve: - True GZ for the actual damage can be calculated only if the cross curves ,KN values ,are calculated for the damaged hull.

The loss of buoyancy method is not recommended when doing damage stability calculation manually. The method is more suitable for programming on computer calculations.

2. ADDED WEIGHT METHOD

For manual calculation, this method is more easier.it is similar to an ordinary load calculation where the flooded seawater is added weight. Based on this new stability parameter found out from hydrostatic tables and cross curves for the ship.

PROCEDURE:-

1. Estimate the mass of the flooded seawater and use this as an added weight.

2. The new draught and displacement for the ship is calculated based on this added weight

3. Estimate the location of cog of the flooded sw and calculate the effect on the cog of the ship.

4. Calculate the new gm for the new draught and location of G.

5. Calculate the free surface effect; since the added weight is liquid, the reduce in GM is found by the formula

GGv= (I/ ) + (Ay²/ )

I= moment of inertia of the water plane area

= volume of the displacement

A=AREA OF THE FREES URFACE

Y = the distance between the Centre line of the ship and the area Centre of the free surface.

6. Calculate the new trim and list.

7.correction of GZ curve

Recovery of Person from Water

2020-10-31T16:10:00.000+05:30

Learning Objectives:

factors to be taken into account when recovering persons from water
risk assessments to be done
use of rescue craft, merits, demerits and other options
recovery plan
first aid after recovery from cold water

Factors for consideration:

manoeuvrability of ship:

For a large ship it is very difficult to come alongside a small target like survival craft or a person in the water. The other danger is that of running over and / or crushing the target.

Manoeuvring your own ship at slow speed judging its movement and that of survival craft/ person in water is a skill. Appropriate training shall be encouraged by operators and owners of all ships.

freeboard of the ship:

Small crafts are vulnerable if they are in close proximity with the ship as there is a danger of crushing or other damages. Also people awaiting recovery may not have experience of such operations.

Survivors need to be lifted considerable distances to get into the ship. Climbing a pilot ladder is impossible for a person who is not fit.

For vessels with high freeboard it may be difficult to see the target , hence there is great danger of running over the target. Thus additional lookouts with direct communications to the Bridge must be posted.

Risk assessment:

Recovery operations should be conducted at a position clear of the ship's propellers and usually within the ships parallel mid-body section. All areas need to be risk assessed for the conditions at the time of rescue. Some of them are:

Ship specific characteristics such as manoeuvrability, access points etc. The risk assessment must be done in accordance with company's SMS.
The equipment's that shall be used
weather conditions
will it cause any risk to stability of ship
can means of recover be safely rigged
points of entry

Equipment:

Even if some purpose built recovery equipment's are there, it may not be enough in certain circumstances.

It is always better to lift a person as the person may not be fit to climb a ladder.

Lower ends must be 2m below the water line to help people in water get on them. Safety lines should be rigged alongside with rescue strops and someone must be posted to lookout the operations.

Horizontal recovery:

When lifting the people, if possible, it must be done in a horizontal or near-horizontal position. This minimizes the risk of shock induced by sudden transfer from the water and from hypothermia.

Lifeboats and life-rafts may also be used to transfer people from survival crafts and lifted to embarkation deck.

If winch-fitted helicopters are on scene, it may be used. Transferring people from helicopters has special requirements which is described in IAMSAR manual

Good seamanship:

Approach with the significant element ( wind,sea or swell) on weather bow and the target on your lee bow.

As you approach, turn away from the weather and stop to create the lee, with recovery target on lee side.

It will be very difficult to spot the target from the Bridge, thus sufficient lookouts with communication arrangements with the Bridge must be posted.

Advantages and Disadvantages of using lifeboats/rescue boats:

- easier for people to get in due to low freeboard
- easy to manoeuvere . Thus approaching the target is easier
- can be used to lift causalities back on to the ship

Disadvantages:

only limited number of people can be brought at a time
it is only safe to launch lifeboats in good to moderate sea and weather conditions

The people in charge of such operations must be familiar with guidance given in IMO circular MSC 1182, guide to recovery techniques.

Recovery Plan

The conditions at recovery scene cannot be predicted, but a recovery plan must be drawn up based on different scenarios like weather conditions, number of survivors, equipment's to be used etc.

Thus in an emergency situation most of what has to be done is already known by the crew. Every rescue is unique and good consideration of risks have to be applied to the situation that presents itself.

Drills should be conducted on board to ensure that crew are familiar with plans,procedures and equipment's for recovery of persons from water. The ships Master should ensure that there are enough drills and instructions to make sure that all crew know their duties during the recovery of persons.

First aid after recovery from cold water

Always obtain medical advice as soon as possible.

IAMSAR

2020-10-30T12:36:00.002+05:30

IAMSAR (INTERNATIONAL AERONAUTICAL AND MARITIME SEARCH AND RESCUE MANUAL. )

The primary purpose of the 3 volumes of IAMSAR is to assist states in meeting their own search and rescue and the obligation they accepted under the convention on INTERNATIONAL CIVIL AVIATION, THE INTERNATIONAL CONVENTION ON MARITIME RESCUE AND SOLAS CONVENTION.
These volumes provide guide lines for common aviation and maritime approach to organizing and providing SAR service states are encouraged to develop and improve their SAR services co- operate with neighbor states and to consider their SAR services to be part of a global system.
VOLUME 1:- The organization and management volume discusses the global SAR system concept, establish and improvement national and regional SAR systems and cooperation with neighboring states to provide effective and economical SAR.
VOLUME 2:- the mission coordination volume assists personnel who plan and coordinate search operation and exercises.
VOLUME 3:- The mobile facilities volume is intended to be carried aboard rescue unit, aircrafts and vessels to help with performance of a search, rescue or on scene coordinator function and with aspects of SAR that pertain to their own emergencies.
IAMSAR Volume 3. This manual should be carried aboard rescue unit

The volume is published jointly done by the

1. International maritime organization

2. International civil aviation organization

DESIGNATION OF AN ON SCENE COORDINATOR.

When two or more SAR facilities conduct operation together, the SMC should designate an OSC.
If this is not possible, the facilities involved should by mutual agreement designate an OSC.
This should be done as early as practicable and preferably before arrival into the search area.
Until the OSC has been designated, the first facility arriving at SAR scene should assume his duties of OSC.
When deciding how much responsibility to delegate to the OSC the SMC normally consider the communications and personnel capabilities of the facilities involved.

DUTIES OF ON SCENE COORDINATOR

Coordinator operation of all search and rescue facilities on scene.
Receives the search action plan or rescue plan from all SMC or if no search and rescue plan is otherwise available then the search and rescue plan.
Modify the search action or rescue action plan as the situation on scene dictates keeping the SMC advised.
Coordinate on scene communications.
Ensure SAR operations are conducted safely, paying particular attention to maintaining safe separation among all facilities both surface and air.
Make periodic situation reports to the SMC , the situation report should include ABOUT BUT NOT limited to

1. Weather and sea condition.

2. The result of search to date.

3. Any action taken.

4. Any future plans or recommendation.

Maintain a detailed record of the operation including

1. On scene arrival and departure times of SAR facilities other vessels and aircrafts engaged in the operation.

2. Areas searched

3. Track spacing used

4. Sightings and leads reported

5. Action taken

6. Result obtained.

Advice the SMC to release facilities no longer required.
Report the number and names of survivors to the SMC
Provide the SMC with the names and designations of facilities with survivors on board.
Report which survivors re in each facility.
Request additional SMC assistance when necessary (medical evacuation of seriously injure survivors)
OSC should ensure that reliable communication are maintained on scene

DUTIES OF THE SAR MISSION COORDNIATOR(SMC)

Each SAR operation is carried out under the guidance of an SMC. This function exist only fo the duration of a specific SAR incident performed by the RCC chief or designee.
The SMC should be well trained in all SAR process or plans.
Gather information about distress situations.
Develop an accurate and workable SAR action plans.
Dispatch and coordinate resources to carry SAR missions.
Obtain evaluate all data on the emergency.
Ascertain type of emergency
Remain informed of prevailing conditions.
If necessary, ascertain movements and location of vessel and alert shipping in likely search areas for rescue, lookout and radio watch.
Plot search areas to decide on methods or facilities to be used.
Develop search action plan and rescue action plan as apt
Arrange briefing and modify search action plan if necessary make arrangement for accommodation of SAR personnel.
Arrange for delivery of supplies to sustain survivors.
Maintain in chronological order up to date record.
Issue progress reports
Recommend to RCC chief abandoning or suspending the search.\
Release the SAR facilities when assistance is no longer required
Notify accident investigation authorities
Notify state of registry of aircraft and prepare a final report.

PRECAUTIONS WHEN USING HEAVY GEARS.

2020-09-12T16:18:00.003+05:30

The term "gear" refers to those equipment's which are used to load/unload cargo or to carry out any deck operations. one must be very careful when using heavy gears and all sort of precautions must be taken.

workers need to be careful about what they are doing ,and they must always be aware of other workers around them. Particularly co-workers using forklifts and other forms of material handling equipment.
Be on the lookout for these dock hazards.

1.slipping and tripping on wet ,oily ,or broken floor surfaces .

2.falling on dock edges.

3.injuries from falls and unsecured dock plates.

4.illness or unconsciousness from inhaling CO from trucks.

5.Back injuries.

keep the floor clean,dry and in good condition.
cleanup properly and dispose of the trash.
clean up any spills immediately.
Take precaution to prevent accidents while lifting.
walk,don't run ,on loading decks.
wear sturdy shoes with non-skid soles that support both the foot and ankle.
work safely with trucks and trailers.
Load and upload correctly to prevent injuries.
use forklifts ,dollies and other aids to get help rather than lifting by yourself whenever possible.
keep tight the load towards your belly and lock it up
wear PPE (personal protective equipment) always.
Never stand on hatch covers
never look into unguarded holds.
be aware of safe working loads.

FIREFIGHTING PROCEDURES IN DRYDOCK.

2020-09-12T13:02:00.005+05:30

The possibility of fire aboard the ship or elsewhere within the dockyard complex is always unwelcome. As with any other fire incident the alarm should be raised as soon as possible after the discovery of the fire and the following procedures are suggested. Assuming that the crew have remained onboard and the fire is onboard the vessel , after the alarm has been raised..

Muster an emergency fire party and attempt to contain and extinguish the fire immediately following its discovery.
if alarm is not working / given for maintenance,the fire witness should shoutouts the nature and location of fire.
Non essential personnel should be evacuated to the store and the fire brigade should be contacted.
A gangway watch should be set out to ensure that the access to the vessel is not blocked which would deny accessibility to firefighters.
fire lines should be kept charged via shore through ISSC
Emergency teams to fight the fire and evacuate casualties.
technical team cut necessary electrical supply etc.
The minimum water volume should be used when tracking fires in drydock because of stability dangers,while on the blocks.the possibility of shoring is directly affected by heat or flame which,combined with excessive water volume ,could cause the vessel to move from the block.
the ship's sides should be cooled, especially in the way of the shores.These must not be allowed to become dislodged by the effects of fire and the heat effects on steel hulls.
any gas bottles are extremely hazardous and susceptible to explosion when in contact with excessive heat.
The affected space is not open and exposed for repairs.The use of CO2 is preferable to water as a fire fighting option.The admission of water into the docked vessel is highly undesirable and its use if possible should be restricted to boundary cooling of decks and the shell sides.

Basic CARGO WORK definitions

2020-09-10T22:17:00.004+05:30

STOWAGE FACTOR : it shows the space occupied by a tonne of cargo.

It is the volume occupied by a unit weight of cargo. Generally it is expressed in:

cubic meters/ tonne ( metric)

( 1 metric tonne=1000kg)

cubic feet/ long ton

( 1 long ton=1016 kg)

for eg: stowage factor of iron ore=0.40 cubic m / metric tonne

this means that for storing one tonne of iron ore 0.40 cubic m is required.

stowage factor= volume/ mass

( density = mass/volume)

thus stowage factor is the reciprocal of density. Cargoes with high density have low stowage factor and vice-versa

BROKEN STOWAGE : It is the space between packages which remains unfilled.

This factor varies according to type of cargo and shape of hold.

Broken stowage will be higher for packages with large size and irregular shape.

This factor is always expressed as percentage of the volume of cargo.

broken stowage=(gross volume - net volume * 100)/ net volume

NOTE:

to obtain correct volume of cargo, broken stowage must always be added to stowage factor.

TOTAL VOLUME = STOWAGE FACTOR+BROKEN STOWAGE

LOAD DENSITY : It is the maximum weight that can be safely loaded on a unit area. It is expressed in tonnes/ sq.m.

The height to which cargo can be stowed on a deck will depend on load density of that deck and stowage factor of the cargo.

DEADWEIGHT CARGO: It is the cargo on which freight is charged on its weight.

MEASUREMENT CARGO: It is the cargo in which freight is charged on the volume occupied by the cargo.

OPTIONAL CARGO: It is the cargo which is to be discharged at one port or another as decided by the shipper before the ship reaches the discharge ports. such cargo must be stowed as to be available at either of the optional ports.

BALE CAPACITY:

It is the cubic capacity of a space when:

breadth is taken from inside of cargo battens

depth from tank top to underside of deck beams

length from inside of bulkhead stiffeners or spar ceiling where fitted

GRAIN CAPACITY:

It is the cubic capacity of a space when length,breadth and depth are taken right to the plating. Allowance is made for volume occupied by frames, beams and stiffeners.

Obviously the bale capacity will be less than grain capacity. Inmost cases sometimes they can be equal in certain bulk carriers, ro-ro ships etc.

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ADMIRALTY TIDAL PUBLICATION

2020-09-07T13:57:00.003+05:30

1.GENERAL ARRANGEMENT:-

PART 1:-Part 1 is that these tables give daily predictions of the times and heights of high and low waters at a selected number of standard ports.

This list of standard ports is given inside the front cover included with each set of prediction for standard ports (with exception of venezia) is a diagram to facilitate the calculation of heights at times other than high and low water .

An explanation of the use of the diagram is given in the instruction for the use of tables(page xii).
The introduction of part 1 deals with a number of subjects of general interest, particularly the effect of meteorological condition on tidal heights.
PART 2:-It gives data for prediction at a large number of secondary ports ,this is in the form of time and height differences referred to one of the standard ports of part 1.
PART 3:-it gives data of the harmonic constant for use with the simplified harmonic method of tidal prediction NP.159.
In those cases where harmonic constants are given, two alternative methods of predictions are available.

2.SOURCE OF TIDAL PREDICTIONS:-

Predictions for some standard ports in the British isles and elsewhere are computed on behalf of the harbour authorities by the oceanographic laboratory ,bidston,others are prepared by the hydrographers of the navy.
predictions for the remaining standard ports are received from the appropriate authorities in Denmark , France ,Germany ,Netherlands,and Norway.
Data in part2 for places outside the British isles are ,in general, extracted from the tide tables published by the appropriate national authority.
A list of authorities responsible for the observations , analyses and predictions at standard ports is given in table v (page xxxvii).

3.SPECIAL PREDICTIONS FOR SECONDARY PORTS.

The hydrographic office can supply daily predictions for secondary ports,either as times and heights of high and low waters or S hourly heights, upon request.

4.TIMES USED FOR PREDICTIONS IN VOL1.

All the times of predictions in part 1 are given in the standard time kept at the place. In the British isles the time used is universal time (GMT).

5.HEIGHTS OF PREDICTIONS.

All predicted heights in part 1 are given in meters above chart datum.The height difference in part3 are also given in meters

SOLAS REQUIREMENTS::LIFEBUOY

2020-09-04T14:53:00.002+05:30

A lifebuoy is a ring shaped floating life preserver. All ships must carry adequate number of lifebuoys as per SOLAS regulation. Lifebuoys provide an additional flotation to crew/passengers until they are rescued.

lifebuoy specifications:

Have an outer diameter of not more than 800 mm and an inner diameter of not less than 400 mm.
Be constructed of inherently buoyant material.
Be capable of supporting not less than 14.5 kg of iron in fresh water for a period of 24 hours.
Have a mass of not less than 2.5 kg and more than 6kg.
Not sustain burning or continue melting after being totally enveloped in a fire for a period of 2 seconds.
Be constructed to withstand a drop into the water from the height at which it is stowed above the waterline in the lightest seagoing condition or 30 m, whichever is the greater, without impairing either its operating capability or that of its attached components.
If it is intended to operate the quick release arrangement provided for the self-activated smoke signals and self-igniting lights, have a mass of not less than 4kg.

Be fitted with a grab line not less than 9.5 mm in diameter and not less than four times the outside diameter of the body of the buoy in length. The grabline shall be secured at four equidistant points around the circumference of the buoy to form four equal loops.

NUTSHELL:

SIZE	Inner diameter : 400mm outer diameter : 800mm
MATERIAL/ CONSTRUCTION	Inherent buoyant material must not get damaged when dropped from 30m in lightest sea going condition or from the place where it is stowed.
MASS	> 2.5 kg and < 6 kg must support 14.5 kg of iron in fresh water for not less than 24 hours. If smoke/light signal equipped buoys, mass not less than 4 kg.
GRABLINE	Diameter : not less than 9.5mm must be secured at 4 equidistant point around the circumference of the buoy
WHEN TOTALLY ENVELOPED IN FIRE	Not sustain burning/ melt continuously for a period of 2 seconds

Required number of lifebuoys

Length of vessel (m)	Lifebuoys required
Up to 100m	8
100-150 m	10
150-200 m	12
200 m and more	14

lifebuoys self-igniting

As the name suggests lifebuoys which have special arrangements on them so that at night time the light ignites indicating hazard.

At least one half of the total number of lifebuoys must be provided with self igniting lights.

SOLAS requirements are as follows:

lights should not be extinguished by water
must be white in colour.
luminous intensity of not less than 2 cd

must spread light in all directions of upper hemisphere or flash at a rate greater than 50 but less than 70 ( >50 flashes but < 70 flashes) per minute for a period of 2 hour.

lifebuoys self-activating smoke signals

Requirements are as follows:

emit smoke at a uniform rate for a period of at least 15 minutes when floating in calm water.
not emit any flames or ignite explosives during the entire time of emission of smoke
not be swamped in a seaway
must emit smoke for at least 10 seconds if submerged in water
must be provided with quick release arrangement

Buoyant lifelines

A buoyant lifeline includes a lifebuoy rings and a safety hook. It is thrown to drowning personal.The drowning man sets the ring on his arm and then bend his arm, thus will save him from drowning.

Requirements:

At least one lifebuoy on each side of ship is fitted with a buoyant lifeline.
it must be non-kinking
diameter not less than 8mm
breaking strength not less than 5kN.

DIFFERENT TYPES OF VENTILATION.

2020-09-04T10:47:00.001+05:30

1.THROUGH VENTILATION.

This is done by trimming the leeward ventilator into the wind and windward ventilator away from wind. The direction used here is apparent wind direction.

2.SURFACE VENTILATION.

This is done by the ventilator turned into the wind and the leeward turned away from the wind . This is necessary for certain cargoes where only the surface cargo is to be ventilated.

eg:- coal…

3.FORCED VENTILATION.

It is achieved by using mechanical fans and there by the air in the hold is dried and recirculated.

types of segregation as per imdg code

2020-09-04T09:54:00.001+05:30

Dangerous goods belonging to different classes cannot be stored together.they have to be segregated from one another and the segregation depends on the properties of substances in each class and the way they react with substances of another class. List of segregation as per IMDG CODE

TYPES OF SEGREGATION.

1.AWAY FROM :-May be carried in the same compartment or on deck provided a minimum horizontal separation of 3m projected vertically is maintained.

2.SEPERATED FROM :- Can be carried in the same compartment if the intervening deck is resistant to fire and liquids, otherwise separate holds.On deck, horizontal separation of at least 6m.

3.SEPERATED BY A COMPLETE COMPARTMENT OR HOLD FROM:- These must be either a vertical or longitudinal separation by a complete compartment or hold and two bulkheads or deck resistant to fire and liquids.

4.SEPERATED LONGITUDINALLY BY AN INTERVENING COMPLETE COMPARTMENT OR HOLD FROM:-A vertically separation is not allowed. The packages must be horizontally separated by a complete compartment. On deck a horizontal separation of at least 24m is required and between "on deck" & "under deck " package , 24m plus an intervening compartment.


IAMSAR Volume 3. This manual should be carried aboard rescue unit