Marine Anemometer - Working principle and Types

"Marine Anemometer"

The Marine Anemometer is a weather instrument used to measure wind speed and wind direction. The term anemometer is derived from the Greek word "anemos" meaning wind.

There are 2 mainly used anemometer in the marine industry.

Cup anemometer
Vane anemometer

Cup anemometer:

Working principle:

Cup Anemometer consists of 4 Hemispherical cups mounted on the end of the horizontal arms.
Horizontal arms are mounted on a Vertical shaft.
The airflow passes through the cups in a horizontal direction makes the shaft rotate.
AC generator connected to the shaft. Faster the shaft rotates higher the electric current will produce.
AC voltage is rectified to DC voltage and output voltage is measured for set interval and the voltage signal is calibrated to measure the wind speed.
This type of anemometer gives only wind speed unless the wind vane additionally fitted on the instrument for wind direction.

Vane Anemometer:

Working principle:

In Vane Anemometer the propeller is fitted, the rotating axis of the propeller must be parallel to the flow of wind.
To align the body parallel to the wind flow, the tail (wind vane) is designed. so the propeller always faces the wind direction.
AC generator connected to the shaft. Faster the shaft rotates higher the electric current will produce.
AC voltage is rectified to DC voltage and output voltage is measured for set interval and the voltage signal is calibrated to measure the wind speed.
An analog signal is transmitted to the wind speed and direction indicator and the instantaneous wind speed and wind direction are ascertained.

When to Condemn(remove) wire rope from use + Numericals

"Condemn" means disapproval, unacceptable.

A wire rope should be inspected before use to detect any of the above conditions so that its suitability (strength) may be estimated.

The "Docks Regulations 1934" require that a wire rope be condemned if in any length of 8 times its diameter, the total number of visible broken wires exceeds 10% of the numbe of wires in the rope or the rope shows signs of excessive wear, corrosion or other defect which in the opinion of the person who inspects it, renders it unfit for use.

The explanation for the above statement:

If 10% or more from the total number of wires is found broken in the length of (8 x dia) of the wire rope is condemned.

Example:

In 6x12 wire rope, dia 15mm has 10 broken wires.

Ans:

Total number of wires => 6x12 = 72 wires

Inspection length (8 times the dia)=> 8x15 = 120mm

10% of total no. of wires => (10x72)/100 = 7.2 wires

*For the inspection length of 120mm, more than 7.2 broken wires are found, then the wire rope needs to be condemned.

*The actual broken wire is 10 wires (exceeded).

∴Yes, The wire rope has to be condemned.

____________________________________

Numericals from Capt. Errol Fernandes book. Pg no. 130

1. State whether you would condemn the wire rope in the following cases

Case ( i )

A 6x24 wire 22mm in diameter has 15 broken wire in a length of 176mm.

Ans:

Total number of wires => 6x24 = 144 wires

Inspection length (8 times the dia) => 8x22 = 176mm

10% of total no. of wires => (10x144)/100 = 14.4wires

*For the inspection length of 176mm, more than 14.4 broken wires are found, then the wire rope needs to be condemned.

*The actual broken wire is 15 wires (exceeded).

∴Yes, The wire rope has to be condemned.

**☁🌤🌫Clouds:🌦🌧⛈**

For Clouds? and Formation of clouds: - Click here

Clouds are classified in 2 ways:

Based on height above sea level
Based on the shape of a cloud

Root words:

For Height:

Cirro => High
Alto => Medium

For Shape:

Cirrus => Thin, white, high
Cumulus => Puffy, rounded, cauliflower structure, white
Stratus => Flat (blanket like), layered

Precipitation:

Nimbus / Nimbo => Rain

Tips for describing the cloud:

See the below picture, this picture tells the story.
If you keep this picture in your mind, then describing the clouds is as easy as ABC.
You can easily make out the HEIGHT, SHAPE, COLOUR, and LOOK of the cloud from this picture.

Let's describe the of clouds from the picture:

Cirrus:

High cloud
White colour
Thin
Looks like feathers or wispy(like eye bro)

Cirrostratus:🌤

High cloud
Flat (blanket like).
Looks like a veil (veil means like see through dress)
eg. 👆 for a veil
This veil produce halos around sun, sufficiently clear for altitude observation.

Cirrocumulus:☁️

High cloud
White colour
Looks like patches of Small puffy or cauliflower

Altostratus:🌥

Medium cloud
Thicker than cirrostratus
Sun or Moon appears very dim - as seen through frosted glass
Eg. 👆Sun or moon seen through frosted glass.
Not clear enough for altitude observation.

Altocumulus:☁️☁️☁️

Medium cloud
White or grey in colour
Have dark shadows
Looks like 👆 flattened globules/rolls/long bands

Stratus:🏔

Low cloud
Even layered
Dark grey cloud
Can obscure the sun completely and weaken daylight

Stratocumulus:☁️

Low cloud
Even layered or patches of globular masses which appear soft
With dark shadows
Form an overcast sky

Nimbostratus:🌧

Low cloud
Dark grey cloud
Can greatly obscure the sun completely and weaken daylight
Looks like uniform and threatening
Can produce moderate rain

Cumulus:🌫

It's base at a low level
White colour
Thick cloud
Flat base and cauliflower-like structure
A dark shadow is seen
Indicate fair weather

Cumulonimbus:⛈

It's base at a low level
Mass grey cloud (heavy cloud)
Have a great vertical extent till tropopause and spread sideways and appears like anvil shape
Threatening appearance
Thunder cloud

What is Cloud?

Clouds are created when water vapor, condenses and turns into liquid water droplets. These water droplets form on tiny particles, like dust, ice crystals, or altogether that are floating in the air, become visible as Cloud.

Clouds are formed in 4 main ways:

Turbulence
Orographic lifting
Convection
Frontal lifting

Clouds formed by Turbulence:

Strong winds blowing over uneven ground strike against the various obstructions and the air gets deflected upwards.
This causes thorough mixing of the air and, as the air rises, and cools adiabatically below its dew point, clouds will form.
These clouds will be of an even, layer type (stratus) and their bases will generally be not more than 600m high.
Turbulence clouds will be formed in great quantities if the air is moisture-laden and blows over cold, uneven ground.
Over the sea, wind speeds of more than 13 knots only (force 4 and over) can produce sea waves of sufficient height to create turbulence clouds.

Clouds formed by Orographic lifting:

Orographic lifting occurs when a mountain acts as a barrier to the wind.
During the air ascends a mountain slope, adiabatic cools below its dew point and forms an orographic cloud.
These are stratus type.
If the mountain is quite high, the further ascent will result in nimbostratus and continuous precipitation.
Precipitation on the windward side while on the leeward side the air is much drier.
Leeward side, while descending air warms adiabatically.
This is called Banner cloud.

Clouds formed by Convection:

Convectional uplift happens when the surface of the air is heated at the ground and expands.
Then the air should be less dense than the surrounding air.
After that, the less dense air will begin to rise and cools adiabatically below its dew point.
When this is successful, convection cloud forms, due to saturation.
The greater the ascent of air, the greater the vertical extent of the cloud resulting in the vertical extent of the towering cumulus.
If ascends rapidly(fast) vertical extent reaches the tropopause and spreads sideways and resembles an anvil-shaped cloud called cumulonimbus.

Clouds formed by Frontal lifting:

Usually, the two masses (warm and cold) of air are opposite temperatures and moistness.
One air mass is hot and moist while the other air mass is cool and dry.
The boundary between them is not vertically.
Then the cool air mass would act as a sloped surface and the warm air mass would use the surface to rise.
The warm air mass rises and cools adiabatically and cools below its dew point.
In case of warm front: Slope is gradual and up sliding warm air forms stratiform clouds - nimbostratus, altostratus, cirrostratus and finally cirrus.
In case of cold front: The slope is very steep and up sliding warm air forms cumulonimbus and cumulus clouds.

UNCLOS

United Nations Convention on the Laws of Seas (UNCLOS) is also known as the Law of the Sea Convention or the Law of the Sea Treaty.
This defines the rights and responsibilities of nations towards the use of the world’s oceans.
The Convention started in 1973 and concluded in 1982, replacing four older treaties of 1958.
UNCLOS came into force in 1994.

"Awesome" Tips to make Passage Plan 🗺️ for 2nd mate examination

Passage planning - [For 2nd mate examination purpose only].

Example of Decent passage planning:👇

Note:

Make the plan intend to safe navigation,
The information included in the chart should benefit the navigator, not to impress the examiner.

Passage plan table:

Note:

The table below is the minimum information that must be included in your passage plan table.
if time permits you can include additional information such as DTG, Min UKC, Position plotting interval (PPI), Position Plotting method (PPM), Speed to maintain, Bridge watch level, etc...

Do's and Don'ts on examination:

Do's:

Plot courses for given [position A to B] or [berth to berth].
Carefully choose the course line that suited for your draft.
Indicate Waypoint number and DTG.
Course to steer and Distance of the leg should be clearly marked. [suggested to write course Bigger than the distance 030 x 5'].
Draw wheel over lines wherever doing sharp alteration.
Draw parallel indexing lines as necessary.
Mark NO-GO areas. [Eg. Areas of obstruction, areas of lesser soundings, area of non-navigable areas, etc.,].
Mark emergency anchorage. ( make sure no foul ground, explosive dumping ground, submarine cables, or pipelines ).
Pass the correct side of the cardinal marks.
Pass the correct lanes of TSS.
Include the notes as required - ( make it short and readable)
Additionally, information included in the plan should benefit the navigator, should not hamper the chart info.

Don'ts:

Never include unwanted information in a chart. [Eg. Writing Waypoint lat/long in the chart, it will only hamper the chart info, it doesn't help the officer in any way].
Do not pass over the wrecks.
Wheel over lines is not necessary for small alteration.
Do not mark NO-GO extensively. [Eg. Vessel is on south coast of India bound to Singapore, in this do not mark whole Srilanka as no go area 😠].

THE HARMONIZED SYSTEM OF SURVEY AND CERTIFICATION (HSSC)

HARMONIZED SYSTEM OF SURVEY AND CERTIFICATION (HSSC)

The HSSC is an IMO system, came into force in the year 2000.
Earlier that Ship statutory certificates are issued on different dates which are similar to the date of each individual initial survey, also they have different period of validity.
(e.g. survey for load line or cargo ship safety construction is almost the same procedure and areas to be surveyed, only with little difference between them). If a ship undergoes a Load line survey, the survey of Ship safety construction will only overlap.
This put the Ship officers under pressure to prepare the vessel for survey all the time and certifying authorities also have to board the vessel for survey several times during the course of the year.

To avoid the extra effort, HSSC "harmonized" (simplified and better organized) the survey procedures and "uniformity" for survey dates for all major ship certificates.

The features of HSSC are:

All certificates that fall under this system will be issued on one date only so that all annual and other surveys for each certificate will fall on the same dates.
There will be a 1-year standard interval between surveys.
A maximum period of validity of 5 years for all certificates for cargo ships.
A maximum period of validity of 12 months for the Passenger Ship Safety Certificate.
A 3-month extension of the certificate is possible for the ship to complete its voyage (1 month for ships engaged in short voyages). The new certificate will start from the date of expiry of the existing certificate before extension.
A combined cargo ship safety certificate may replace the existing certificates as follows:

Cargo Ship Safety Equipment Certificate.
The Cargo Ship Safety Radio Certificate.
The Cargo Ship Safety Construction Certificate

No more unscheduled inspections for harmonized system of classification for ships, while annual surveys have been made mandatory.

Types of survey

The first survey which a ship undergoes is always the Initial Survey (I). The date of completion of ALL the surveys is the date of issue of each certificate. Frequency= (before the ship put into service)

An Annual survey (A) is a general inspection of the items relating to the particular certificate to ensure that they have been maintained and remain satisfactory for the service for which the ship is intended. Frequency=(should be held within 3 months before or after each anniversary date of the certificate).

An Intermediate survey (In) is an inspection of specified items relevant to the particular certificate to ensure that they are in a satisfactory condition and fit for the service for which the ship is intended. Frequency=(should be held within 3 months before or after the 2nd-anniversary date or within three months before or after the 3rd-anniversary date of the appropriate certificate and should take the place of one of the annual surveys).

A Periodical survey (P) is an inspection of the items relating to the particular certificate to ensure that they are in a satisfactory condition and fit for the service for which the ship is intended. Frequency=(should be held within 3 months before or after the 2nd-anniversary date or within 3 months before or after the 3rd-anniversary date in the case of the cargo ship safety equipment certificate and should take the place of one of the annual surveys; in the case of the cargo ship safety radio certificate, it should be held within 3 months before or after each anniversary date.)

A Renewal survey (R) is the same as a periodical survey but also leads to the issue of a new certificate. Frequency=(should be held before the appropriate certificate is renewed. The cargo ship safety construction renewal survey may be commenced at the fourth annual survey and maybe progressed during the succeeding year with a view to completion by the 5th-anniversary date).

An Additional survey (Ad) is carried out Whenever an accident occurs to a ship or a defect is discovered which affects the safety or integrity of the ship which is reported to administration by the master or owner of the ship. Frequency=(when required after an investigation; or whenever any important repairs or renewals are made; or when ballast water management systems (BWMS) are retrofitted on an existing ship to which an International Ballast Water Management Certificate was previously issued).

At least two inspections of the Ship’s bottom (B) are to be carried out in a period of 5 years, with a maximum interval between the two inspections to not exceed 36 months.

List of the survey in conventions and codes:

SOLAS 1974 as modified by its 1988 protocol
LLC 1966 as modified by its 1988 protocol
MARPOL 1973 and 1978 as further amended by 1997, as amended (MARPOL)
BWM convention 2004, as amended (BWM Convention)
IBC Code
IGC Code
BCH Code
POLAR Code

List of statutory certificates required on board ship relating to harmonized system of survey and certification (some depend on the type of ship) with codes:

(E) Cargo Ship Safety Equipment Certificate;

(C) Cargo Ship Safety Construction Certificate;

(R) Cargo Ship Safety Radio Certificate;

(L) International Load Line Certificate;

(O) International Oil Pollution Prevention Certificate;

(N) International Pollution Prevention Certificate for Carriage of Noxious Liquid Substances in Bulk;

(S) International Sewage Pollution Prevention Certificate;

(A) International Air Pollution Prevention Certificate;

(D) International Certificate of Fitness for the Carriage of Dangerous Chemicals in Bulk or the Certificate of Fitness for the Carriage of Dangerous Chemicals in Bulk;

(G) International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk;

(P) Passenger Ship Safety Certificate;

(W) Polar Ship Certificate;

(B) International Ballast Water Management Certificate;

THE HARMONIZED SYSTEM OF SURVEY AND CERTIFICATION
DIAGRAMMATIC ARRANGEMENT

IMO Link: Click here

Understanding of Propellers and its definitions 🌀

What is Propeller?

A propeller is a rotating shaft with a twisted blade attached to it which is used to propel the ship using power generated and transmitted by the main engine.

Types of propeller:

By number of blades:

3 Blade propeller

4 Blade propeller

5 Blade propeller

3 blade and 4 Blade propellers are mostly used on ships

By pitch of the propeller:

Fixed pitch propeller
Controlled pitch propeller

Lets see what is Fixed and Controlled pitch propeller:

Fixed Pitch Propeller:

Propellers of the Fixed Pitch type are cast in one block and normally made of a copper alloy. The position of the blades, and thereby the propeller pitch is fixed and that cannot be changed in operation.

Controlled Pitch Propeller:

A controllable pitch propeller (CPP) or variable pitch propeller is a type of propeller with blades that can be rotated around their long axis to change their pitch using a means of mechanical or hydraulic arrangements.
If the pitch can be set to negative values, the reversible propeller can also create reverse thrust for going backwards without the need of changing the direction of shaft revolutions.

Propellers and definitions:

Blade Face

Pressure Side, Pitch Side. Aft side of the blade when viewed from aft (surface facing the stern).

Blade Back

Suction side. Forward side of the blade when viewed from aft (surface facing the bow).

Blade Number

Equal to the number of blades on the propeller.

Blade Root

Fillet area. The region of transition from the blade surfaces and edges to the hub periphery. The area where the blade attaches to the hub.

Blade Tip

Maximum reach of the blade from the centre of the hub. Separates the leading and trailing edges.

Boss or Hub

Solid cylinder located at the centre of the propeller. Bored to accommodate the engine propeller shaft. Hub shapes include cylindrical, conical, radius, & barrelled. Propeller blades are attached to it.

Leading Edge

The edge of the propeller blade adjacent to the forward end of the hub. The leading edge leads into the flow when providing forward thrust.

Trailing Edge

The edge of the propeller adjacent to the aft end of the hub. When viewing the propeller from astern, this edge is closest. The trailing edge retreats from the flow when providing forward thrust.

Rotation

When viewed from the stern (facing forward): Right-hand propellers rotate clockwise to provide forward thrust. Left-hand propellers rotate counter-clockwise to provide forward thrust.

Pitch

Pitch is defined as the theoretical forward movement of a propeller during one revolution assuming there is no "slippage" between the propeller blade and the water. Pitch is the second number listed in the propeller description.

Slip

Slip is the difference between actual and theoretical travel of the propeller blades through water. A properly matched propeller will actually move forward 80 to 90 per cent of the theoretical pitch.

Diameter

Diameter is the distance from the centre of the hub to the tip of the blade x 2. It can also be looked at as the distance across the circle that the propeller would make when rotating. It is the first number listed when describing a propeller.

Radius

The distance from the axis of rotation to the blade tip. The radius multiplied by two is equal to the diameter.

Rake

Rake is the degree that the blades slant forward or backwards in relation to the hub. Rake can affect the flow of water through the propeller.

Aft Rake helps to trim the bow of the boat upward, which often results in less wetted surface area and therefore higher top end speed.

Forward, or negative rake, helps hold the bow of the boat down. This is more common in workboat type applications.

Skew

The transverse sweeping of a blade such that when viewing the blades from fore or aft shows an asymmetrical shape

Aft Skew: Positive skew. Blade sweep in the direction opposite of rotation

Forward Skew: Negative skew. Blade sweep in the same direction as rotation.

Bow thrusters:

Bow thrusters are type of propellers, which are smaller in size and which help in better maneuverability of the ships at lower speeds. They are generally used for maneuvering the vessel near the coastal waters or while entering or leaving a port. Bow thrusters help in assisting tug boats in berthing the ship without wasting time.

Stowage and Segregation of IMDG Cargo

Stowage of IMDG cargo

Stowage means proper placement of cargo onboard a ship in order to ensure safety and Environment protection.
Stowage on deck means stowing on weatherdeck.
Stowage under deck means any stowage that is not in weatherdeck.
Storage requirement assigned through stowage category in column "16A" of dangerous goods list.
These categories define whether the storage categories shall be on Deck or under deck and in some cases stowage in a particular space or type of vessel may be prohibited.
There are separate categories for (class 1 goods) and (class 2 to 9 goods).

IMDG Code stowage and Segregation rules for dangerous goods vessels are categorized into two types, Cargo Ships, and Passenger Ships.

For Class 1: Explosives, Cargo ships (up to 12 passengers), and Passenger ships.

For Class 1 categories are 1 to 5

CTU means closed cargo transport unit.

For Class 2-9: Cargo ships or passenger ships carrying a number of passengers limited to not more than 25 or to 1 passenger per 3 m of overall length and Other passenger ships in which the limiting number of passengers is exceeded.

For Class 2-9 categories are A to E

Work and rest hours requirement as per "MLC 2006" and "STCW 2010"

Work and rest hours requirement:

As per MLC 2006:

Working hours not more than 14 h in any 24 h period, 72 h in any 7 day period or
Hours of rest not less than 10 h in any 24 h period and 77 h in any 7 day period.
The 10 hours of rest may be divided into two periods, one being at least 6 h.

As per STCW 2010:

Hours of rest not less than 10 h in any 24 h period and 77 h in any 7 day period.
The 10 hours of rest may be divided into two periods, one being at least 6 h.
Interval between consecutive periods of rest not to exceed 14 h.
Above need not be maintained in emergencies or in other overriding operational conditions. A minimum disturbance of rest due to drills and must not induce fatigue.
Compensatory rest required when disturbed during UMS watches.
Exceptions may allow for rest hours not less than 70 h in any 7 day period and exceptions not allowed for more than two consecutive weeks. Period between two exceptions not to be less than twice the duration of the exception.
Exceptions permit the 10 hours of rest to be divided into three periods, one being at least 6 h and other two periods being not less than 1 h each. Interval between consecutive periods of rest not to exceed 14 h. These exceptions shall not extend beyond two 24 h periods in any 7 day period.
Administrations shall require that records of daily hours of rest of seafarers be maintained in a standardized format, in the working language or languages of the ship and in English, to allow monitoring and verification of compliance with the provisions of this section. The seafarers shall receive a copy of the records pertaining to them, which shall be endorsed by the master or by a person authorized by the master and by the seafarers.

Maritime Labour convention ( MLC 2006)

MARITIME LABOUR CONVENTION (MLC) 2006

The Maritime Labour Convention (MLC) is an International Labour Organization (ILO) convention, number 186, established in 2006 as the fourth pillar of international maritime law. The other pillars are SOLAS, STCW, and MARPOL.

BRM - "BRIDGE RESOURCE MANAGEMENT" Complete notes

What is BRM?

Bridge resource management [BRM] was adopted in the 1990’s by the maritime industry as a safety and error management tool.
BRM is the effective management and utilization of all resources including equipment, information, and manpower, available to the bridge team, so as to ensure safe completion of the voyage.
By using all available information and assistance it ensures that navigators take the best possible decisions, and that those inevitable human mistakes are captured and mitigated before they can cause any harm.
BRM reduces the risk of marine casualties by helping a ship’s bridge crew anticipate and correctly respond to their ship’s changing situation.
It will thus ensure safer and more efficient operations by blending technical skills and manpower.
BRM also requires the organization and management of operational tasks on board while also satisfying international and local regulatory requirements.
The many elements of job effectiveness and safety, such as individual, organizational, and regulatory factors must be anticipated and planned for.
BRM begins before the voyage with the passage plan and continues through to the end of the voyage with the passage debriefing.
For this reason, Masters’ standing orders require him/her to be called at the earliest indication of a problem, to help strengthen the team.

"EASY" Ship constructions drawings

👍Thumb rule for ship construction diagram:

Different books show a different diagram for the same type of ship, so understand the structural members of that particular type of ship and draw the structural member reasonably and label it.
Eg,. the container ship has BOX GRIDER(Torsion box), mostly Bulk carriers have hopper tanks, oil tankers are double hull, etc,.
Labeling the structures is very important than the drawing, so label as many as you can
You will find some common labeling for all types of ships like deck longitudinals, side frames, center girder, side girder, brackets, lighting hole, etc,. fill the diagram with labels, which is the key to score maximum marks.

MIDSECTION OF GENERAL CARGO SHIP

Diagram 1

Diagram 2

MIDSECTION OF CONTAINER SHIP

MIDSECTION OF BULK CARRIER OR ORE CARRIER

Single skin bulk carrier

Diagram 1

Diagram 2

Typical drawing of Bulk carrier

MIDSECTION OF VLCC

Diagram 1

Diagram 2

MIDSECTION OF DOUBLED-HULLED PRODUCT TANKER

Diagram 1

Diagram 2

MIDSECTION OF OBO CARRIER

MIDSECTION OF TYPE 'B' LNG/LPG CARRIER

INDEPENDENT SELF SUPPORTING SPHERICAL TANK

MIDSECTION OF FULLY REFRIGERATED PRISMATIC TANK

LNG CARRIER

MIDSECTION OF INDEPENDENT TANK OF TYPE C

MIDSECTION OF RO-RO

FOREPEAK TANK AND ITS ARRANGEMENT

Click this link for PANTING ARRANGEMENTS

AFT PEAK TANK AND ITS ARRANGEMENT

CORRUGATED BULKHEADS

Longitudinal bulkheads are horizontally corrugated

Transverse bulkheads are vertically corrugated

TYPES OF RUDDERS

BALANCED RUDDER:

When 25% to 30% of the rudder area is forward of thE turning axis there is no torque on the rudder stock at certain angles and such an arrangement is therefore known as a 'BALANCED RUDDER'.

UNBALANCED RUDDER:

A rudder with all of its area, aft of the turning axis is known as ‘UNBALANCED RUDDER’.

SEMI-BALANCED RUDDER:

A rudder with a small part of its area, less than 20%, forward of the turning axis is called 'SEMI-BALANCED RUDDER'.

STERN TUBE - OIL COOLED

Diagram 1

Diagram 2

STERN TUBE - SEA WATER COOLED

Diagram 1

Diagram 2

BILGE KEEL