CHAPTER 3: Ports and Harbor

This contains the terms and definitions related to Chapter 3: Ports and Harbor

Swell

Wind generated waves that are created in the deep ocean at some distance from the port site, and the wind that created them may be too distant to be felt in the port and may have changed its direction by the time the waves reach the port.

Long waves

Waves which have a very long period

Deep water waves

Those which occur in water having a depth greater than one-half of the wave length.

Seiche

A phenomenon involving abnormal oscillations of the water level with a period of approximately a few minutes to a few tens of minutes.

Astronomical tide

The periodic rise and fall of sea level in response to the gravitational attraction of the sun and moon as modified by the earth's rotation. 

Dredging

The process of widening, enlarging, cleaning, or deepening of channels in harbors, rivers and canals to maintain the ideal depth of berthing areas due to fast siltation rate.

Clapotis

The pressure against a vertical wall due to waves.

Steepness

The ratio of the wave height to its wavelength.

Wave Period

The interval of time between successive crest of the water waves passing a stationary point of reference.

High Water

The maximum height reached by each rising tide.

High Water Lunitidal Interval of the Place

The average time interval, in solar hours and minutes from a lunar transit to the next succeeding high water at a given place as determined by an extended set of observations.

Low Water

The maximum depression of the falling tide.

Slack Water

The period during which the current is negligible while it is changing directions.

Flood Current

The tidal current setting into the bays and estuaries along the coast.

Port

It is a harbor in which terminal facilities are provided.

Fairway

An open water of navigable depth.

Wave Refraction

A change in the dissection of travel of the wave with change in depth of water which distributes wave energy along the seashore unevenly.

Wind Waves

Waves generated by wind that are acting on the sea surface bordering on the port site.

Swell Waves

Wind generated waves which are created in the deep ocean at some distance from the port site and the wind that created them may be too distant to be felt in the port or may have stopped blowing or changed, its direction by the time the wave reach the port.

Seiching Waves

Waves of this type have very long periods, typically from 30 sec. up to the tidal period of 12 hr. 25 min. and are mostly found in enclosed or semi-enclosed basins such as artificial port basins or bays.

Tsunamis

Waves with an extremely long period that mainly occur when there is a sudden large scale sea floor movement associated with severe, shallow focus earthquake.

Intermediate Water Waves

Waves in which the ratio of water depth to the wave length is less than 0.50 but greater than 0.40.

Significant Wave Height

The arithmetical mean value of the highest, one-third of the waves for a stated interval.

Semi-Diurnal Tides

Tides that occur twice its lunar day.

Tidal Bores

High crested waves caused by the rush of flood tide up a river or by meeting of tides.

Wind

The circulation of masses of air more or less parallel to the earth's surface.

Monsoon

Prevailing winds which are seasonal blowing in one direction over part of the year and in the opposite direction the remainder of the year.

Windward Side

The side of a structure facing the direction from which the wind comes.

Leeward Side

The opposite side of a structure facing the direction from which the wind comes.

Wind Rose

The graphical representation of the direction, frequency and intensity of winds at a particular location over a period of time.

Velocity of Wave Propagation

The speed of the waveform which travels over the water surface for a certain wave period.

Shallow water waves

Waves in which the ratio of water depth to the wavelength is equal to or less than 0.40.

Beuforts Scale

An instrument used to measure the intensity of wind.

Wind waves

Waves generated by wind that are acting on the sea surface bordering on the port site.

Steepness

The ratio of the wave height to its wavelength.

Storm surge

An abnormal rise of the sea level that occurs when a typhoon passes by. This rise above normal level on this open coast is due to atmospheric pressure reduction as well as due to wind stress.

Wave period

The interval of time between successive crest of the water waves passing a stationary point of reference.

High water

The maximum height reached by each rising tide.

High water lunitidal interval of the place

The average time interval, in solar hours and minutes from a lunar transit to the next succeeding high water at a given place as determined by an extended set of observations.

Low water

The maximum depression of the falling tide.

Slack water

The period during which the current is negligible while it is changing directions.

Flood current

The tidal current setting into the bays and estuaries along the coast.

Mean Low Water

The average height of all low waters at any place over a sufficiently extended period of time.

Length of Wave for Long Waves

Waves with a relatively long wave length compared to the water depth d < 1/25 are called long waves.

Lee Side

The harbor entrance should, if possible, be located on the harbor.

Diurnal Range

The difference in height between the mean higher high water and the mean lower low water.

Neap Tide

When the lines connecting the earth with the sun and the moon form a right angle, that is the moon is in her quarters, then the actions of the moon and sun are subtractive, and the lowest tides of the month occur.

Amplitude

The height between the trough and the crest of a wave.

Astronomical Tidal Day

The time of rotation of the earth with respect to the moon and the planets, which is approximately 24 hours and 50 minutes.

Gravity Waves

Waves are formed by the frictional drag of wind across the water surface. This process transfers energy from the wind to the water. As wind moves water particles from their original positions, gravity acts as a restoring force, returning the particles to their original state.

MLLW

The datum line for design of port facilities in accordance with charts, which is being used by the Phil. Ports Authority (PPA).

Tidal Range

The difference in height between high water and low water at a tidal station.

Age of Tide

Owing to retardation of the tidal wave in the ocean by frictional force, as the earth revolves daily around its axis and as the tide tends to follow the direction of the moon, the highest tide for each location is not coincident with conjunction and opposition but occurs at some constant time after new and full moon. This interval which may amount to as much as two and a half days.

Diffraction

The spread of energy along a wave crest.

Duration

Time that a wind blows across the water.

Mean High Water

The average of the high water over a 19-year period.

Diurnal Tides

Tides which occurs only one high tide a day.

Mixed Diurnal Tides

If one of the two daily tide is incomplete, that is it does not reach the height of the previous tide, then the tides.

Wharf

A dock which is parallel to the shore, which can be used for docking on one side only.

Pier

A dock which projects into the water, which may be used on docking for both sides.

Dry dock

An artificial basin for vessels when the basin is pumped out.

Groin

A dock which is similar to a wharf and often referred to as such, is backup by ground as it derives its name from the very nature or supporting ground in the back of it.

Dolphins

Marine structures for mooring vessels.

Breasting Dolphins

Type of dolphins which are designed to take the impact of the ship when docking and to hold the ship against a broadside wind. Therefore, they are provided with fenders to absorb the impact of the ship and to protect the dolphin and the ship from damage.

Mooring Dolphins

Type of dolphins which are not designed for the impact of the ship, as they located in back of the face of the dock where they will not be hit. They are located about 45° off the bow and stern.

Fixed mooring berth

A marine structure consisting of dolphins for tying up the ship and a platform for supporting the cargo handling equipment.

Mole

A breakwater is a structure constructed for the purpose of forming an artificial harbor with a water area so protected from the effect of sea waves as to provide safe accommodations for shipping. When a breakwater supports a roadway, this is called:

Bollard

It is the mooring fitting for mooring ships during a storm installed at the outside or outside/inside of the berth far from the water line.

Bitt

It is installed close to the waterline of the berth to be used for mooring ships in ordinary condition.

Single and Double Pillar

Mooring applications where mooring ropes are not pulled at steep angles. Single pillar type should preferably be allocated to lines from one ship only.

Tee-head Bollard

Bollard with a “T” shape, suitable for general mooring including steep rope angles. Allows multiple lines to be secured in different directions.

Sloping Lobe Bollard

A type with sloped ropes on each side. Ideal for situations with steep rope angles and allows lines to be attached without interference. It has a normal maximum capacity of 200 tons.

Tee-head

All general mooring applications including steep rope angles. Any one bollard should preferably be allocated to lines from one ship only.

Tee-head shape

It is when bollards are pulled upward.

Bollard

Mooring fitting for mooring ships during a storm installed at the outside or outside/inside of the berth far from the water line.

Bitt

Mooring fitting for mooring ships during a storm installed close to the water line of the berth.

BREAKWATER

The structure that protects the harbor from stormy waves and permits calm in the harbor is called:

QUAY

A platform built in the harbor parallel to the shore and backed up by ground is called.

WHARF

A platform built parallel to the shore or breakwater within the harbor to berth vessels is called:

BULKHEAD

A structure for retaining or to prevent earth or fill from sliding into water:

BATHYMETRY

The physical configuration of the seabed, the measurements of depths of water in the ocean, etc. and also information derived from such measurement.

BOLLARD

A vertical post to which the eye of a mooring line can be attached.

GROIN

A shore protection structure usually built perpendicular to the coastline to retard littoral transport of sedimentary materials.

JETTY

A berth structure which projects out into the water from the shore, or a berth structure at some distance from the shoreline is called:

PIER

A berth structure projecting out from the shoreline.

PORT

A sheltered place where the ship may receive or discharge cargo. It includes the harbor with its approach channels and anchorage places.

QUAY

A sheltered place where the ship may receive or discharge cargo. It includes the harbor with its approach channels and anchorage places.

RELIEVING PLATFORM

A platform or deck structure built below the top deck level and supported on bearing piles. The main function of the platform is to reduce the lateral soil pressure over the upper portion of the sheet wall.

Sea Island

A berth structure with no direct connection to the shore, at which the ships can berth. Berthing can take place on either one or both sides of the structure.

Breast mooring lines

These are used to reduce the sway and yaw motions and should be perpendicular to the ship.

Spring mooring lines

These are used to reduce the surge motion of the ship along the berth front. They should be as parallel as possible to the berth front. The angle between the berth front and the shipside should be equal to or less than 10°.

Head and stern lines

These can be used in addition to the spring and breast lines to reduce the ship's motion.

Air draft

The maximum distance from the water level to the highest point of the ship at the prevailing draft.

Scantling draft

The draft for which the structural strength of the ship has been designed.

Designed draft

The draft for which the fundamental design parameters of the ship are based.

Squat

The reduction of under keel clearance due to the suction effect induced by the higher current velocity between the sea bottom and the ship.

Trim

The difference between the aft and the forward draft.

Stern

The point at the backend of a ship.

BOW

The point at the front end of the ship.

AFT

The distance from the stern to the midships.