Chapter 8 Flashcards
Maritime shipping is the preferred means of
global transportation of crude oil and petroleum products
Oil shipments account for about
30% of global maritime trade
The most commonly used crude oil shipping routes originate in
the Middle East.
The most commonly used crude oil shipping routes originate in the Middle East:
They pass through the Bab‐el‐ Mandeb Strait, which separates Djibouti in Africa from Yemen in the Arabian Peninsula, or
• The Strait of Hormuz, the world’s main oil shipping lane, which separates the United Arab Emirates and Oman from Iran.
Marine weather forecasts help shipping operators to
plan and schedule work, vessel, crew and other operations more safely and efficiently
An acquaintance with marine meteorology helps the navigator to
make a passage (sea route planning)with the least delay and in comparative safety.
An acquaintance with marine meteorology helps the navigator to make a passage (sea route planning)withtheleast delayandincomparativesafety.
Weather is a key aspect in
planning the best route and preparing for the conditions likely to be experienced en route and at destination ports
Ship weather routing develops
an optimum track for ocean voyages based on forecasts of weather, sea conditions, and a ship’s individual characteristics for a particular transit
Optimum ship routing is
the art and science of developing the “best route” for a ship based on the existing weather forecasts, ship characteristics, and special cargo requirements.
Optimum ship routingis the art and science of developing the “best route” for a ship based on the existing weather forecasts, ship characteristics, and special cargo requirements.
• For most transits this will mean
the minimum transit time that avoids significant risk to the vessel, crew and cargo
For most transits this will mean the minimum transit time that avoids significant risk to the vessel, crew and cargo.
• The goal is not to
avoid all adverse weather but to find the best balance to minimize time of transit and fuel consumption without placing the vessel at risk to weather damage or crew injury
The mariner’s first resources for route planning in relation to weather are
- the Pilot Chart Atlases,
- • theSailing Directions (Planning Guides),and
- • other climatological sources such as historical weather data tables.
• thePilot Chart Atlases,
• theSailing Directions (Planning Guides),and
• other climatological sources such as historical weather data tables.
These publications give
climatic data, such as wind speed and direction, wave height frequencies and ice limits, for the major ocean basins of the world.
Route planning normally will start by
reviewing the appropriate Pilot Chart Atlases and Sailing Directions (Planning Guides) to determine the normal weather patterns, weather risks and prevailing ocean currents
Route planning normally will start be reviewing the appropriate Pilot Chart Atlases and Sailing Directions (Planning Guides) to determine the normal weather patterns, weather risks and prevailing ocean currents.
The Routing Service then
reviews recent weather patterns and weather forecast charts to determine the most likely conditions during the course to the voyage.
A preliminary routing message is transmitted to
the master of a vessel
A preliminary routing message is transmitted to the master of a vessel prior to
departure
A preliminary routing message is transmitted to the master of a vessel prior to departure with a
detailed forecast of expected storm tracks, an initial route proposal and the expected weather to be encountered enroute
A preliminary routing message is transmitted to the master of a vessel prior to departure with a detailed forecast of expected storm tracks, an initial route proposal and the expected weather to be encountered enroute.
• This allows the master to
better plan his route
This allows the master to better plan his route.
• Once the vessel departs, the vessel’s
progress is monitored closely with weather and route updates sent as needed
Pilot Charts
rank near the top as one of the most valuable assets for the long distance cruiser or passage maker.
Pilot Charts rank near the top as one of the most valuable assets for the long
distance cruiser or passage maker.
As an
aid to the navigator
As an aid to the navigator, it provides an
additional tool for voyage planning by allowing a route to be selected that is favorable as to winds, weather, and ocean conditions
Pilot Charts depict in some detail the
prevailing weather patterns including:
- wind directions and speeds,
- • wave heights, ocean currents,
- • visibility, barometric pressures,
- • sea surface temperatures,
- • percentage possibilities for winds of Force 8 or greater, and
- • ice limits to be found in the areas covered for each month of the year.
In ship routing, consideration is given to
wind, seas, fog, ice, and ocean currents
In ship routing, consideration is given to wind, seas, fog, ice, and ocean currents.
While
all of the environmental factors are important for route selection and surveillance, optimum routing is normally considered attained if the effects of wind and seas (wave height)can be optimized.
Wind:
The effect of wind speed on ship performance is difficult to determine
Wind:The effect of wind speed on ship performance is difficult to determine.
• In light winds
(less than 20‐knots), ships lose speed in headwinds and gain speed slightly in following winds.
In light winds (less than 20‐knots), ships lose speed in headwinds and gain speed slightly in following winds.
• For higher wind speeds
ship speed is reduced in both head and following winds.
For higher wind speeds, ship speed is reduced in both head and following winds. This is due to
the increased waveaction, which even in following seas results in increased drag from steering corrections, and indicates the importance of sea conditions in determining ship performance
Wave Height:
Wave height is the major factor affecting ship performance
Wave Height:Wave height is the major factor affecting ship performance.
• Wave action is responsible for
ship motions
Wave action is responsible for ship motions which
reduce propeller thrust
Wave action is responsible for ship motions which reduce propeller thrust and cause
increased drag from steering corrections
The relationship of ship speed to wavedirection and height is similar to
that of wind
The relationship of ship speed to wavedirection and height is similar to
that of wind. Head seas
reduce ship speed
The relationship of ship speed to wavedirection and height is similar to
that of wind. Head seas reduce ship speed, while following seas
increase ship speed slightly to a certain point, beyond which they retard it
In addition to the above, the …………………………………………. should be considered for ship routing
synoptic weather conditions
In addition to the above, the synoptic weather conditions such as mentioned
below should be considered for ship routing:
- The effect of weather and seas associated with extratropical low pressure systems and the tropical systems.
- Seasonal or monsoon weather is also a factor in route selection and diversion in certain areas
