How Compressed Air Helps in Starting a Diesel Engine of a Vessel

Do you know how diesel engines are started in ships? Equivalent in size to a four-story building, the main propulsion engine is started with the help of compressed air at a pressure of 30 bar. Where a ship gets its compressed air supply from?

Cruise Vessels
Air is a natural resource that is available in plenty and free of cost. It has a very important part in starting the engine of a vessel. Supply of compressed air is required to start diesel engines. This compressed air is passed on into the cylinders in the right order for the direction needed. A supply of compressed air is preserved in the air reservoirs present in the ships or ‘bottles’ for instant use. Usually, the stored compressed air facilitates up to 12 starts. The air system is engineered with interlocks to prevent starting if other parts of the engine are not in order.

The compressed air to the air receivers is supplied by air compressors. The compressed air is further passed on by a huge air pipe to a remotely operating automatic or non-return valve. Then it is supplied to the cylinder air start valve. Once the cylinder air start valve is opened, it will allow compressed air into the cylinder.

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Starting issues in a diesel engine of a vessel

Starting an engine during the colder months is really difficult. Besides, the lubricating oil that is used for running the engine remains in a very hot state and viscous. But the same oil gets very sticky and thickened when the engine is in stopped mode. The engine movement implies that the entire piston has to move up side and down within the engine cylinder which also comprises cold lubricating oil and gives much resistance. Using batteries is not a very practical idea because the power required to rotate such an engine is beyond imagination. It will require an army of batteries to get the result. In such a scenario, the role of the compressed air comes into action.

Role of compressed air:

  • Starting the main propulsion engine
  • Starting auxiliary diesel engine
  • Blowing vessels’ whistle
  • Cleaning and general service for engine room

The compressed air has a crucial role in ships. Every ship is equipped with a “The First Start” or “Dead-Start” mechanism. When the vessel is completely ‘dead’ i.e. no power or no machines are running and no compressed air in the reservoir to start the auxiliary diesel engine, then an alternative is kept in every vessel  to fill up the air bottle or reservoir to bring back the normal  and safe working condition of the ship. This is offered by either an “Emergency Air Compressor” run by an electric motor or a small diesel engine which gets its power supply from “Emergency Generator”.

The “General Average” Rules in Maritime Industry

“General Average” is a phrase used in the marine industry to describe shares in a common loss at the time of accidents. According to the rule, the distribution of losses between the parties caught up in any maritime adventure in the event of an unusual sacrifice or if the expenses are made deliberately with proper explanation that the causes involved preserving other property from risk of being misplaced or lost.

The sections of General Average under the York Antwerp Rules 1994 has been simplified and presented in this write-up. These are:

  • When a loss is deemed

A loss under general average is considered only if the sacrifice is logically made for the intention of preserving the property involved as a matter of common safety or reason of sacrifice is extraordinary. For example – Capsize due to stormy weather condition, shifting of cargo resulting in unnecessary listing of vessel.

  • Preserving the cargo or vessel

When two or more than two vessels are used for commercial purposes and are towing or pushing, then general average is applicable if the vessels get disconnected from one another to protect the vessel and the cargo.

  • Risk is equal in each party’s share

The share of each party under general average should not be set on using a faulty approach. The risk created by all should be same in every aspect. If the action of one party has led to the loss, legal steps can be taken for those actions.

  • Claims due to delay

General average is applicable only for those losses that are directly connected with the value of the cargo or the vessel. Any claims crop up due to the delay, expense or loss occurring due to market loss or any other loss should not be considered into general average.

  • When a vessel or cargo is damaged

If cargo or vessel is damaged by water, which also includes sinking a burning vessel to put off the fire, then that damage will also be considered under general average. Besides, if a vessel is ashore deliberately for general safety, it excludes damages caused by fire or heat.

  • Salvage Operations

If salvage operations are performed in order to prevent or save the loss of cargo, or to reduce or prevent an environmental damage, the expenses implicated and the remuneration to salvors should be counted in general average

  • When cargo is sold in damaged condition

If the selling of the cargo is initiated when it is damaged, the general average amount is the subtraction between the net damaged value and net sound (undamaged) value.

If you are looking to know more in detail, ship broker companies in Norway can help you out.