25 December 2016
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Marine
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Ship Launching Risk
Shipbuilding Insurance (Builders' Risks Insurance) guarantees the risks that may occur in connection with the construction or construction of ships from laying of keel to completion, including the risk of launching (sea trials), until the delivery of the ship to the principal at the port of destination (delivery to owners).
Building a ship is an ambitious project for a naval architect and shipyard. Other than its enormous value, the name of the designer will always be attached to the image of the ship he/ she made. We are all certainly familiar when we hear the name Thomas Andrew. Yes, this naval architect is famous because the R.M.S Titanic sank in the North Atlantic Ocean as a result of hitting an iceberg.
Given this enormous value, in a series of shipbuilding there are always two ceremonies. First, the keel laying and the most festive is the ship launching. This ship launch is a proud moment as well as the climax of a ship building process. Just imagine, a ship that was built billions of rupiah with hard work and a high level of care and precision could be "destroyed" if there is a failure during the launch. The fate of a new ship is determined in just a few minutes
Given this enormous value, in a series of shipbuilding there are always two ceremonies. First, the keel laying and the most festive is the ship launching. This ship launch is a proud moment as well as the climax of a ship building process. Just imagine, a ship that was built billions of rupiah with hard work and a high level of care and precision could be "destroyed" if there is a failure during the launch. The fate of a new ship is determined in just a few minutes
Get to know the characteristics of the dock type to understand the risk of launching.
1. Graving Dock
In general, this pool dock is owned by a large shipyard which has a large area and is directly facing sea water. Advantages of Graving Dock:
- Safe
- Long service life
- Maintenance costs are quite low
- Can be used for building new ships
Disadvantages of Graving Dock:
- The construction cost is high
- Permanent / cannot be moved
- Location / place matters a lot
- Limited capacity
Ship launching in the graving dock is easy and safe. When sea water is entered through the dock door, the hull will slowly float. If the water level of the pool is the same as the sea level, then the ship can be launched by pulling it using a tug boat out of the dock.
- Safe
- Long service life
- Maintenance costs are quite low
- Can be used for building new ships
Disadvantages of Graving Dock:
- The construction cost is high
- Permanent / cannot be moved
- Location / place matters a lot
- Limited capacity
Ship launching in the graving dock is easy and safe. When sea water is entered through the dock door, the hull will slowly float. If the water level of the pool is the same as the sea level, then the ship can be launched by pulling it using a tug boat out of the dock.
2. Slip Way atau Heeling Dock
The slip way is usually used by shipyards that have a border with a very wide shoreline. Launching on this type of dock makes use of tilt and gravity. There are two methods of launching depending on the type of slip way.
a. Side launching
The ship is launched sideways. This type of launching is very risky and occurs most often due to ship stability. The ship will immediately move freely depending on the lift from the sea water as soon as the hull touches the water. All kinds of preparations related to stability must be considered accurately..
b. Longitudinal launching
This is the same case as side launching, only that this type of launching is carried out lengthwise with the stern of the ship touching the surface of the water first.
In shipbuilding design, there are special calculations for launching using longitudinal launching. The finished ship is placed on a trolley equipped with wooden blocks as supports. This trolley rests on an inclined runway rail and juts into the sea water. In simple terms there are four phases:
- The first phase begins when the ship begins to descend and ends when the ship's center of gravity is directly above the end of the runway. The force acting on the ship is the weight and friction force of the anvil reaction. The ship will move at a speed proportional to the inclination of the runway.
- The second phase begins with the ending of the first phase and ends when the hull hits the water. The force acting on the ship is still the weight of the ship and the lift from the sea water. The ship makes a straight motion along the runway and slowly a lift force emerges from the stern of the ship which has been submerged in water.
- The third phase begins with the ending of the second phase and ends when the skate/ trolley leaves the runway. The force acting on the ship are gravity, buoyancy and water resistance. The ship continues to move straight but can move freely according to the stability of the ship.
- The fourth phase begins with the ending of the third phase and ends when the ship stops moving. The forces that work are the ship's gravity, buoyancy and water resistance.
- The first phase begins when the ship begins to descend and ends when the ship's center of gravity is directly above the end of the runway. The force acting on the ship is the weight and friction force of the anvil reaction. The ship will move at a speed proportional to the inclination of the runway.
- The second phase begins with the ending of the first phase and ends when the hull hits the water. The force acting on the ship is still the weight of the ship and the lift from the sea water. The ship makes a straight motion along the runway and slowly a lift force emerges from the stern of the ship which has been submerged in water.
- The third phase begins with the ending of the second phase and ends when the skate/ trolley leaves the runway. The force acting on the ship are gravity, buoyancy and water resistance. The ship continues to move straight but can move freely according to the stability of the ship.
- The fourth phase begins with the ending of the third phase and ends when the ship stops moving. The forces that work are the ship's gravity, buoyancy and water resistance.
Of the four phases above, the crucial point is in phase three, when the bow part of the ship (or the bulb bow if any) is still resting on the trolley and the glide, while the sea water is insufficient or suddenly the water recedes, therefore the submerged hull does not provide a perfect lift power. Therefore the stability of the ship is corrupt and is possible to capsize the ship.
c. Floating Dock
Floating Dock is a construction in the form of pontoon which is equipped with crane lifting, water pumps and mooring equipment.
The way this dock works is by drowning it by filling the pontoon with sea water until it sinks below the surface of the water. The ship is placed on it and then the water in the pontoon is thrown back to lift the ship above the water surface. Vice versa, when the ship is about to be launched, the pontoon is immersed until the ship moves freely on the surface of the water. This floating dock is usually only used for repair with a relatively small vessel size, but can move places.
d. Open Docking
Most of the new shipyards in Indonesia currently use this type of dock. Beside it not requiring a special place, the investment costs are relatively cheaper. Ships of any type can be built at this shipyard depending on the capacity of the equipment they have. The launch method used is also very simple, namely using a marine air bag.
In practice it is very similar to the slip way using longitudinal launching, except that the trolley and rail are replaced by an air bag. The number and position of air bags are adjusted to the dimensions of the ship and the distance of the ship from the shoreline. Launching using an air bag does not really depend on the tidal conditions of the sea water.
In practice it is very similar to the slip way using longitudinal launching, except that the trolley and rail are replaced by an air bag. The number and position of air bags are adjusted to the dimensions of the ship and the distance of the ship from the shoreline. Launching using an air bag does not really depend on the tidal conditions of the sea water.
From the several launching methods above, the type of slip way dock that has the greatest risk of launching demands a very accurate calculation and depends on natural conditions, especially tides. Some losses occurred while launching using this method. However, it was more dominant due to negligence in preparing for the launch process. This does not make the type of shipyard that uses the slip way less attractive, on the contrary, almost 75% of shipyards in Indonesia use this type before finally using the marine air bag system. Hopefully the writing above can help fellow underwriters in understanding the characteristics of launch risk in several types of shipments, especially at the closing of builder's risk.
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