Top Ten Concerns for Ship Launching using Marine Rubber Airbags

Ship launching using marine rubber airbags is a very popular launching method, particularly in Asia. Besides, many shipyards choose airbags for ship repairing and maintenance. The use of such marine rubber airbags may seem to be quite simple and straightforward, yet there are still some important principles that need to be followed strictly to ensure the success of launching work.

No. 1 Identifying the main dimensions of the vessel to be launched

Many factors like types, sizes, weight, working height (distance between the hull of the ship and ground) of the vessel will affect your choice of airbags. The main structure of the vessel is a vital parameter in determining the placement of the rubber airbags.

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No. 2 Choosing the right type, length and number of marine rubber airbags

There are many types of airbags. They are different in number of rubber layers, rubber quality, strength of the layers etc. The dimensions of rubber airbags in terms of diameter, length and layers determine its lifting/bearing capacity.

No.3 General ground structure preparation

First and foremost, a hard ground is a must to have a safe and successful launching.  The suitability of the launching area must be considered and steps taken to prepare it. Although some launch their vessels on soft ground, it is not worth the risk and is not advisable.

No.4 Slipway has to be free of sharp objects, a small degree slope will be better

Additionally, the launch way must be free of hard and sharp objects like sharp metal plates, big stones etc. These may damage the rubber bags during launching work.

No.5 A slipway winch is needed

A slipway winch is needed to hold the vessel in place (prevent it from slipping into the water) during the placement of airbags. Slope angle, weight and type of ships should be carefully considered to determine the winch capacity. A choice of electric winch or hydraulic winch also depends on the facilities of the shipyard and the aspects of its usage.

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No. 6 Determine the accessories needed for ship launching using marine airbags

Accessories like pulley blocks, shackles, steel wire rope etc. may be needed. The types of accessories and volume depends on the situation.

No.7 Determine whether a slow launch or quick launch

Some launchings are done by releasing a quick release shackle (the connection between the winch & the vessel) and the vessel is allowed to slide into the water facilitated by gravity. However, for trickier situations, a slow launch where the winch slowly releases the rope and the vessel is allowed to slide slowly may also be practiced. For slow launches, the balance of the ship is ensured so if at any point of time it falls out of balance, the winch will be immediately stopped and corrections can be made.

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No.8 Placing of Rubber Airbags

For the light weight vessel, only several pieces airbags can fully lift the vessel at one time and then remove the blocks and place more airbags for launching.

For the big weight vessel, it should be lifted step by step. First put the airbags under the vessel. Second pump part airbags. Third adjust inflated airbags’ position to be accurate since during lifting some airbags’ positions are hampered by blocks. Fourth pump more airbags to continue release blocks and remove them. Fifth repeat pumping and remove until all blocks are removed.

No.9 Marine Rubber Fenders are versatile

Aside from ship launchings and used to facilitate pulling vessels out of the water, these rubber airbags can be also used to mobilize heavy structures like caissons, floating jetties and other equipment. Moreover, it is very commonly used in marine salvage projects where it is used to float or lift. Many shipyards are pleased that aside from using these rubber airbags for their ships, they are able to use them for other purposes as well. This versatility has served them well.

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No.10 Cost effective due to flexibility

Ship launching using rubber airbags have relatively lower costs, especially upfront investment. The most interesting aspect is its “scalability”. Many ship repair yards in Asia prefer this method as they can increase their ship repair capacity whenever they want and not be restricted by say, the dimensions of the dry docks they own.