Introduction:
Marine rubber airbags are also know as marine airbags and ship launching airbags. It's made by synthetic-tire-cord reinforcement layers and natural rubber layers.
Marine Rubber Airbag is China independent intellectual property rights of innovative products, the products are mainly applied to ship launching and landing, weight lifting, handling, installation of underwater buoyancy aid etc. Nowadays, marine rubber airbags are widely used in the world. The Products are less limited by space, no large mechanical equipment, can shorten the working period and save the unnecessary cost. Through years of development practice, marine rubber airbag is become more safety, effective and green environmental protection.
Comparing to the traditional slipway docking and launching method, the marine rubber airbags are much environmental, It's low cost and low risk. Unlike most other launching methods that are fixed infrastructures, ship docking airbag has relatively less limitations and can be used in versatile ways. It overcomes the disadvantage of fixed track docking in which capacity of shipbuilding and ship repairing is limited by the fixed infrastructures especially in small and medium-sized shipyards. Marine rubber airbag can dock a ship at any seaside.
Besides, the marine rubber airbags need little maintenance and can be used repeatedly.
The marine rubber airbags provide support to the hull of the ship, its rolling motion take a vessel out of the water or launch into water. Thus it is obviously more safety than other options like sideways launching.
Application:
Airbag is more and more widely applied in ship launching project. The application method is ceaselessly improved. The airbag
application application method for common medium ship launching ship launching is as below,
1. Based on calculation result, enough rolling airbags and lifting airbags, towing machines and air compressors are prepared.
Before using, airbags must be inflated and tested without loading(the testing pressure must be no less than 1.25MPa). In case of
air leakage, the airbag must be prepared before using.
2. The way for ship movement, including the way from shipbuilding berth to ramp, must be cleaned and flattened. Sundries must be
removed from the way, especially sharp iron nails and stones, to avoid piercing the airbag. The ramp should be long enough and
wide in water.
3. All the protruding sharp corners and burrs on casting like ”A” bracket and stern post must be polished to be smooth.
4. Fasten the hull with the steel cable of winch.
5. Close the sea chest valves of ship, fix the rudder and propeller.
6. There are many ways to remove all blocks and fill in the rolling airbags. Here we recommend two methods as below. User may
choose one basing on the equipment conditions such as ship weight, amount of the airbags, etc.
(A)For light ship, the bearing capacity of the airbag is large enough to lift the ship away form the blocks and therefore blocks
can be removed directly and fill in the airbags.
(B)For heavy ship, lifting airbags can be adopted to lift the bottom of stern. Before lifting, firstly specify the optimum
position of the front-pivot and lifting airbags. According to the figure as below,
the closer the front pivot to the center of gravity the better, however, it will result in too many blocks around of the
front-pivot, which means a lot of workload to remove the blocks manually. Therefore, the position shall be determined reasonably
considering such elements as ship length, etc. If possible, the lifting airbags shall be located in the stern. However, the
location is also subject to line shape of the stern as the lift of the lifting airbag will not be enough if the bottom is too high
to the ground. In this condition, it would be better move forward. Therefore, the optimum position of the front-pivot and lifting
airbags shall be decided after specific calculations as the case varies from ship to ship.
Q*Lq＞W*Lw
In the formula,
Q=lift of the lifting airbag
W=weight of ship
Lq= the distance from the lift center of the lifting airbag to the front-pivot
Lw=the distance from the center of gravity of the ship to the front-pivot
7. Firstly, remove all the blocks in the lifting airbags and the ones around the front-pivot. Then fill the lifting airbags and
start inflating until the bottom separates slightly from the blocks. Remove blocks one by one from middle to the stern. Whenever
blocks of the section are removed, fill in the rolling airbags immediately in the planned position and inflate it appropriately.
Followed by continuous block removing until all blocks in the stern are completely removed and the rolling airbags are filled in.
8. Remove blocks from the middle of the ship to the front-pivot and fill in all rolling airbags in the front by modifying pressure
of the airbags filled in the stern or similar methods as mentioned above. Of sake of safety, add removed blocks in appropriate
number between the filled rolling airbags at any time. The blocks will not be removed until the rolling airbags can support the
weight of the ship. Besides, when removed blocks of the same section, it shall be started from middle to both sides. When remove
the outermost block, workers shall carry out the work outside the fender.
9. Adjust pressure in the airbags so that the bottom can be lowered to appropriate working height. Make sure that the bottom will
not touch the ground while moving the ship. For average small-size ship, the working height could be chosen within the arrange of
0.2m-0.3m.
10. All airbags shall be pointed at the center of the ship and perpendicular to the launching direction.
11. Start the traction winch to release steel cable slowly followed by slow movement of the ship. When the forefront airbags
located in the front part separates from the bottom, it shall be placed under the stern immediately and fill in the airbags
according to the arrangement space of the airbags defined in the calculations.
12. Repeat the above process to move the ship to waterside slowly. When the airbags can’t be filled in, block the river and forbid
any ships to pass.
13. Evacuate personnel in the dangerous zone, Inform staff on the ship to get ready. When conditions such as water depth and so on
are enough, cut cable or unhook to shat the ship can launch quickly. If the river is too narrow to realize quick launching,
release the cable slowly by traction winch to launch the ship slowly.
14. For large ships, it is necessary to install anti-slip device.
15. Collect the airbags.
