# Calculation for high and dry docking system using airbag

Given the condition and dimensions as below:

1) Length of ship: 33m
2) Weight of ship: 160 tonnes
3) Using only excavator to tow the ship up.
4) For high and dry docking
5) D=1.8m (5.90ft)
6) Working pressure=0.11MPa (15.95 psi)
7) Working height= 0.9m(2.952 ft)
8) Guaranteed bearing capacity per unit length = 155.59kN/m

What is the number of airbag needed? And any more information needed for calculating this situation? Thanks.

You may send me an email. We can supply a detaild soluation for you about the air bags required for the ship launching.
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Type No.
Diameter
Effective Length
Overall Length
Safety working pressure
Operating height
Bearing capacity per meter
Bearing capacity per piece of airbag

S21
m
m
m
MPa

m
kN/m
Ton/m
kN
Ton

1.8
20
23.1
0.11
0.3D
0.54
213.2
21.76
4265.0
435.2

0.4D
0.72
182.8
18.65
3655.7
373.0

0.5D
0.90
152.3
15.54
3046.4
310.9

0.6D
1.08
121.9
12.43
2437.1
248.7

0.7D
1.26
91.4
9.33
1827.9
186.5

0.8D
1.44
60.9
6.22
1218.6
124.3

160 tons shows it is a very small ship. Our Nanhai Airbag can lift it up with 1 piece of airbag (7 layers 1.8mx20m 3 nylon thread cords) . the distance between the airbags
should be 5-6 meters ,so under the ship we need 5 pieces ,plus 2 pieces spares airbags. we need 7-8 pieces for your ship .