An innovative ship salvage concept and its effect on the hull structural response

Figures & data

Figure 1. Conceptual depiction of (a) internal application of SuSy devices inflated inside the double hull of an oil-tanker vessel and (b) external application of the SuSy salvage system inflated at the starboard side of the vessel.

Figure 2. External rescue devices attached on the demonstrator (gas tanks, inflatables in their protective cases and the support frames are shown).

Figure 3. Middle section (a) and top view (b) of the double bottom demonstrator depicting the strain gauges’ positions (P and S denote port and starboard side respectively, dimensions in mm).

Figure 4. Sketch of the external frame depicting the strain gauges’ positions and measuring directions.

Figure 5. Stresses on the webs of the top plate stiffeners.

Figure 6. After 312 s, the demonstrator remained afloat at its maximum freeboard (approx. 30 cm).

Table 1. Peak and mean stress values with their 95% confidence intervals for each measuring location for the emersion phase and forward (time > 120 s) along 0° (σ_x), 90° (σ_y), 45° (σ_xy) sensor's directions and the calculated equivalent von Mises stress, σ_ν (units: MPa).

S.G.	σx	σy	σxy	σν
A1	20.75 ± 1.12	10.91 ± 0.42	4.28 ± 0.20	21.42 ± 0.93
(peak)	(53.51)	(23.72)	(10.17)	(49.67)
A2	4.30 ± 0.19	-10.37 ± 0.89	-0.95 ± 0.13	16.70 ± 0.74
(peak)	(13.02)	(-44.61)	(-7.31)	(43.52)
A3	6.81 ± 0.10	3.09 ± 0.09	1.30 ± 0.02	6.73 ± 0.09
(peak)	(11.85)	(5.22)	(2.27)	(11.39)
A4	5.29 ± 0.06	4.77 ± 0.04	1.36 ± 0.02	5.65 ± 0.05
(peak)	(7.31)	(6.67)	(2.41)	(7.57)
B1^a	–	–	–	–
B2	−3.51 ± 0.36	−19.73 ± 0.67	−2.64 ± 0.12	19.90 ± 0.56
(peak)	(−14.86)	(−39.89)	(−6.29)	(36.64)
C1	13.05 ± 0.34	13.19 ± 0.38	3.31 ± 0.09	14.35 ± 0.39
(peak)	(22.38)	(25.16)	(5.70)	(25.85)
C2	17.31 ± 0.26	16.93 ± 0.24	5.12 ± 0.09	19.31 ± 0.29
(peak)	(29.40)	(25.74)	(9.14)	(31.95)

^aFailed to record strains in any direction.

Figure 7. (a) Emersion of the partially inflated spherical inflatables at approx. 7 s (phase i); (b) beginning of the demonstrator's emersion at approx. 50 s (phase ii); (c) end of the demonstrator's emersion at approx. 120 s (phase iii).

Figure 8. Stresses at the frame (sensors C3, C4) and at its attachment to the demonstrator (sensor C5).

Table 2. Peak and mean stress values with their 95% confidence intervals for each measuring location for 0 s <time<120 s, along 0° (σ_x), 90° (σ_y), 45° (σ_xy) sensor's directions and the calculated equivalent von Mises stress, σ_ν (units: MPa).

S.G.	σx	σy	σxy	σν
A1	−0.63 ± 0.04	0.02 ± 0.04	−0.07 ± 0.005	0.76 ± 0.03
(peak)	(−1.92)	(−1.34)	(−0.29)	(1.78)
A2	−0.77 ± 0.03	0.2 ± 0.03	−0.03 ± 0.005	0.94 ± 0.03
(peak)	(−2.09)	(1.07)	(−0.22)	(1.90)
A3	−0.28 ± 0.15	−0.17 ± 0.12	−0.13 ± 0.04	1.65 ± 0.09
(peak)	(3.41)	(3.11)	(−1.02)	(3.61)
A4	0.65 ± 0.07	0.61 ± 0.07	0.12 ± 0.01	0.82 ± 0.06
(peak)	(2.24)	(2.38)	(0.44)	(2.43)
B1^a	–	–	–	–
B2	−0.95 ± 0.04	−0.27 ± 0.02	−0.18 ± 0.01	0.95 ± 0.04
(peak)	(−2.00)	(−0.98)	(−0.44)	(1.90)
C1^a	–	–	–	–
C2	2.00 ± 0.08	0.99 ± 0.07	0.40 ± 0.02	1.94 ± 0.07
(peak)	(3.36)	(2.49)	(0.73)	(3.24)
C3	−27.03 ± 0.80	–	–	–
(peak)	(−38.41)
C4	16.32 ± 0.76	–	–	–
(peak)	(34.04)
C5	47.18 ± 1.46	36.95 ± 1.12	–	–
(peak)	(63.84)	(49.71)

^aFailed to record strains in any direction.

Figure 9. Response of the frame under maximum buoyancy load in terms of von Mises stress (in MPa).

Table 3. Mean stress values with their 95% confidence intervals at locations C3 and C4 for 120 s ≤ time ≤ 180 s.

S.G.	Tests (MPa)	Finite element analysis (MPa)	Relative difference (–)
C3	−31.6 ± 0.1	−30.8	3%
C4	12.3 ± 0.1	13.8	12%