What watercraft is behind the boy?
The watercraft is a ship.
    src        edge_attr  dst
0     0  to the right of   18
1     0  to the right of    9
2     3          worn on    6
3     5           behind   12
4     5   to the left of   11
5     5      floating on   10
6     5   to the left of   12
7     5      floating in   10
8     7             near   10
9     7          next to    8
10    7             near    8
11    8             near    7
12    8            below   12
13    9   to the left of    0
14    9  to the right of   18
15    9  to the right of   19
16   10           behind   12
17   10             near    7
18   11      floating in   10
19   11      floating on   10
20   11           behind   12
21   11  to the right of    5
22   11   to the left of   12
23   11   to the left of   17
24   12          wearing   16
25   12          wearing    0
26   12      in front of   10
27   12          wearing    2
28   12          wearing    1
29   12      in front of    5
30   12          wearing   13
31   12  to the right of   11
32   12  to the right of   18
33   12  to the right of   19
34   12          wearing    3
35   12          wearing    4
36   12  to the right of    5
37   12      in front of   11
38   15        on top of   10
39   15      floating on   10
40   16        on top of   17
41   17  to the right of   11
42   18  to the right of   19
43   18   to the left of    0
44   18   to the left of    9
45   18   to the left of   12
46   19   to the left of    9
47   19   to the left of   18
48   19   to the left of   12