242 sec? (not counting any time on shore)
A,B cross, A returns, 3 sec
C,D cross, B returns, 6 sec
A,B cross, A returns, 3 sec
E,F cross, B returns, 8 sec
A,B cross, A returns, 3 sec
G,H cross, B returns, 10 sec
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W,X cross, B returns, 26 sec
A,B cross, A returns, 3 sec
Y,Z cross, B returns, 28 sec
A,B cross................, 2 sec
Total time = 242 sec