Bellhop: my ray tracing seems to be off - what could be wrong?

The env file used:

'Test Scapa Summer' ! TITLE

10.0 ! FREQ (Hz)

1 ! NMEDIA

'SVN' ! SSPOPT (analytic or C-linear interpolation)

51 0.0 260.0 ! DEPTH of bottom (m)

0.0 1498.18 /

10.0 1498.34 /

20.0 1498.51 /

30.0 1498.67 /

40.0 1498.83 /

50.0 1499.00 /

60.0 1499.16 /

70.0 1499.32 /

80.0 1499.49 /

90.0 1499.65 /

100.0 1499.81 /

110.0 1499.98 /

120.0 1500.14 /

130.0 1500.30 /

140.0 1500.47 /

150.0 1500.63 /

160.0 1500.80 /

170.0 1500.96 /

180.0 1501.12 /

190.0 1501.29 /

200.0 1501.45 /

210.0 1501.62 /

220.0 1501.78 /

230.0 1501.94 /

240.0 1502.11 /

250.0 1502.27 /

260.0 1502.43 /

'A' 0.0

260.0 1600.00 0.0 1.0 /

1 ! NSD

15.0 / ! SD(1:NSD) (m)

51 ! NRD

0.0 220.0 / ! RD(1:NRD) (m)

1001 ! NR

0.0 80.0 / ! R(1:NR ) (km)

'R' ! 'R/C/I/S'

0 ! NBeams

-20.0 20.0 / ! ALPHA1,2 (degrees)

0.0 250.0 85.0 ! STEP (m), ZBOX (m), RBOX (km)