Running

bufrextract.pl sn.0113.bin --ahl "^IOB" --outfile iob.dat

will extract all BUFR BUOY messages from the file sn.0113.bin of GTS bulletins into iob.dat, whose content can be checked with bufrread.pl, see excerpt here.

Adding --without_ahl in the command above will lead to the obvious change of not including the AHLs in iob.dat