A couple of people have recommended adding fleetcode, suggesting bulletins such as those at

http://ftp.hb-yacht.ch/ASXX21.060600 . At this point I am unable to implement Fleetcode.

Here is the problem (you may refer to

WMO Pub 306 (1.7 MB, PDF):

(1) The header is 33300, which indicates a FM 45-IV IAC code (non-abbreviated fleetcode). Therefore positions are expressed as "yyyyy", which is defined by "333x1x1" in the header.

(2) WMO provides an ambiguous scheme for finding longitude in this scheme. In our data sample, "x1x1" is 00, which means yy is LaLaLoLoK. Note that this gives only two digits with which to express longitude. In fact, LoLo specifies that the hundreds digit is deleted.

Therefore, if we get a value of "35" for LoLo, this could be either 35 or 135 degrees. If K=5, then according to K (Table 2200) we could have either 35W or 135E. This is not a sensible answer, and is unplottable.

Unfortunately I have no choice but to cease work on Fleetcode unless someone can point out a solution I may have overlooked.

Tim