The US Voluntary Observing Ships (VOS) report surface marine observations in both real-time (FM-13 ship format) and delayed-mode (International Maritime Meteorological Tape - IMMT format). To do this, most operating vessels use e-logbook software that allows an observer to enter information, then the software can transmit a real-time report as well as save the same report in a different format to the ship's hard drive for later access, i.e. delayed mode observation (DM). Once in port, all DM reports stored on the hard drive are retrieved and sent to the National Climatic Data Center for archiving and processing. The e-logbook software used in this dataset is the TurboWin Version 5.0 program and structures data in the IMMT-4 format.