Often, the source material for arrivals and departures contain different dates for the same event. This can be confusing and it is difficult to determine which date is the correct one. Even the official records held by the archive organisations have differences in the dates from one record to the next for the same vessel.

Besides an outright transcription error by a clerk, there can be significant variations in the records as to the dates of departure and arrival due to the viewpoint of the source of the information. For example, a vessel sailing into harbour at 11:00 pm will have the current day's date in the ship's log, but the harbourmaster might record the event in the next day's arrivals, especially for those vessels arriving on a Sunday.

Similarly, some papers might record the event two or three days later, when the captain and crew have landed. Other papers might record the date that the vessel sailed into the heads, dropped anchor, or cleared quarantine.

For the earlier periods, the dates from newspapers are sometimes open to interpretation. For example, the dates in the Sydney Gazette for the first two weeks of May 1804 are out by a day (it appears that they allowed 31 days for April), although the day of the week was correct. This means that there is some question as to the reported dates for vessels arriving and departing during this period.

Another issue is that many of the entries are listed by day (ie, Monday, Thursday, etc), not date. Although this was common in the early period, it still occurred occasionally in the 1840's.

The dates used in the Convictions database come from many sources. The determining factor in the date used is based on the likely accuracy of the source material. In most cases, I have relied on the dates found in the "Shipping Gazette and Sydney General Trade List", as this periodical was specifically published for the distribution of shipping information and is more likely to contain the correct information.

For ports other than Sydney, or those periods when the Shipping Gazette was not in circulation, I tend to favour the details provided by local newspapers, when they are available.

When looking for vessels in indexes using the date, the user should remember that some entries do not include a day or month. This means that the user should also check entries at the beginning of the month and the beginning of the year when looking for entries.

There is an additional problem with some coastal shipping. In the 1830's, many of the arrivals and departures for these vessels were listed with a date range, not the actual date of arrival. In these cases, the vessels are listed either at the start of the date range, or at the beginning of the month, depending on the information available.

The handwritten official records can at times be very difficult to read and interpret. This is due to both the clerk's handwriting and the fading of the ink used. Because of this, there are often several interpretations possible for the material being transcribed. Often, the correct interpretation is only possible with outside knowledge, such as knowing that a person was on a particular vessel.