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Data usage on Three Decks

This page will give you a breakdown of the data used by Three Decks and its format, definitions and any assumptions that have been made. This is not an exhaustive list, so if you find anything missing or less than helpful please let us know

Date Display

Dates on Three Decks are displayed using the format of DD.MM.YYYY (YYYY=Century+Year, MM=Month and DD=day of month). For example the 1st of February 1687 is displayed as '1.2.1687'. Where incomplete date information is available the display may be incomplete, e.g. '2.1687' means at sometime during February 1687, and '1687' means at sometime during 1687. Efforts have been made to show events with incomplete dates in chronological order, but this should not be relied on as absolutely accurate.

Julian calendar dates between 1st January and the Julian new year of 25th March, will additionally display a conversion to a Gregorian date equivalent E.g. Dates within February 1702 in the Julian calendar will be displayed as DD.MM.YYJJ/GG where JJ is the Julian year and GG the Gregorian. E.g. 1st February 1702 will be displayed as 1.2.1702/03. The Gregorian equivalent would be 12.2.1703.

All dates include a tool tip showing a text version of the date, with a Gregorian equivalent appended (indicate by the prefix NS) if appropriate. E.g. 1.2.1702/03 will have a tool tip of "1st February 1702 (NS 12th February 1703)".


There are primarily two different calendars in use within Three Decks, the Julian and the Gregorian.
Dates should be assumed to be Gregorian when from a European source, or from a British source reporting events after 1752; as a Julian date for earlier British events or for Russian events.

Conversion of calendar dates

To convert Gregorian dates to Julian and visa-versa use the table below by finding the required date and:
For a Julian to Gregorian conversion add the difference to the Julian Date
For a Gregorian to Julian conversion subtract the difference from the Gregorian date.

Some dates are now identified as a Julian date, this can be seen by hovering your mouse over the date, if the date is a Julian an additional element will show the Gregorian equivalent date in brackets, prefixed with NS

Gregorian Date Range Julian Date Range Difference
15 October 1582 to 28 February 1700 From 5 October 1582 to 18 February 1700 10 days
1 March 1700 to 28 February 1800 From 19 February 1700 to 17 February 1800 11 days
1 March 1800 to 28 February 1900 From 18 February 1800 to 16 February 1900 12 days
1 March 1900 to 28 February 2100 From 17 February 1900 to 15 February 2100 13 days

In addition here is a web link which will convert dates for you:

Adoption of Gregorian Calendars

The table below lists dates for the adoption of the Gregorian calendar together with the date of adoption of the 1st January as the first day of the year. It should be noted that many countries year started on March 25th (including England) or March 1st prior to this.

Country Adoption of Gregorian Calendar Adoption of 1 January as New Year
Venice 1582 1522
Spain 1582 1556
France 1582 1564
Dutch Republic 1582 1583
Holy Roman Empire 1583 1544
Portugal 1582 1556
Southern Netherlands 1582 1556
Prussia 1700 1559
Denmark 1700 c 1310
Scotland 1752 1600
British Empire 1752 1752
Sweden 1753 1559
Russia 1918 1700

Ship pages

Three Decks stores information about ships separately for each different period of a ships existence. This can mean that a single physical ship may actually appear several times within lists. The following are reasons why Three Decks would treat a ship as a separate vessel.

  • The ship changed ownership/operator (Sold, hired, requisitioned, captured or given away)
  • The ship was rebuilt (either nominally or actually)

However, where a ship was captured and recaptured with little time between, it will not normally be treated as a separate vessel during the intervening period.

Where a ship has several different persona, links will exists within the ship's main data to its previous and subsequent incarnations.

It was decide early on in the design of this site to exclude vessels that were ordered but never completed, and to exclude information on names that were discarded before the ship was launched. As such you will find no records of such vessels on this site. There is an intention at some point to add a simple list of ordered but incomplete vessels as well as a list of original names, but please don't hold your breath.

Ship names

Throughout Three Decks ships are given their full name without abbreviation. This is most noticeable with Spanish, Portuguese and other Catholic states where ships are always called "Nuestra Señora" or "Nossa Senhora" etc. instead of the commonly used NS. Searching for ships with names beginning NS will not work, you must use the full prefix.

Ships often had multiple names during their career, where these are an additional, alternate (including spelling variants), nickname or sacred name they are listed directly below the primary name of the ship. They may be searched for and are included in search results with the ships date of acquisition. Where a ship was renamed, this is listed as an event with the date given. New names may also be searched for but are shown with the date of the renaming, not the date of build.

French name prefixes, Le, La or Les, are not part of the ship's name and should not be included in the search.