Early maps and sea charts offer a great deal of insight into the past. Prior to the 16th century, mapped depictions of Ireland were part of the culture of other nations. From the 16th century onwards, maps and charts became increasingly more technically sophisticated and accurate with regards to placenames and topography. By the 17th century, the emphasis in mapping had shifted from maps for defence and military campaigns to the plotting of large areas as part of the process of confiscation of land. In addition to maps, a diverse range of charts of Ireland were created from the 16th century onwards. Charts created for defensive purposes often included large scale mapping of ports and anchorages. A comprehensive list of early maps and charts of the Irish coast is provided in Exploring the Maritime Archaeology of Ireland.
Cartographic and topographical records of the Irish coast are a major source of useful archaeological, architectural and topographical information, and there is extensive literature on Irish map history (Andrews 1962, 1997; Hayes 1965, Ferguson 1985, Walls 1994). A wide range of these historic maps depict maritime features in varying levels of detail (Robinson 1962, Chriss & Hayes 1964, Wallis 1994, Whitfield 1996). Copies of the most important maps are available at the Map Library, Trinity College Library, the National Library of Ireland, the National Archives of Ireland, the British Library and the National Archives of the United Kingdom (see respective entries below). A guide to selected map archives was produced by Prunty (2004), and useful catalogues of maps are provided by Andrews (1993) and Ferguson [undated] held in the Map Library of Trinity College Library. Maps held in the National Library of Ireland can also be found through the online library catalogue.
Sea charts are maps made for the use of seamen, and while primarily intended for the purposes of navigation and safe voyaging, these charts are of great relevance to maritime archaeological studies as they show the areas of land mariners were most interested in – ports and landing places, key headlands and navigational dangers to be avoided. In the 16th century, charts were commissioned for defensive purposes, resulting in the charting of ports and anchorages (Robinson 1962, Terrell & Wallis 1994) including the large collection of Tudor-period manuscript charts collected by Sir Robert Cotton (the Cotton manuscript collection held in the British Library). In 1681, the Admiralty and Trinity House commissioned a naval officer, Greenvile Collins to survey the harbours and stretches of the coasts, which included Ireland. Official surveys by Murdoch MacKensie senior (1712-1797) included surveys of the whole of the coast of Ireland, published in 1776 in London as A Maritime Survey of Ireland and the West of Great Britain.
In addition to maps and charts, mariners notebooks and pilot books can also be useful. Before sea charts became widely available, mariners made notes of courses to and from ports, capes, the distances between points of recognition, the flow of tidal streams and coastal currents, the time of high water and soundings (Waters 1958). These notes were compiled into a notebook, which may include sketches of capes and headlands and harbour entrances. With the advent of printing, manuscripts were made more widely available as ships’ rutters. The first known to be printed was in French Le Routier de la Mer, and anglicised as The Rutter of the Sea (Douglas 2003).
A detailed discussion about early charts and a comprehensive list of pre-1900 maps and charts of the Irish coast is provided in Exploring the Maritime Archaeology of Ireland.