The purpose of this study is to re-examine the effects of hydrographic factors (tides and tidal streams) and to explore the ship-hydrodynamic aspects of sailing of the fleet of William, Duke of Normandy, from St-Valéry-sur-Somme to Pevensey in the autumn of 1066.

Earlier studies involving the hydrographic factors include a paper by Laporte and a more recent and critical paper by Gillmor. As to hydrography, we shall use tidal data newly computed for us for the Somme estuary by the Hydrographic and Oceanographic Service of the French Marine for the last (Julian) days of September 1066. The main difference of our study from earlier ones is, however, in the attention paid to problems of ship hydrodynamics and our attempt at estimating the speed of winds in the English Channel during the Invasion sailing and some characteristics of the Norman ships.

The day when the wind in the Channel shifted to blow from the south (after a wait said to have been fifteen days long) and made it possible for William’s fleet to sail from St Valiéry in the Sommne estuary to Pevensey, was either 27 or 28 September (Julian dates; 3 or 4 October on the Gregorian calendar) 1066. Version ‘D’ of the ASC says that the Duke arrived at Pevensey on Michaelmas Eve (28 September), while Version ‘E’ states that he landed at Hastings on Michaelmas Day, i.e. 29 September. The nineteenth-century British historian Freeman, a scholar of the Norman Conquest, argued that the two versions are not at variance: William landed at Pevensey on the 28th, and, after disembarking troops, horses and supplies, marched to Hastings, reaching it the next day. Modern historians tend to agree that the landing took place at Pevensey on the 28th, see e.g. Douglas

Table 1 lists the source of our data:

It is appropriate to devote some attention to the weather in September 1066. According to chroniclers of the eleventh century, the first half of September 1066 was stormy in the English Channel. We have two indications for that: (i) Version ‘C’ of the ASC says that on 8 September, Harold, king of the English, disbanded the fyrd and ordered his warships to sail to London (both the fyrd and the navy were guarding Southern England) and ‘many of the ships perished before they reached London’.