Battle of Hastings - The Departure from Dives
Some Fundamentals
1. The ships that William used were in some way related to the ships of the Vikings. This means that the ships -
a) had shallow draft,
b) had removeable benches for the rowers,
c) carrying horses these benches were removed,
d) carrying horses the only means of propulsion was the wind.
e) carrying materiel had two means of propulsion ( oar and/or sail) or not.
f) could sail up to 12 points off the wind (so if the wind was a straight northerly, the ships could point at 13 degrees and still make forward progress).
2. Over the years, I believe, the Normans had lost some of the seafaring ability of their forefathers.
What the sources say - if anything
Will of Poitiers says that they waited for a southerly wind. After a while this turned into a westerly wind which blew them to St Valery sur Somme.
Will of Jumièges doesn't acknowledge leaving Dives only assembling at St Valery sur Somme.
The Carmen is a bit more expansive but equally opaque. it reckons that the way was barred by constant rain and storms and thus the fleet sheltered at St Valery sur Somme. More bad weather was experienced and there was a pulse of warmth just before Michaelmas at which point the fleet made ready to depart for England.
Deductions?
I think the initial delay at Dives was caused by onshore breezes rather than actual Northerlies. So a typical day might consist of a warm sunny day in which the wind in the morning was slack but by afternoon was streaming from the north as Dives was a north facing port. As the ships carrying horses had no means of propulsion other than wind the Normans were stymied and had to wait for a proper wind to propel them out of the River Dives.
A consequence of waiting for a southerly would be the arrival of a storm shortly afterward. This would mean that the wind would veer into the westerly half of the compass as the Low pressure system centre passed to the north of the fleet. The coast of France in this area turns from north between Dives and Fecamp to south west to north east between Fecamp and St Valery sur Somme.
The upshot of a strong westerly wind would be to drive the fleet into various harbours and ports along the coast between Fecamp and St Valery. So, in my opinion, the three weeks being "stuck" in St Valery would have been used to re-assemble the fleet at St Valery before continuing to England. I would imagine that there would not be excessive loss of life and the claim made by Nick Austin that the Normans lost a ship carrying a "flat pack" fort to England ( two flat pack forts instead of three) hard to understand.
