After checking the forecast it would make sense to have the wind on our backs over the dijk. So, as Paula suggested, we should ride the opposite way around. The new details are listed below...
Meet at Centraal Station ferry point @ 08:00 (NEW TIME!!)
Ride to Stavoren - 140km (we have plenty extra time to stop on the dijk and grab a bite to eat afterwards)
Catch the 14:25 ferry back to Enkhuizen (price 10.60 for you & 5.20 for your bike)
Just in case they don't accept cards, have cash on you for coffee on the ferry.
Arrive in Enkhuizen @ 15:45 and take the train back to Amsterdam
Overcast, winds from the South West at 4Bft. High of 17'c
(More details about Afsluitdijk - http://en.wikipedia.org/wiki/Afsluitdijk )