James Stevens weighs up the options:
They'd have a cracking sail across, a broad reach in sunshine, in a Force 4-5 – fast, and easy to ensure a legal and simple transit of the shipping lanes.
However, the passage home is very different. Although the visibility is good, a strong headwind means a long and tiring beat home. Crossing the shipping lane is legal under sail but better at right angles under power – uncomfortable and difficult against a head sea. With only two on board, fatigue is going to take its toll even with the autopilot.
There is clearly pressure to leave on such a fine day and for the social activities in Ostend, but there is a heavy price to pay on the way back. Better to stay on the English side and go on a coastal cruise on the weather shore. If it was really important to get across then the only sensible option would be to come back via ferry and leave the yacht there, which is never very satisfactory. Looking at GRIBs to get another view is a good idea but don’t fall into the trap of trawling websites until you find one that gives you the forecast you want.