Dimitri--I think you just have bad timing, as everyone says that it is much more windy than normal right now. Friar's Bay Beach Club almost always has very calm water. You might try there. They DO NOT accept credit cards, but their food is great, classic French. Pinel is also very calm, most of the time. That would be my personal recommendation. Le Gallion beach is also very calm, with very shallow water, but absolutely NO services, so if you go, need to take whatever food and/or water that you want. Not even any chairs to rent there. ABBC is very nice, but my personal opinion (which is worth absolutely nothing, I know!! ) is that you should try a couple of other beaches. I would also suggest either Karakter or Mary's Boon, on Simpson Bay Beach.

Enjoy the rest of your trip, regardless of what you decide.