Complex sentence: Hitler said that the break-out should be planned with no training period, since British intelligence was bound to find out and have the ships bombed and a period of bad weather should be chosen, when the bulk of the RAF was grounded.
Split into simpler sentences: Hitler said that the break-out should be planned with no training period, since British intelligence was bound to find out and have the ships bombed. He also ordered that a period of bad weather should be chosen, when the bulk of the RAF was grounded.