Because of the tide, the Chinese ships were facing toward the shore at the start of the battle, with their cannons pointing that direction. Of course they couldn't hit the enemy ships. They became completely useless. The French ships, on the other hand, had their cannons pointed directly at the Qing vessels.
因為潮汐，開戰之時，中國兵船船首向內陸，大砲轉向自己，當然無法命中敵艦，成了不折不扣的「軟腳蝦」，反之法兵船則大砲直接對著清兵船，難怪南洋兵艦會打敗仗！