The Allied Air Forces adopted some innovative tactics. In February 1942, the RAAF began experimenting with skip bombing, an anti-shipping technique used by the British and Germans. Flying only a few dozen feet above the sea toward their targets, bombers would release their bombs which would then, ideally, ricochet across the surface of the water and explode at the side of the target ship, under it, or just over it. A similar technique was mast-height bombing, in which bombers would approach the target at low altitude, , at about , and then drop down to mast height, at about from the target. They would release their bombs at around , aiming directly at the side of the ship. The Battle of the Bismarck Sea would demonstrate that this was the more successful of the two tactics. The two techniques were not mutually exclusive: a bomber could drop two bombs, skipping the first and launching the second at mast height. In addition, as regular bomb fuses were designed to detonate immediately on impact, which would catch the attacking aircraft in its own bomb blast at low altitude attacks, crews developed a delayed-action fuse. Practice missions were carried out against the wreck of the , a liner that had run aground in 1923.