During the planning stages of Sea Lion, it was deemed desirable to provide the advanced infantry detachments (making the initial landings) with greater protection from small-arms and light artillery fire by lining the sides of a powered Type A barge with concrete. Wooden slides were also installed along the barge's hull to accommodate ten assault boats ("Sturmboote"), each capable of carrying six infantrymen and powered by a 30 hp outboard motor. The extra weight of this additional armour and equipment reduced the barge's load capacity to 40 tons. By mid-August, 18 of these craft, designated Type AS, had been converted, and another five were ordered on 30 September.