 Another reported problem with the Type <unk> Is was the tendency to break trim after the firing of torpedoes . The boats were equipped with <unk> tanks designed to flood and offset the loss of the C / 06 torpedo 's 1 @,@ 700 @-@ pound ( 770 kg ) weight , but this system did not always function properly ; as a result , when firing from <unk> depth the boat could <unk> after firing or , if too much weight was taken on , <unk> to the depths . When <unk> @-@ 15 torpedoed and sank Italian submarine <unk> in June 1915 , the tank failed to properly compensate , forcing the entire crew to run to the stern to offset the trim imbalance . 
