Nippon Steel

The development of the large cage system drew on Nippon Steel Engineering’s experience in technology for offshore structures such as oil and natural gas platforms. Unlike structures that are fixed to the seafloor, however, cages floating on the sea surface must be able to withstand wave and current force. Furthermore, because Japan experiences frequent natural events such as typhoons, cages need to be able to submerge below the surface of the sea in order to withstand winds and waves that are more severe than in inshore waters. To assess the effects of waves and water currents, numerous simulations were conducted to analyze a wide variety of parameters using scale models and computational techniques. The results indicated that performance would be adequate for open water environments, including that the required strength could be achieved along with reliable raising and lowering of submersible cages despite their size, approximately 50 times larger than those used currently. This technology could possibly provide a pathway to higher fish production.