OUTPUT ESTIMATION IN OPEN SEA 　 True line in Figure 13 shows air output by 10 cm constant Wave. It is 6.9 watts in peak at 1.25 sec, and drops sharply in short and long periods. For models of single BBDB 1,183 mm long and 510 mm wide dotted line shows air output by H/L=1/40 which is average wave in open sea, and is 2.2 watts in average wave. Scale up ratio to open sea from this model is estimated 36 times for the West coast of Ireland. Buoy is 42.6 m long and 18.36 m wide. Air output increases to 36 to the power of 3.5(36=279,936) which is equal to 2.2 watts x 279,936 = 616 KW. 　 Figure 13. Air output by 10 cm constant wave, and by H/L constant (1/40) wave 　 When prototype BBDB is scale up 25 times for low wave power area such as near Japan and Hawaii. Buoy is 29.6 m long, 12.75 m wide, and 2.2 watt x 78,125=172 KW. 　 MOORING FORCE OF BBDB and TERMINATOR BBDB 　 Mooring force of BBDB is influenced by direction of duct. Figure 14 shows mooring force difference by direction of Duct for single float BBDB with cylinder duct (2.4 m long, 0.6 m wide) by 5 cm wave. Mooring force was 0.3 Kg in backward bent duct condition, and 1.2 Kg in frontward bent duct condition. Backward can decrease mooring force from 1.2 Kg to 0.3 Kg. This is a function of bending duct, oscillating water in side of the duct. Produces frontward force by changing the water direction at the bent duct. Mooring force of terminator was measured by wave height 0.1 meter for float number N as shown in Figure 15 is not proportional to N. It is proportional to the root of N. 　 Figure 14. Mooring force of BBDB by direction 　 Figure 15. Mooring force of Terminator BBDB by float numbers 　 TURBINE AND VALVE BOX 　 Impulse turbine with valve was used in Kaimei. It is consisted of guide vane and rotor as shown in Figure 16. Eight turbines were used in Kaimei test. It operated safely for more than seven years. The turbines were 1.4 m in diameter. Constructed of anti-corrosion aluminum. They had relatively good performance operating at over 60% efficiency. 　 Wells turbine was used for this test, but efficiency in high wave conditions was not efficient and noise problems have not yet improved. Airflow by wave is oscillates, a check valve mechanism is necessary to use this impulse turbine. Two check valve box (three turbine unit) was used in Kaimei from the first year test. Four check valve box (three turbine unit) was used the following year, in the second test. 　 Figure 16. Impulse turbine 　 Figure 18. Two valve system with turbine 　 Figure 17. Valve boxes 　 Figure 19. An example of generation by 4 m wave on KAIMEI (2-Valve) 　 Two-valve box consisted of two air chambers and two check valves. When wave height Hs is 4m. Air pressure was 0.5 m Aq on the plus side and 0.8 m Aq〜0.6 Aq on the minus side as shown in Figure 19. Since Hs=4 m, specific air pressure ratio was 0.13 in plus side, and 0.22〜0.15 in minus side, and generated electric power was 40-150kw as shown in Figure 19 (Kaimei generation data). It has minute order output variation by Sea wave characteristic. 　 Figure 20. Example of design of Valve (Flat valve and butterfly valve) 　 Comparing 2-valve box and 4-valve box, output was almost the same. However the 2-valve box had advantage over the 4-valve system. The number of turbines is half of the 4-valve system. The design shown in Figure 20 may be adopted to keep valve safety by throttling the flow of air. Therefore slowing down of the valve turning speed and balancing the two way turning force. 　 Wells turbine was used to study the elimination of valves. It is very simple. It rotates in the same direction with bi-directional flow of air. But conversion efficiency was low, particularly; efficiency drops in high wave condition by stall characteristic of symmetrical blade turbine. Therefore it will be difficult to use it. Another candidate turbine is Setoguchi turbine developed by Saga University and Limerick University. It has rotor with crescent shaped and two guide vanes in both sides as shown in Figure 21. Recently this turbine was studied by Limerick University. Max efficiency of 46% was obtained. It was lower than impulse turbine. 　 Figure 21. Setoguchi Turbine