• Q. Is this the first type of sail in the world?
  • A. Our totally-enclosed, rigid and telescopic sail is the first challenge in the world. We have already patented in Japan, USA, and Europe.
  • Q. There were some sailing cargo ships in Japan. Whatfs different from these sailing ships?
  • A. In 1980s, Japan Marine Machinery Development Association (JAMDA) developed the rigid sail with camber (JAMDA sail) and loaded two of the sails on a domestic tanker name Shin-Aitokumaru. However, with a small sail and the concept of gEngine main, Sail assisth, JAMDA project could only save 10 % of fuel usage at most. On the other hand, with the concept of gSail main, Engine assisth, we can expect more significant energy reduction from Wind Challenger.
  • Q. How about the effect of energy saving?
  • A. The Height and width of actual sail that we are developing now are 50 m and 20 m respectively. When 4 of these sail are installed into a 84,000tons deadweight capacity bulk carrier, we estimate that more than 30 % of yearly average energy saving is possible for the round voyage between Yokohama, Japan and Seattle, USA. This result is based on the optimum routing simulation. Furthermore, this ship can reduce over 50 % of fuel usage if you are always in the side windEtail wind condition.
  • Q. What wind speed and direction are efficient for this sail?
  • A. The sail can produce more force with the stronger wind speed, and the side wind is the most desirable wind direction for sailing cargo ship. Head wind is useless while tail wind is inefficient for the voyage. Considering the strength margin of the sail, we can produce the sail force most efficiently at about 15 m/s of side wind, which is almost the same as the full throttle of engine.
  • Q. Is a massive reinforcement for shipfs hull needed?
  • A. As only the similar deck reinforcements when a cargo ship is installing a general deck crane on its deck are required, cargo space can be maintained.
  • Q. How about the engine of this sailing ship, compared with existing ships?
  • A. We are going to use the most energy-efficient diesel engine that is being used by the existing ships right now. However, as wind power is usable, it enables us to choose for a smaller power engine.
  • Q. How much will it additionally cost in an actual sailing cargo ship?
  • A. Suppose the cost of a full-scale sail is about 200 million yen (around 2 million dollars). Therefore, the total costs of 4 sails and the construction fee of moving the bridge to the bow for a better visibility would be 900 million yen (around 9 million dollars).
  • Q. Can these costs be recovered?
  • A. Suppose that we equip 4 sails on a 84,000tons deadweight capacity bulk carrier, which spends 32 tons of fuel per day (650 dollars per ton) on a voyage. Letfs say this sail ship navigates 220 days per year and with 36 % of energy saving on average, the annual gain of saving fuel usage amounts 1.64 million dollars. This means that you can recoup the initial investment of 9 million dollars in about 5.5 years.
  • Q. When will we complete the first ship?
  • A. Right now we are in the stage of on-land testing in Sasebo, Nagasaki (until September 2014) to ensure the function, performance and strength of the sail meet our standard. After that, we will seek for a ship owner and we are planning to have the first ship to be in service at 2016.

Questions for on-land test

  • Q. What are the material and the thickness of the test sail?
  • A. Sail was made of sandwich structure with GFRP (Glass Fiber Reinforced Plastic) and PET foamed core. The thickness of the sail is 60 mm.
  • Q. What are you measuring in on-land test?
  • A. We measure the displacement and stress at the bottom of the mast in various wind speed and direction. From that, we estimate the operating force created by the sail. We also ensure that the rotating and elastic speed are same as we planned.
  • Q. How strong wind can this sail be tolerable?
  • A. The bottom of the mast of this sail can withstand average wind speed of 20 m/s, and maximum instantaneous wind speed of 30 m/s. In the case of higher wind speed, this sail can reduce the wind force by shrinking the sail which makes sail area and mast friction smaller.