The university has created a new type of electric boat "RAICHO-S" in 2011. The craft has some special and unique features that set it apart from existing electric boats or battery-powered boats. "RAICHO-S" utilizes a lithium-ion battery with plug-in system or a rapid charging system. A dockside-mounted rapid charger can bring the boat's battery up to 80% of full charge within 30 minutes, which is a much shorter time than is possible under conventional charging systems. The boat can operate for 45 minutes and berth for 30 minutes in a cyclic operation. The powerful lithium-ion battery gives the boat a running speed capability of around 10 knots, enabling it to navigate not only in flat-surface waters but also in open sea conditions where wind and waves prevent operation by conventional battery-powered craft. "RAICHO-S" utilizes a water jet propulsion system driven by electric motor whose advantages are safety for the diver, passing floating rope on fish preserve, environmental reservation (no-damage on leafs, fishes, and aquatic plants) and causing no cavitation. The disadvantage of water jet driven by combustion engine in low efficiency and low maneuverability at low speed can be overcome by use of electric motor. In addition, "RAICHO-S" has a waterproof wired remote control system with a control knob that can be moved through 360 degrees to steer the boat in any direction. Its special features and advantages such as low noise, low vibration, high environmental advantages, highly-safe and highly-functional operation are expected to be useful in a wide range of areas which require underwater works.

- Outline of "RAICHO-S" -
8.04 m
2.24 m
0.85 m
1.3 ton
Motor output
40 kW
(Half load)
10 knots
(Full load)
8.5 knots
Navigation service
(10 knots)
45 minutes
(6 knots)
2.5 hours
Battery capacity
23 kWh

- Control system of "RAICHO-S" -
control system
- Water jet propulsion system -
water jet photo1
Design drawing of water jet Water jet propulsion system (reverser and deflector)
photo2 photo3
Water jet propulsion system (motor and intake)