  Sailing robots provide a low-cost solution to conduct the ocean missions such
as marine exploration, pollution detection, and border surveillance, etc.
However, compared with other propeller-driven surface vessels, sailboat suffers
in complex marine wind field due to its low mobility. Especially in tacking,
sailboats are required to head upwind, and need to make a zig-zag path. In this
trajectory, a series of turnings, which will cross the challenging no-go zone,
place significant challenge as it will reduce speed greatly and consequently
result in unsuccessful turning. This paper presents a hybrid sailboat design to
solve this issue. Electric propellers and control system are added to a model
sailboat. We have further designed the control strategy and tuned the
parameters (PWM-time) experimentally. Finally, the system and control can
complete the tacking maneuver with average speed approximately 10% higher and
enhanced success rate, though the sailboat weight is much heavier.
