centreboard
/ˈsɛntərˌbɔrd/
noun
- A movable board or keel that can be lowered through the bottom of a sailboat to prevent it from drifting sideways.
- The sailor lowered the centreboard to keep the boat stable in the strong wind.
- Before racing, the crew checked that the centreboard moved smoothly in its slot.
- A small dinghy often uses a centreboard instead of a fixed keel.