keel

They sense that their ship of state is no longer on an even keel.

But, as the keel of the boats touched bottom, each boat-load dashed into the water and then into the enemy's fire.

Robert was out there under the shed, reclining in the shade against the sloping keel of the overturned boat.

To maintain the vessel on an even keel he introduced four vanes, called “hydroplanes,” for regulating the depth of descent.

The tip often forms an abrupt angle with the shaft and there is a keel on the dorsal surface of the tip (see figs. 5, 6).

Microscopic examination reveals that there is a faint keel on the dorsal surface of the tip.