The distance from the still water level (corrected for tides and storm surge) to the bottom of the hull of a ship is the（）.

Due to lapse of time the risk in these areas to surface navigation is now considered （）than the ordinary risks of navigation，but a very real risk still exists with regard to anchoring，fishing or any form of submarine or seabed activity.

The Earth has the shape of a(n) （）.

As these features are not all charted，special caution should be exercised （） vessels navigating in the vicinity.

The distance between any two meridians measured along a parallel of latitude and expressed in miles is the （）.

On a voyage from Halifax,N.S.,to Dakar,West Africa,the Canary Current will （）.

Lateral movement of the vessel to leeward of its course defines （）.

Attention is called to the fact that in many cases charted depths may be decreased by up to （）.

AFTER DROPPING THE PILOT means （）.

The distance between the surface of the water and the tidal datum is the （）.