chart and publication secrets 9
If the number doesn’t fi t inside the symbol, parentheses enclose the number
next to the symbol.
Rocks that cover and uncover. Th e underlined number
gives the height above low-water datum. If no number
accompanies the symbol, uncovering information is
unknown.Smooth-edged, rounded shape with number enclosed in shape (or appear-
ing next to it in parentheses). Th ese rocks or islets are always visible. Even at
high-tide they stick out of the water, and the numbers indicate their height
above the high-water datum.
Rocks shown this way on a chart are always visible. Th e
number is the height of the rock above high-water datum.Stand-alone Rk abbreviations. Depths accompanied by the abbreviation
Rk—with or without a bracket beneath—show rocks covered by that depth at
low-water datum. Use caution when navigating close to these areas.
WRECKS
Undersea currents and surface waves and swells constantly shift many wreck
positions. Cartographers can only plot the original reported position of a
wreck. Some wreck symbols indicate danger to mariners, while others are safe
to pass over.
Th is symbol indicates rocks that are barely visible or just awash at low tide.