What are sea charts called?

What are sea charts called?

nautical chart
A nautical chart is one of the most fundamental tools available to the mariner. It is a map that depicts the configuration of the shoreline and seafloor. It provides water depths, locations of dangers to navigation, locations and characteristics of aids to navigation, anchorages, and other features.

What are types of chart in ship?

Nautical charts are usually one of three: Gnomonic (pronounced no-monic), Polyconic and Mercator. The Mercator projection is the most common.

How do you read a sea chart?

Read the chart numbers to figure out the water’s lowest depth. The black numbers printed on the chart represent water depth. Each number indicates the “mean lower low water” (MLLW) in an area. This is the average water depth at low tide, so most of the time the water is deeper than what you see on a chart.

What is coastal chart?

[′kōst ‚chärt] (navigation) A nautical chart for use in inshore, coastwise navigation when a course carries a vessel inside outlying reefs and shoals, for use in entering or leaving bays and harbors of considerable size, or for use in navigating larger inland waterways.

What is ENC and RNC?

Many Canadian Hydrographic Service (CHS) charts are available in digital form as either a Raster Navigational Chart (RNC) or as a vector Electronic Navigational Chart (ENC). Both charts use navigation software to provide navigators with an electronic alternative to paper charts, resulting in safer navigation.

What unit of measurement is used at sea?

Nautical miles are used to measure the distance traveled through the water. A nautical mile is slightly longer than a mile on land, equaling 1.1508 land-measured (or statute) miles. The nautical mile is based on the Earth’s longitude and latitude coordinates, with one nautical mile equaling one minute of latitude.

What is nautical scale?

The scale of a nautical chart is a way to convert inches on paper to inches in the real world. Chart scales are expressed as ratios (1:100,000 for example), so the unit of measure does not matter. On a chart whose scale is 1:100,000, one inch on paper represents 100,000 inches in the real world.

What do the numbers on nautical charts mean?

Numbers on a nautical chart are depth measurements. Soundings, or water depth measurements, are represented by numbers on nautical charts. Water depths are measured by soundings usually acquired by hydrographic surveys. The depths may be in either feet or fathoms (the chart will indicate which).

What are the colors found on a nautical chart?

The NOS uses various shades of five colors on their regular charts: land areas are shown in buff or yellowish color; water areas are shown in white except in shallow regions which are shown in blue; submerged areas which at times uncover at some tidal stages are shown in green.

What is the purpose of coastal charts?

Nautical charts are maps of coastal and marine areas, providing information for navigation. They include depth curves or soundings or both; aids to navigation such as buoys, channel markers, and lights; islands, rocks, wrecks, reefs and other hazards; and significant features of the coastal areas,…

What is Underscale and Overscale?

In the case of overscale, the display is “zoomed in” too close, beyond the standard of accuracy to which the data was digitized. Underscale indicates that larger scale data is available for the area in question.