NOAA Chart Tile Service

The NOAA Chart Tile Service provides standardized nautical chart tilesets for the public, eliminating the need for application developers to regularly undergo the cumbersome process of transforming NOAA BSB files into tilesets. It provides geo-referenced charts compatible with the Web Map Tile Specifications (WMTS) and Tile Map Service Specification (TMS). All tilesets are published on a weekly basis.

Provides the following capabilities:

- Generates geo-referenced single Chart Tilesets from NOAA BSB files. The tileset representing a single NOAA chart at multiple zoom levels.

- Provides a description of all available tilesets.

- Demonstrates single Chart Tileset compatibility with popular mapping APIs.

- Supplies source code describing tileset integration with each API.

- Provides a searching capability for kaps/tilesets with a zoom to tileset feature.

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The Nautical chart features are according to the U. S. Nautical chart symbols, abbreviations and terms which are Chart No. 1. The NOAA charts are built and maintained according to the policies and procedures documented in the two volumes of the Nautical Chart Manual. The Marine Chart Division, Quality Assurance Policy and Standards Branch (QAPSB) manages questions in reference to symbols, abbreviations, policy and procedures.

http://chartmaker.ncd.noaa.gov/mcd/chartno1.htm

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To be used for navigation and/or as per agreement with the NOAA RNC chart distributor and distribution network.

The Nautical chart features are according to the U. S. Nautical chart symbols, abbreviations and terms which are in Chart No. 1. Chart 1 can be found at http://chartmaker.ncd.noaa.gov/mcd/chartno1.htm.

The NOAA charts are built and maintained according to the policies and procedures documented in the two volumes of the Nautical Chart Manual. Questions in reference to symbols, abbreviations, policy and procedures are managed by the Marine Chart Division, Quality Assurance Policy and Standards Branch (QAPSB). For inquiries visit: http://ocsdata.ncd.noaa.gov/dr/inquiry.asp

The art and science of navigation, piloting, and chart making has not been immune to the effects of technology.Prior to 1995, The paper charts were composed manually. In 1995 the paper charts were scanned to create the raster charts. Both, the paper and raster charts are composed from the same digital files.The availability of digital chart products and Differential Global Positioning System (DGPS) has drastically changed navigation. Navigation systems using DGPS for locating a vessel's position on the earth have put mariners in a unique predicament due to a false perception of greater positional accuracy of features portrayed on the charts. In many cases, the DGPS is more accurate than the surveying technology that was used to put the soundings and features on the nautical chart, paper or raster. This discrepancy is even more pronounced when chart scale is taken into consideration. On a 1:40,000 scale chart, a feature could have a potential error of 40 to 80 meters (about 130-160 feet) due to scale alone. This is often the cause of the "ship on the pier" situation, where the vessel tied up at the pier appears on the navigation system to be on the pier rather than alongside.Another source of this type of discrepancy is that symbols on a chart of a given scale may be a representation for multiple real features that are too close together to be shown at chart scale. Similarly, symbols may be displaced from their original location for legibility and presentation. This also applies to products derived from paper charts, such as raster charts and vector charts created by digitizing the paper chart The NOAA Nautical Chart Manual has an extensive description of the horizontal datum.

Nautical Charts are navigational tools. Thus, depths are biased for navigation purposes. Charts use multiple vertical datums (Mean higher high water [MHHW]; Mean high water [MHW]; Mean sea level [MSL]; Mean low water [MLW]; Low water datum [LWD]; Mean lower low water [MLLW]; Gulf Coast low water datum [GCLWD].) The NOAA Nautical chart manual has an extensive description of the vertical datum used. Sounding datums used in coastal areas for nautical charting are determined by local observations, ideally over a period of 19 years. The official time period over which tide observations are taken to obtain mean values for tidal datums has been standardized by NOS. The present National Tidal Datum Epoch is from 1983 through 2001. There have been three epochs used previously over the past century: 1924 through 1942, 1941 through 1959, and 1960 through 1978. The individual chart title block documents the datum used for that chart.

The charts are navigational tools. Sounding datums used in coastal areas for nautical charting are not referred to the 1929 datum but are determined by local observations, ideally over a period of 19 years. The official time period over which tide observations are taken to obtain mean values for tidal datums has been standardized by NOS. The present National Tidal Datum Epoch is from 1983 through 2001. There have been three epochs used previously in the past century: 1924 through 1942, 1941 through 1959, and 1960 through 1978. The individual chart title block documents the datum used for that chart. Charts use multiple vertical datums (Mean higher high water (MHHW); Mean high water (MHW) ; Mean sea level (MSL); Mean low water (MLW); Low water datum (LWD); Mean lower low water (MLLW); Gulf Coast low water datum (GCLWD). Each organization that provides source data to be applied to the chart has data acquisition and data processing and survey parameters such as vertical and horizontal datums, and quality assurance standards. The Marine Chart Division uses source data according to the policy and procedures specified in the charting manual for each source provider. The density of charting features depends on the scale of the chart or chart inset.

It is imperative to recognize that when a symbol, abbreviation, or policy changes, it does not require that all preexisting data on the charts change. Therefore, there are inconsistencies on the charts depending on policy at the time the feature was applied or updated.