Surveys & Wrecks  
  Hydrographic Products  
     •   Survey Data  
     •   Wrecks and Obstructions  
  Standards and Requirements  
     •   Field Procedures Manual  
     •   Specifications and Deliverables  
     •   XML Hydrographic Reports  
     •   Hydrographic Survey Manual  
     •   IHO Standards  
     •   Survey Vessels  
     •   Hydrographic Survey Priorities  
     •   Contract Hydrographic Surveys  
  Learn About Hydrography  
     •   What is Hydrographic Surveying?  
     •   History of Hydrographic Surveying  
     •   Side Scan Sonar  
     •   Multibeam Echo Sounders  
     •   LIDAR  
     •   Horizontal & Vertical Positioning  
     •   Dangers to Navigation: Notice to Mariners  

Wrecks and Obstructions Database User's Guide

This website provides information about the background and limitations of the Wrecks and Obstructions Database. In addition, details of the attributes of the wrecks and obstructions data sets are provided.

Background and Limitations

Historically, NOAA has maintained two separate sources of information on wrecks and obstructions.

  • The Automated Wreck and Obstruction Information System (AWOIS) database was established in 1981 to help estimate the level of effort required for investigating items within the limits of a planned hydrographic survey. However, because of the emphasis is on features which are most likely to pose a hazard to navigation, AWOIS has limitations. Most notably, AWOIS is not a comprehensive record and does not completely address every known or reported wreck. Additionally, for a number of reasons, AWOIS positions may not agree with a charted position for a similar feature.

  • NOAA ENC®s (electronic navigational charts), first developed in 1997, have been compiled from authoritative source on features (including shipwrecks) that are navigationally significant, and they provide the official chart data used in Electronic Chart and Display Information Systems (ECDIS). ENCs are the authoritative source of information about known or reported wrecks and are much more comprehensive than AWOIS. However, the features in an ENC lack the historic information and context that is provided by AWOIS.

Record Attributes

Each record has a series of attributes, which provides information about the wreck or obstruction. These attributes are listed below, along with their descriptions.

Attribute Title/
Description Examples

(AWOIS Only)
Unique numerical record identifier (East Coast: 1 - 49,999, West Coast: 50,000 +). 658

Name of the vessel (if known) or the terms UNKNOWN or OBSTRUCTION. LILLIAN
Describes the physical characteristics of the feature. Wreck - Submerged, dangerous
Wreck – Submerged, nondangerous
Wreck - Visible
Not Charted
Obstruction - Covers/uncovers
Latitude in decimal degrees using the North American Datum of 1983 (NAD83). 41.829972
Longitude in decimal degrees using the North American Datum of 1983 (NAD83). -70.143028
Positional Accuracy

(AWOIS Only)
An indicator of the relative positional quality of the feature. A description of positional accuracy categories is provided below. High
Position Source

(AWOIS Only)
An indicator of the method in which the position was derived from the source document. Options include:
Scaled: scaled from a hard copy or from a digital image,
Direct: Transcribed directly as reported in the source document.
Actual least depth or wire drag cleared depth over a feature that has been determined by hydrographic or wire drag survey methods.

ENC Depths are always reported in meters. For AWOIS items, the units are indicated by the attribute Depth Units.
Depth Units
Indicates the units in which the least depth over the feature has been determined. Feet and tenths
Fathoms and tenths
Meters and tenths
Wire-drag clearance, feet
Wire-drag clearance, fathoms
Year Sunk

(AWOIS Only)
The year in which the vessel was sunk, if known or the term None if unknown. 1924

Memo field that contains additional information about the feature.

For AWOIS features, entries in this category may be or unreliable. Common codes in AWOIS histories include hydrographic survey registry numbers (e.g., H-9872/79), shoreline manuscript registry numbers (e.g., TP-00278), miscellaneous document numbers (e.g., CL980/76 and BP100234), and U.S. Coast Guard Local Notices to Mariners (LNM).

Any positions in the History memo field are for reference purposes only and will have generally been superseded by the positions in the Latitude and Longitude fields.
OPR-B301-RU-07-- 36 ft wreck; This wreck was submitted as a DTON by the field party on April 26th, 2004. This wreck is shown on chart 13223, 38th Edition, April 2005, and has been applied to the continual maintenance raster dated August 29th, 2006 (RES 10/26/07).
Sounding Quality

(ENC Wrecks Only)
Indication of the reliability of the value of sounding over the wreck. depth unknown
least depth known
value reported (not confirmed)
Water Level Effect

(ENC Wrecks Only)
Indicates the effect of the surrounding water on the wreck. always dry
always under water/submerged
covers and uncovers

Positional Accuracy (AWOIS only)

  • High: A high quality position originating from a survey source or whenever there is a high level of confidence that the wreck or obstruction may be relocated without unreasonable difficulty. Although most positions in this category originate with NOS surveys, other sources may qualify, as long as the originating authority has the capability to do high quality work. Authorities such as the U.S. Army Corps of Engineers and private surveyors are selected examples.

  • Med: A probable high quality position, such as that originating with a survey but lacking supporting documentation. Positions originating from non-agency sources may also be in this category if the location is tightly controlled by adjacent features such as pier lines or fixed aids to navigation. A report that the wreck or obstruction has been actually located by the Coast Guard or Corps of Engineers will usually qualify a position for this category. In some cases, the item may be charted with an approximate position (PA) notation.

  • Low: A position of questionable or unverified quality. Most reports from Local Notice to Mariners and private observers are of this type. If the reported position is expressed a range and bearing from an identifiable fixed feature and is near shore relative to the position fixing method, it will probably be included in this category. If the position fixing method is unknown, it is assumed to be visual. The nautical chart may indicate an approximate position (PA) for this item.

  • Poor: A position of doubtful quality usually referenced to some general shoreline feature or portion of shoreline. The nautical chart may indicate an approximate position (PA) or a position doubtful (PD) for this item.

AWOIS Acronyms and Abbreviations

NOAA has provided a list of acronyms and abbreviations which are commonly used in the AWOIS records.

Wrecks and Obstructions Database Inquiries:

For any questions, comments, or concerns related to the Wrecks and Obstructions Database, please submit an inquiry

User Survey  | Privacy Policy  |  Disclaimer  |  NOAA's National Ocean Service  |  NOAA  |  U.S. Department of Commerce 
Web site owner: NOAA Office of Coast Survey