Maritime Safety Information

How often is the data on the Web site updated?
The answer depends on the type of data...

Data associated with the Notice to Mariners (PDF files, correction databases, graphic correction files, etc.) is updated weekly, usually by Friday evening.

The Broadcast Warnings, Anti-Shipping Activity Messages (ASAM), and Mobile Offshore Drilling Units (MODU) databases are updated daily, usually before 1200 ET.

New editions of digital publications and new PDU files are uploaded as soon as they become available.

Where are the Summary of Corrections publications?
The Summary of Correctionsare not posted to this site as PDF files due to their enormous file sizes, often exceeding 200MB per Volume when including the graphic corrections. However, all of the information contained within the five Summary of Corrections Volumes is available by database query from the Notice to Mariners section of this Web site.

Where do I find Publication Data Update (PDU) files?
Publication Data Update files, or "PDU" files, are found in the Publications section of this Web site, on the same page as the type of publication to which they apply. For instance, PDU files for Sailing Directions Enroute are accessed from the Sailing Directions Enroute page.

If no PDU file is listed for a specific publication, then a PDU file has not yet been issued for that publication.

What does it mean when a correction refers to "Subsection I-2"?
Subsection I-2 refers to that section of the Notice to Mariners publication where any associated graphic corrections appear. This Subsection is also referred to as the "Chartlets/Depth Tabulations/Notes" section.

To download associated graphic corrections using the Notice to Mariners database query form, change the "Notice to Mariners (NtM) Query:" list selection from "Chart Corrections" to "Chartlets/Depth Tabulations/Notes" and enter the appropriate chart number/NTM number information.

Why can't I print chartlets at the correct size?
Select the Printing Instructions hyperlink on the Home page to view detailed instructions for printing graphic chart corrections (chartlets, depth tabulations, notes).

How do I report a discrepancy?
The "Marine Information Report and Suggestion Sheet" form included in each issue of the Notice to Mariners has long been used to submit discrepancies noted on NGA nautical products. The same form can now be submitted electronically from the Submit Reports section of this Web site.

Discrepancy information can also be submitted by e-mail to the site's Webmaster account at webmaster_nss@nga.mil.

Discrepancies noted on charts produced by NOAA should be sent directly to NOAA's Office of Coast Survey by completing their electronic Discrepancy Report form.

Where can I get NGA charts and publications?
For information about ordering NGA nautical products, visit the Product Catalog section of this Web site.

Why does my database query take so long?
Due to the high demand, our database server may occasionally become slow or unresponsive. Please be patient as your query request is being processed.

Certain database queries, by their very nature, will also require additional processing time. For instance:
- Queries "by Geographic Area" must search an entire database of coordinate data to locate the matching coordinates.
- Using the query option "All" will obviously require more processing time than using more specific product number or NTM number options.
Generally speaking, the more specific information that is provided when submitting a query to the database, the faster the response time will be.

Why do I occasionally have problems connecting to your server?
At times, we experience network outages, bandwidth issues, and/or hardware failures. Please be patient and try to connect again later. If you continuously experience difficulties connecting, send an e-mail message describing the problem to this site's Webmaster at webmaster_nss@nga.mil.

Why am I getting a "Module may not support this view" error message?
We have been unable to determine the root cause of this problem, but have found that it is usually isolated to only one of our four Web servers.

When this problem occurs, you may be able to connect to one of the other three servers by closing and restarting your Internet browser software and reconnecting to this Web site.

What is "HarborView" and where can I get it?
HarborView is a high-resolution, interactive 3-D scene visualization application that allows users to virtually navigate through more than 125 seaports worldwide. HarborView can provide port familiarization, exercise and rehearsal capabilities, mission planning and information for use in force analysis and threat protection.

The HarborView product is designed as a stand-alone application and can be loaded onto any desktop or laptop computer equipped with the following minimum requirements: Microsoft Windows 98, 512 Mb RAM and a 64Mb graphic accelerator card.

HarborView is only available to US government and military personnel. Additional information and requests for the HarborView scene viewer and available port models can be submitted to harborview@nga.mil or by contacting Len Kobus, NGA HarborView Team Chief, at (301)227-6586.