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Hydrographic Notes

Inform us of navigationally significant information

ADMIRALTY Hydrographic Notes

​Hydrographic Notes allow you to inform us of any navigationally significant information. This information could include new or suspected dangers, changes to navigational aids, amendments to details included in publications and suspicious charts or publications that could be counterfeit.

These can be sent in paper format (as outlined below) or sent using the ADMIRALTY H-Note App.

For emergency information affecting safety of life at sea, forward to:

Alternatively, contact T:+44 (0)1823 353448 (direct line) or F: +44 (0)1823 322352.

What to include in Hydrographic Note submissions

The Hydrographic Note forms below contain information to help you complete any submission. These details are also included within Chapter 8 of the Mariner's Handbook (NP100). Please note that you should also contact the originating hydrographic office when navigating on IMO-approved, non-ADMIRALTY nautical charts.

Find out more about the Mariner's Handbook (NP100) >


Downloading and sending Hydrographic Note forms

Each of the a forms below contain accompanying instructions to help you complete any submissions. Simply choose the type of information you'd like to send and download the corresponding form.

H102 - Hydrographic Note (with instructions) for General Information 

H102A - Hydrographic Note (with instructions) for Port Information 

H102B - Hydrographic Note (with instructions) for GNSS observations against corresponding chart positions 

H634 - Ornithological Log 

H636 - Marine Bioluminescence Observations reporting form 

H637 - Marine Life / Fishing Activity reporting form 


Please email your completed form to: or by send it via fax: +44 (0)1823 352561. For urgent information contact F: +44 (0)1823 322352 or send by email.

Once we’ve received and processed your data, we’ll acknowledge receipt of it by post or email.


Supporting information

Chart images and photographs - sent either with the hard copy or as attachments to the electronic copy - will help us to clarify your report.

Any format is acceptable. Those most commonly used are JPEG, TIF and AutoCAD. File sizes of the Hydrographic Notes range from approximately 61Kb to 70Kb; however the size of a returned email would depend on any additional attachments that have been made.

The ADMIRALTY H-Note App helps you to send the UKHO reports on suspected dangers to navigation or changes observed in aids to navigation using a mobile device. Free to download and easy to use, the application takes advantage of your mobile’s built-in camera and GPS to help gather important navigational information and to email it to the UKHO once your vessel is in a Wi-Fi or cellular coverage area.

When you submit an H-Note via the App, you will receive an acknowledgement. The information you send will be used by the UKHO to take immediate action or considered for use in the next appropriate revision of a chart or publication.

Download the H-Note App Legal Agreement 


Downloading the H-Note App

The H-Note App is available for free on iPhone, iPad and iPod touch. It can be downloaded on the App Store:

Download the H-Note App on the iTunes store >