Hydrographic Notes

About Hydrographic Notes

​Hydrographic Notes allow you to inform the UK Hydrographic Office 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.

How to submit Hydrographic Notes


If you have navigationally significant information to share with the UKHO, please complete the relevant Hydrographic Note form below and email it to your completed form to: sdr@ukho.gov.uk.

Alternatively a paper form can be completed and sent to the UKHO via fax or post to: 

Source Data Receipt, UK Hydrographic Office
Admiralty Way 
Fax: +44 (0)1823 322352 

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

What to include in Hydrographic Note submissions


The Hydrographic Note forms contain information to help you complete any submission. Please note that you should also contact the originating hydrographic office when navigating on IMO-approved, non-ADMIRALTY nautical charts. These details are also included within Chapter 4 of the Mariner's Handbook (NP100).

Supporting images

To help us clarify your report, you can send accompanying chart images and photographs via email or with the hard copy of your completed Hydrographic Notes form. 

We accept images in any format. 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.

Emergency information

For emergency information affecting safety of life at sea, please forward directly to: navwarnings@ukho.gov.uk 

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



Please note, the ADMIRALTY H-Note App has now been withdrawn from app stores.

Retirement of the ADMIRALTY H-Note App

The UKHO will be has retired the ADMIRALTY H-Note App as of 29 March 2024. Please use process outlined above to send us any navigationally significant information.