British admiralty charts in U.S. waters

That doesn’t seem correct. Wouldn’t the BA just use NOAA hydrographic data, satellite imaginary etc instead? I don’t know for a fact but I’d assume that’s how it’s done.

NOS Hydrographic Survey Data

Looks like we’re both right, they do have some coverage the US already canceled, but BA coverage of US waters does seem to be limited. I have held in my hands the BA reproductions where it was just the NOAA PDF on Admiralty watermarked paper, I doubt those are being maintained. I don’t know if they used to have better coverage, I haven’t been following their catalogue closely.

I suspect it has something to do with 33 CFR 164

§ 164.33 Charts and publications.

(b) As an alternative to the requirements for paragraph (a) of this section, a marine chart or publication, or applicable extract, published by a foreign government may be substituted for a U.S. chart and publication required by this section. The chart must be of large enough scale and have enough detail to make safe navigation of the area possible, and must be currently corrected. The publication, or applicable extract, must singly or in combination contain similar information to the U.S. Government publication to make safe navigation of the area possible. The publication, or applicable extract must be currently corrected, with the exceptions of tide and tidal current tables, which must be the current editions.

(c) As used in this section, “currently corrected” means corrected with changes contained in all Notices to Mariners published by the National Geospatial-Intelligence Agency, or an equivalent foreign government publication, reasonably available to the vessel, and that is applicable to the vessel’s transit.

Given NTM information is a little funky right now while charts are being phased out, I’m not sure they could get T&Ps and corrections out for the charts that no longer exist. If it wasn’t like $50 I’d order BA 3684 and compare notes.

IDK but it strikes me as not very plausible the British Admiralty would just copy NOAA charts.

The entire rational of hydrographic agencies using international data standards and file formats is so they can use hydrographic survey data from another charting agency.

Easiest and quickest way to check is see if the scale and extent of the charts is the same.

Charts of Portland Harbor

Not the same extent, details differ.

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