Chart coverage by US region

Helm ships one chart pack per region rather than one file for the country, and every pack is built from the official NOAA electronic navigational charts for that water. This page is the count: what is actually inside each one.

Helm has 31 coastal and Great Lakes chart packs for US waters. The 18 below have a page each, and the others cover Alaska, Hawaii, Puerto Rico and the US Virgin Islands, Guam and the Northern Marianas, American Samoa, Miami and Biscayne Bay, Charleston to Hilton Head, the Central California Coast and the Oregon Coast. Across the 18 coastal and Great Lakes regions below that comes to 3,619 NOAA ENC cells, 1,779,050 individual charted soundings, 16,763 charted wrecks and 2,299 NOAA tide prediction stations. Pick your water to see what its own pack carries and what the numbers mean once you are out in it.

Region	ENC cells	Soundings	Wrecks	Tide stations
New England
Massachusetts & Boston	179	115,953	707	100
Maine Coast	151	121,067	202	118
Northeast
Long Island Sound & NY	234	201,800	2,836	180
New Jersey Shore	146	75,848	1,763	216
Mid-Atlantic
Chesapeake Bay	237	141,077	1,673	217
Southeast
Carolinas & Outer Banks	268	72,982	720	142
Georgia & Savannah	91	44,839	227	115
Florida
Florida East Coast	242	130,555	1,015	351
Florida Gulf Coast	168	115,701	874	211
Gulf
Alabama-Mississippi-Louisiana	357	115,671	2,447	137
Texas Coast	213	74,056	1,103	79
Florida Panhandle	107	55,980	490	79
West
Puget Sound & PNW	219	103,658	457	178
San Francisco & NorCal	112	51,821	497	137
Southern California	76	62,883	269	39
Great Lakes
Lakes Huron & Superior	372	130,063	579	no tide
Lake Erie & Ontario	246	89,773	427	no tide
Lake Michigan	201	75,323	477	no tide

Counted layer by layer from the chart packs themselves. The Great Lakes have no meaningful astronomical tide, so no prediction stations are listed for them.

Inland lakes and rivers

The regions above are the coastal and Great Lakes packs. Inland water is packed separately. The commercial rivers each get their own pack and their own count, on the rivers page, and the state lake packs draw lake shorelines from USGS data without depth, with contour lines added only in Minnesota, as the lake charts by state pages explain.

Common questions

How is Helm's US coverage split up?

Helm builds one chart pack per region rather than one file for the whole country, so you download the water you actually run. The 18 coastal and Great Lakes packs on this page are built from 3,619 official NOAA electronic navigational chart cells between them.

Do I need to download a pack to use Helm in my area?

No. Charts stream while you have a signal. The pack is what keeps charts, depth, tides and the anchor alarm working when the signal goes, which on most of this water is a question of when rather than if. Every pack on this page except Lakes Huron and Superior also carries routing data, so route planning keeps working too.

Where do the numbers on these pages come from?

Every count is taken from the chart pack itself, layer by layer, out of the official NOAA ENC releases the pack is built from. Nothing on these pages is an estimate.