C-MAP 4D Asia North Continental Electronic Chart Card (microSD/SD)

The C-MAP 4D Asia North Continental chart card is a pre-loaded electronic chart for boats working the northern reaches of the Asia continental coastline. Everything lives on one small microSD card. You slot it into a compatible plotter, and the whole region comes up on the screen. No download, no cell signal, no fuss. This is the card you want in the reader before you leave the dock.

C-MAP 4D is the content set that made these cards popular with cruisers who actually run distance. You get detailed vector charts, depth contours you can read at a glance, and the kind of coastal detail that matters when you're threading an unfamiliar approach at dusk. Tides and tidal currents are built in, so you can plan a passage around the water instead of fighting it. Port and marina information is on there too, which takes a lot of the guesswork out of arriving somewhere new after dark.

The coverage is the Asia North Continental region. If you're cruising the northern Asian seaboard, running deliveries through those waters, or just planning a long passage, this is the sheet you need loaded. C-MAP publishes the exact coverage boundary on their coverage viewer, and it's worth a two-minute look before you buy to confirm your cruising grounds fall inside the box. We'd rather you check than guess.

Getting it running is about as simple as marine electronics get. The card ships as a microSD with a full-size SD adapter in the sleeve, so it fits both microSD and standard SD card slots. Push it into your plotter's chart slot, and the unit reads it on boot. One thing worth knowing from the field: some older plotters won't pick up a freshly inserted card until you power the unit all the way down and back up. If your screen doesn't see it right away, cycle the power before you assume something's wrong.

Compatibility is the part to get right. This is a C-MAP 4D card, so it belongs in a 4D-ready chartplotter with a microSD or SD card slot. Older units sometimes need a software update before they'll display the full chart, and running behind on firmware is the usual reason a card shows blank patches instead of full coverage. If you're on an older plotter, update the software first, then load the card. It saves a frustrating afternoon.

One thing boaters like about C-MAP 4D cards is that they generally aren't locked to a single plotter. That means you can pull the card and move it to another compatible unit, a handy thing if you run a card between the helm and a backup, or if you upgrade your plotter down the road. Keep the card in its case when it's out of the reader, because the contacts don't love salt air, and readers on exposed flybridge helms in the tropics are hard on everything.

The card itself weighs almost nothing, about 0.071 pounds, and it's small enough to keep a spare in the nav bag without a second thought. If you want the freshest chart edition, C-MAP lets you update the card from a PC before you install it, so it's worth doing a refresh at the start of a season rather than trusting whatever edition shipped in the box. A few minutes at the laptop now beats finding out about an old edition when you're offshore.

Bottom line: if your boat runs Asia North Continental waters and you've got a 4D-ready plotter, this card gives you the charts, depths, tides, and harbor detail you need on one microSD. It's honest, offline navigation you can count on when the signal drops and the sun's going down.