Shallow-Water Warnings From Your iPhone and Apple Watch, Set to Your Boat’s Draft

Both will, once Wavve Boating knows your draft: the shallow-water alerts on your iPhone adjust to the draft you enter, and an Apple Watch paired with that iPhone adds haptic warnings on your wrist as you approach shallow water.

The chart reads from that same entry, which Wavve defines as the vertical distance from the top of the water to the bottom of your boat. The Wavve Boating Map is personalized to it and uses red shading for potentially shallow areas. A flats skiff drawing eighteen inches will see red mostly along the bars and the edges of the flats, and a cruiser drawing four feet will see a good deal more of the same bay marked. Wavve started from exactly this problem: founder Adam Allore, a lifelong boater, built a map that highlighted the water too shallow for his own boat’s three-foot draft.

On the iPhone, the shallow-water alerts come from the same app that shows you that red shading, and the map is designed to remain clear in bright sunlight, which matters on an open boat at midday. The chart is still something you have to look at, though. On plenty of boats the phone sits in a mount behind a windshield or under a T-top while you watch the water ahead, the engine is running, and people aboard are talking over it, so a change in the shading can go unseen for a while.

That is the gap the Apple Watch fills. As you approach shallow water, it gives you a haptic warning on your wrist, which you feel even while your eyes are on the bow and not on the mount. You can also use the Digital Crown to control the map while you are moving, without reaching for the phone. The watch works as a companion to the iPhone app and does not navigate as a separate device.

You do not need an Apple Watch for the draft-based alerts. Without one, the alerts and the red shading on the iPhone give you the same draft-based picture of the potentially shallow areas ahead.

Two display settings on the phone are worth a minute before your first run with a mounted screen. Depth contours can be given custom colors, and the size of the soundings can be adjusted, so the depth detail around a channel edge or a shoal is as easy to pick out at arm’s length as you want it to be.