Swell Signal

Every big ship in Puget Sound, tracked live, with the time its wake reaches your beach. Widgets for the next boat, the tide and the wind. Free, no ads.

Big ships make rideable waves. Swell Signal tells you which ones, where the wave lands, and what time to be standing on the beach.

I built it at Three Tree Point in Burien, Washington, after too many afternoons of guessing. A container ship would go by, the water would come alive twenty minutes later, and half the time I was still in the car. So the app watches every large vessel in Puget Sound over live AIS, runs real ship wake physics on each one, and puts the answer on your Lock Screen: the boat, how good the wave should be, and the clock time it passes your spot.

WHAT YOU SEE WHEN YOU OPEN IT A dark nautical chart of the Sound with every tracked ship on it. Tap one and you get its name, size, speed through the water, heading, the wake it is throwing right now, and a 3D view of that wake so you can see the shape of what is coming. The headline is always a time, like "2:20 PM, in 18 min", because that is the only number that matters when you are deciding whether to grab the board.

Ship traffic comes in bursts. When nothing is coming the app says so, and the tide and wind are right there so the trip is not wasted.

PICK THE SPOTS YOU RIDE Drop a pin anywhere on the water and Swell Signal forecasts for that exact point: which ships matter, when their wake arrives, and how good it should be. Save up to twelve. Your location is only read if you tap the button, and only to place the marker, which you can then drag anywhere.

ALERTS THAT LEAVE YOU ALONE Set a quality bar and quiet hours. You get a push when a wave worth moving for is on its way, and nothing at 3 a.m. unless you asked for it.

TIDE, DONE PROPERLY NOAA tide predictions for the beaches you choose, with a curve you can scrub through, thirty days of highs and lows, the tidal current and slack water, sunrise, sunset and the moon. The first time you open the tab it asks where you watch the tide and remembers.

WIND YOU CAN TRUST A blend of forecast models corrected against what the local buoys actually recorded, because the models under-call wind on the water here and anyone who has been skunked at the beach knows it. A beginner view that gives the short answer, and an expert view with every model laid out.

WIDGETS FOR EVERYTHING Next Boat, Tide, Wind, and a Swell Board that puts all three together. Small, medium and large, plus the Lock Screen sizes. Glance, do not open.

THE FERRIES TOO Washington State Ferries are on the chart with their sailings, because a ferry wake at the right spot on the right tide is a real ride.

RATE THE WAVE After a predicted wave passes, the app asks how it was. Three sliders, ten seconds. Every rating feeds back into the model for that spot. The physics started from published ship wake research and has been tuned by riders reporting what actually happened at Three Tree Point, and it keeps being tuned.

DISPLAY MODE Turn a spare iPad into a wall display of the next boat, the tide and the wind. Good for the garage where the boards live.

HONEST ABOUT WHAT IT IS Free. No ads, no analytics, no tracking. An account is optional and only needed to rate waves or sync your pins across devices. It is a handle and a password, nothing else, and you can delete it from Settings whenever you like.

It covers Puget Sound, Washington, because that is where it was built and where the vessel data is paid for. If you ride somewhere else and want it there, tell me through the feedback form.

A forecast is not a safety system. Ship wakes come from working vessels in shipping lanes. Keep well clear of traffic, read the water yourself, and treat every prediction as a maybe.

Tides and currents from NOAA. Ferries from WSDOT. Vessel positions from AIS. Wind from the National Weather Service, the forecast models and the buoys of Puget Sound.