Staying alive on Superior
This lake holds more water than the other four Great Lakes combined and it does not behave like an inland lake. Most of what goes wrong here comes down to four things people consistently underestimate.
1. The water is cold enough to kill you in July
Superior averages around 4 C year round and only the surface warms. A 27 C afternoon can sit on top of 8 C water. Air temperature tells you nothing about what happens when you go in, and almost everybody dresses for the air.
| Water temperature | What happens | Useful time |
|---|---|---|
| Under 5 C | Immediate cold shock. Involuntary gasp, hyperventilation, no breath control. | Minutes |
| 5 to 10 C | Cold shock, then rapid loss of hand and arm function. | 10 to 15 minutes of useful movement |
| 10 to 15 C | Manageable if you are calm and wearing a PFD. Swimming ability drops fast. | Well under an hour |
| Over 15 C | Survivable for a while, still cold enough to sap you. | One to several hours |
Right now at Shuniah, Ontario the water is about 14 C. Genuinely cold. Survivable, but assume well under an hour before you cannot help yourself.
2. Fetch matters more than wind speed
Fetch is the distance the wind travels over open water before it reaches you. It is the single biggest reason two spots on the same lake, in the same wind, have completely different water. This is what the forecast on this site actually computes: it walks upwind across the shape of the lake from your exact position until it hits land.
| Fetch | Waves at 20 knots | What that means |
|---|---|---|
| 5 km | 0.4 m (1.2 ft) | Comfortable on anything |
| 15 km | 0.6 m (2.1 ft) | Choppy on a sea-doo, fine in a boat |
| 40 km | 1.0 m (3.4 ft) | Getting unpleasant on small craft |
| 100 km | 1.6 m (5.4 ft) | Experienced boaters only |
| 200 km+ | 1.9 m (6.1 ft) | Stay in |
This is why Thunder Bay behind the Sibley Peninsula, the Keweenaw Waterway, Chequamegon Bay and Munising Bay stay rideable when the open lake does not. The spots page ranks every one of them for the wind you have right now.
3. An offshore wind lies to you
When the wind blows from the land out over the water, the chop has not had any fetch to build in yet, so the beach looks calm. Every kilometre you travel out, the water gets worse and the wind gets stronger, and every one of those kilometres has to be fought back into a headwind on the way home. This is the classic way paddlers and sea-doo riders end up needing rescue on this lake. The forecast flags it explicitly when the wind is offshore where you are.
4. Squalls arrive faster than you can get in
A line of storms crossing Superior can put 40 knots and two metres of water on top of you inside fifteen minutes, and on open water you are the tallest thing for kilometres. The forecast here tracks convective energy hourly and caps the verdict whenever storms are possible, but the rule on the water is simpler: watch the western sky, and if it goes dark and the wind switches, you are already late.
Before you launch
Wear the PFD. Not stowed. Worn. Cold shock happens too fast to put one on.
Tell somebody your plan. Where you are launching, where you are going, and when you will be back.
Check the wind direction, not just the speed. It decides your fetch, and it decides whether you are being blown offshore.
Pick a bail-out shore. Before you leave, know which way you run if it builds.
Dress for the water, not the air. A wetsuit in August is not overkill on this lake.
Carry a way to call for help. A VHF beats a phone. Cell coverage on the north shore and around Pukaskwa is patchy to nonexistent.
Watch the western sky. Squalls come from there and they come fast.
Turn around earlier than feels necessary. The trip home is always into what built while you were out.
If it goes wrong
Call 911, or hail the Coast Guard on VHF channel 16. Both the Canadian and United States Coast Guards monitor it across the lake.
Stay with the boat. A hull is far easier to spot than a head, and it keeps more of you out of the water.
Ride out the first minute. Cold shock passes in about sixty seconds. Hold on, do not thrash, and wait for your breathing to come back before you do anything else.
Get as much of you out of the water as you can. On the hull, on the board, on anything. You lose heat many times faster in the water than in the air.