Every passage re-planned on 95 days of 2027, to answer what the tide is actually worth.
It depends entirely on the passage, and the range is enormous. Re-planning every route across 95 days of 2027, the difference between the best and worst cast-off of the same day runs from under a minute on the short Desolation Sound hops to 124 min on Campbell River → Chatham Point (Seymour Narrows). That figure comes with a catch worth reading in the same breath: 52 per cent of the cast-offs on that passage are refused outright, so it is not a saving lying there for the taking. The largest gain on a passage that refuses almost nothing is 73 min on Anacortes → Shilshole (Rosario).
The tidal rapids. On Octopus Islands → Big Bay (Hole in the Wall & Yucultas), 96 per cent of all possible cast-offs are refused outright — the water is past what the pass allows, and no boat speed changes that. There timing does not save you hours, it decides whether the passage happens at all. On an open crossing like Anacortes → Shilshole (Rosario) — which refuses 0 per cent — timing buys you 73 min instead.
Yes, and it is daylight rather than current that closes them. 23 of the 92 passages in the library have at least one month with no plannable day for a boat making 6.5 knots, and the longest — Bainbridge → Echo Bay, Sucia (Rosario) at 75.8 nm — is shut for 4 months of the year. A passage of seventy-odd miles simply does not fit between a December sunrise and sunset.
Often enough to matter. On Coal Harbour → Friday Harbor, the windows fail to line up on 44 per cent of days — each gate has its own slack at its own station, and the two drift apart by about fifty minutes a day. On those days no single departure serves both and something has to give.
Every distinct passage in the library was re-planned on 95 days spread through 2027 — one day in 4, which resolves a season rather than a tide — for a sailing boat making 6.5 knots through the water. That is the app's own planner producing its own answers, not a model of it.
One year, and it matters slightly. These are 2027 tides. The moon's orbit drifts on an 18.6-year cycle that moves current strengths by a few per cent, so the same analysis for a different year would shift these minutes a little. The shape — which passages care about timing and which do not — is not sensitive to that.
Wind is deliberately absent. No forecast reaches a year ahead, so every figure here is the app's tides-only mode: what the water alone does to a passage. That is what makes months comparable, and it means a real summer afternoon in the Strait of Juan de Fuca will be slower than these numbers suggest. One boat, one year, no weather — the shape is right and the minutes are not promises.
The obvious measure is hours: the gap between the best and worst cast-off of the same day. It tells the whole story on an open passage and almost none of it at a rapid, where the planner has already refused every departure but the few near slack, so the survivors all take about the same time. Octopus Islands → Big Bay (Hole in the Wall & Yucultas) measures 1 min of spread and refuses 96 per cent of its cast-offs. Timing there is not saving you time. It is the difference between going and not going.
| Passage | Distance | Best vs worst cast-off |
|---|---|---|
| Campbell River → Chatham Point (Seymour Narrows) | 20.4 nm | 124 min |
| Refuge Cove → Big Bay (the Yucultas) | 20.8 nm | 85 min |
| Refuge Cove → Dent Island Lodge ** | 24.3 nm | 82 min |
| Anacortes → Shilshole (Rosario) | 58.4 nm | 73 min |
| Friday Harbor → Shilshole * | 59.4 nm | 67 min |
| Everett → Friday Harbor (Admiralty) * | 58.0 nm | 67 min |
| Gig Harbor → Olympia (the Narrows) | 28.1 nm | 65 min |
| Bainbridge → Friday Harbor * | 65.1 nm | 63 min |
| Tacoma → Olympia | 31.6 nm | 58 min |
| Everett → Port Townsend | 34.2 nm | 57 min |
| Roche Harbor → Shilshole (Haro) | 69.3 nm | 56 min |
| Pirates Cove → Nanaimo (2nd stage) | 11.0 nm | 55 min |
Median across the sampled days, comparing only cast-offs the planner would actually allow.
| Passage | Distance | Cast-offs refused |
|---|---|---|
| Octopus Islands → Big Bay (Hole in the Wall & Yucultas) * | 8.3 nm | 96% |
| Porpoise Bay → Egmont (Skookumchuck) | 17.8 nm | 81% |
| Prideaux Haven → Dent Island Lodge ** | 31.2 nm | 78% |
| Refuge Cove → Dent Island Lodge ** | 24.3 nm | 77% |
| Refuge Cove → Octopus Islands (Surge Narrows) | 20.1 nm | 77% |
| Egmont → Chatterbox Falls | 33.7 nm | 77% |
| Refuge Cove → Big Bay (the Yucultas) | 20.8 nm | 71% |
| Campbell River → Chatham Point (Seymour Narrows) | 20.4 nm | 52% |
| Deer Harbor → Nanaimo (via Bedwell) | 54.3 nm | 39% |
| Friday Harbor → Nanaimo (via Bedwell) | 56.1 nm | 36% |
| Reid Harbor → Nanaimo (via Bedwell) | 46.3 nm | 36% |
| Sidney BC → Nanaimo | 43.1 nm | 36% |
Share of departures refused outright for current, depth or sea state, counted only over cast-offs that get in before dark — the planner draws a couple of hours past that to show the door closing, and counting those made long passages look fussier than they are. 33 of 92 passages refuse anything at all; the other 59 can be taken at any hour the light allows.
23 of 92 passages have at least one month in which no departure works. The cause is daylight, not current: the tides run on lunar cycles and do not care what month it is, but a seventy-mile passage at 6.5 knots does not fit inside a December day.
| Passage | Distance | Closed |
|---|---|---|
| Bainbridge → Echo Bay, Sucia (Rosario) * | 75.8 nm | Jan, Feb, Nov, Dec |
| Bainbridge → Sidney BC | 79.0 nm | Jan, Feb, Nov, Dec |
| Sidney BC → Shilshole (Haro) | 75.9 nm | Jan, Feb, Nov, Dec |
| Port Townsend → Neah Bay *** | 79.7 nm | Jan, Feb, Nov, Dec |
| Reid Harbor → Shilshole * | 68.9 nm | Jan, Nov, Dec |
| Sucia Island → Shilshole * | 72.6 nm | Jan, Nov, Dec |
| Edmonds → Echo Bay, Sucia (Rosario) * | 66.0 nm | Jan, Nov, Dec |
| Bainbridge → Roche Harbor (Haro) | 72.5 nm | Jan, Nov, Dec |
| Edmonds → Sidney BC | 69.2 nm | Jan, Nov, Dec |
| Bainbridge → Victoria | 69.3 nm | Jan, Nov, Dec |
A passage with more than one gate has more than one slack to hit, and they drift apart by about fifty minutes a day. These are the passages where that becomes a problem, and how often.
| Passage | Gates | Days the windows conflict |
|---|---|---|
| Coal Harbour → Friday Harbor * | 2 | 44% |
| Coal Harbour → Sidney BC * | 2 | 40% |
| Coal Harbour → Roche Harbor * | 2 | 37% |
| Octopus Islands → Big Bay (Hole in the Wall & Yucultas) * | 2 | 0% |
| Refuge Cove → Dent Island Lodge ** | 3 | 0% |
| Prideaux Haven → Dent Island Lodge ** | 3 | 0% |
The three-rapid runs above Desolation Sound never conflict: the Yucultas and Gillard share a current station, so their slacks are minutes apart rather than hours. Conflict is a property of gates far enough apart to have independent tides.
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