What should I watch out for at Thatcher Pass?

Lawson Rock sits in midchannel, a little under half a mile north of Fauntleroy Point. It's lit, but give it a wide berth — it's the one real obstruction in an otherwise open pass.

What does Class 2 mean?

Class 2 is BoatRoutes' own 1-to-5 rating of how costly a timing or judgment mistake is here — it is not a NOAA scale. Class 2 means one thing to plan around (depth, a schedule, or mild current); getting it wrong costs time, not safety.

Thatcher Pass — Currents, Slack & Local Knowledge

Thatcher Pass 2

Open the map ↗

Thatcher Pass runs between Blakely Island and Decatur Island and is the main ferry route between Anacortes and the San Juan Islands. It's about half a mile wide at its narrowest, and the water is deep and mostly clear of hazards.

Timing

Thatcher PassPhoto: Joe Mabel / Wikimedia Commons (CC-BY-SA-3.0)

Coast Pilot, In Plain Words

Here is what the U.S. Coast Pilot says about Thatcher Pass and the water around it. The official text is below.

Read the official text

Currents

Thatcher Pass, between Blakely Island and Decatur Island, is about 0.5 mile wide in its narrowest part. The pass is deep and free of danger with the exception of Lawson Rock, in midchannel, 0.4 mile north of Fauntleroy Point. The south point of Blakely Island and Lawson Rock are marked by lights. Thatcher Pass serves as the primary route for ferries transiting from Anacortes to the San Juan Island terminals.

Fauntleroy Point, the northeast end of Decatur Island, is marked by a light. With a south wind and ebb current, heavy rips will be encountered off the east entrance to Thatcher Pass.

Tides and currents

See the Tidal Current prediction service at tidesandcurrents.noaa.gov for specific information about the times, directions, and velocities of the current at numerous locations throughout the area, including Rosario Strait and vicinity. Links to a user guide for this service can be found in chapter 1 of this book. The currents in Lopez, Thatcher and Obstruction Passes are reported to attain velocities of 3 to 7 knots. This should be kept in mind when proceeding through Rosario Strait, particularly at night or in thick weather. On the ebb of a large tide off the entrance to the passes, a south wind causes tide rips that are dangerous to small craft. In the area northwest of Belle Rock (48°29'35".N, 122°45'10"W.), mariners may experience a strong set to the west during ebb currents flowing out of Guemes Channel.

Source: U.S. Coast Pilot 10, Chapter 7, 7 ed. (NOAA, Office of Coast Survey). Updated weekly. Official Coast Pilot ↗

Local Knowledge

Watch out
Lawson Rock sits in midchannel, a little under half a mile north of Fauntleroy Point. It's lit, but give it a wide berth — it's the one real obstruction in an otherwise open pass.
Watch out
When the wind blows from the south against an ebb current, heavy rips build up off the east entrance near Fauntleroy Point. Currents through this stretch of Rosario Strait can run 3 to 7 knots.
Tip
Washington State Ferries run through here constantly on the Anacortes run. Keep a sharp lookout and stay out of their way — they don't have much room to maneuver inside the pass.

Plan a Trip Through Thatcher Pass

1. Start from

Nearest harbor on each side of the narrows. Pick a side to start there.

2. Cross to the other side of Thatcher Pass

Cap Sante Marina (Anacortes) → Thatcher Pass · 11.0 nm · ~1h 23m at · from the east

Questions

What is Thatcher Pass?: Thatcher Pass runs between Blakely Island and Decatur Island and is the main ferry route between Anacortes and the San Juan Islands. It's about half a mile wide at its narrowest, and the water is deep and mostly clear of hazards.
What should I watch out for at Thatcher Pass?: Lawson Rock sits in midchannel, a little under half a mile north of Fauntleroy Point. It's lit, but give it a wide berth — it's the one real obstruction in an otherwise open pass.
What does Class 2 mean?: Class 2 is BoatRoutes' own 1-to-5 rating of how costly a timing or judgment mistake is here — it is not a NOAA scale. Class 2 means one thing to plan around (depth, a schedule, or mild current); getting it wrong costs time, not safety.

Predictions, not observations · U.S. Coast Pilot 10 (7 ed.)

U.S. Coast Pilot text is a work of the U.S. Government and is in the public domain. Per 17 U.S.C. §403, no copyright is claimed in that text. BoatRoutes is not endorsed by NOAA.