Anchoring in Pacific Northwest Waters

Peter the Great Bay, August 1978

I anchored a six-oar yal off an uninhabited island in Peter the Great Bay one summer evening, stern-tied her to a tree on the shore, and set up a tent on the beach with my crew. The wind was a steady offshore. I was the youngest aboard but the most experienced, and I had decided on the anchorage. Some time during the night the wind shifted, rolled around through the south, and pushed us square onto the rocks. The boat was washed up before the tide and the wind together let go of her. None of us was hurt. The yal was repaired. She was never the same boat again.

I think about that anchor decision often. Forty-something years later — through Strait of Georgia crossings, San Juans summers, and Princess Louisa overnights — I have not made another anchoring mistake of that magnitude. But the rule that came out of that night is the rule I still anchor by:

The wind that holds you off the rocks at sundown is not the wind that will hold you off them at 0300.

Pacific Northwest anchoring is governed by that fact and a few others. This article walks through the technical work — choosing the spot, calculating scope, selecting the anchor, setting it, verifying the set — and the specific PNW additions: twelve-foot tides, four-knot currents in the passes, kelp and eelgrass on most shorelines, williwaws in the fjords.

Choosing the spot

Three questions, in this order.

Is the bottom good? Mud and clay hold an anchor like a vault. Sand holds with the right anchor and enough scope. Gravel and broken shell hold marginally. Rock holds only if the anchor catches in a crevice — most anchors do not. Eelgrass holds nothing. Kelp holds nothing. Most of the soft-mud bottoms in Puget Sound and the Salish Sea are excellent holding; most of the rocky shorelines are marginal at best.

Bottom type is shown on NOAA chart 18421 (and most digital chart plotters) with standard symbols: small dots for sand, hatched pattern for mud, r for rock, Wd for weed/eelgrass, Sh for shell. Read the bottom before the anchorage.

Is the swing room sufficient? The boat will swing through 360° as wind and current change. The swing radius is the scope plus the length of the boat. In a 14-foot tidal range at 7:1 scope, a 35-foot sloop in 25 feet of water swings on a 200-foot radius — a 400-foot circle. If there are other boats in the anchorage, their circles overlap yours, and the math has to allow for everyone’s swing at the worst moment, not the best.

Is the wind protection good across every quadrant? The afternoon’s prevailing wind is not the morning’s. Frontal passages reverse wind direction in PNW summers; thermal effects build on lee shores after sunset. The question is not does this anchorage protect against the current wind — it is does this anchorage protect against any wind I might see in the next twelve hours. If the answer is no for a quadrant, the answer is no.

The 1978 yal did not break loose because of bad anchoring. The anchor held. She broke loose because the wind came round and pushed her square against the rocks that had been at her stern. Stern-tied to a tree did not save her. A different anchorage would have. Do not anchor on a lee shore at any wind speed under any conditions. The lee-shore rule is the most important rule in cruising anchoring, and it is the one most often broken.

Scope

The fundamental anchoring relationship, stated honestly:

An anchor only holds if the rode pulls horizontally on the anchor head. The horizontal angle is what drives the flukes deeper. A vertical pull — the boat lifting straight up on the rode — pulls the anchor out. Scope is the ratio of rode-out to depth-of-water. Longer scope keeps the rode more horizontal at the anchor.

PNW scope ratios:

Calculate scope on the high tide depth, not the depth at the time you anchor. A 12-foot tidal range is normal in Puget Sound; some passes run 15. Anchoring in 25 feet at low tide means 37–40 feet at high. 7:1 scope on the higher number is 280 feet of rode. If your rode is 200 feet, your scope at high tide is 5:1 — at the bottom of the working range and not enough margin for a wind shift.

Most cruising boats carry 200–300 feet of chain, or chain-plus-rope rode. That practical limit puts useful PNW anchorages between 10 and 40 feet of water at low tide. Beyond that depth, a state-park mooring buoy or a marina becomes the better answer.

Anchor types

Anchor design has improved dramatically since the 1970s. The new generation — Mantus M1, Rocna, Spade, Ultra — sets faster and holds harder than the older designs (CQR plough, Danforth, Bruce claw) on the same bottom. If you are buying a new anchor for a PNW cruising boat, consider a new-generation design.

Working notes by type:

New generation (Mantus, Rocna, Spade, Ultra) — fast set in any bottom that holds at all. Excellent in mud (PNW default). Acceptable in sand. Reset reliably when the boat shifts on a tide change. The standard recommendation for PNW cruising boats from 30 to 50 feet.

Plough / CQR — the historical workhorse. Fine in mud and sand. Slow to set; can plough the bottom rather than digging in. Many older PNW cruising boats still carry one as primary. Serviceable but obsolete.

Danforth / fluke — extremely good in mud and sand for its weight. Useless in rock or weed. Excellent backup or stern anchor; not recommended as primary in mixed-bottom areas.

Claw / Bruce — the all-rounder. Good across most bottoms, not the strongest in any. Many older fleet boats run a 33lb or 44lb claw and have been satisfied with it.

Fisherman’s — only for rock bottoms. Used in Maine and the Atlantic provinces; uncommon in PNW.

Anchor weight depends on boat displacement, not just length. A 38-foot cruising sloop displacing 18,000 lb needs a 35–45 lb new-generation anchor or a 45–55 lb older-generation one. Match anchor and rode to the manufacturer’s recommendation for the boat, not to the cheapest option in the chandlery.

Setting the anchor

Five steps. Drilled, this takes three minutes.

One. Approach the spot bow-first into the wind or current, whichever is stronger. Stop directly over the spot.

Two. Lower the anchor — do not throw it. Let it descend to the bottom on a slack rode. Throwing produces tangles, shock-loads the rode at the cleat, and means the anchor often lands on its side rather than upright.

Three. Pay out rode steadily as the boat drifts back from the anchor. Aim for a 2:1 ratio at first — twice the depth of water in rode out. Set the rode briefly on a cleat or windlass to feel for resistance: the anchor either bites and the boat decelerates, or it skips along the bottom. If it skipped, retrieve and try again two boat-lengths upwind.

Four. Once the anchor has bitten, pay out to your target scope. Make the rode fast at the cleat. If using all-chain rode, use a snubber line to take shock loads off the windlass.

Five. Set the anchor under power. With the engine in reverse at moderate throttle (1500 rpm or so) for thirty seconds, watch a bearing onshore — a tree, a chimney, a charted feature. If the bearing holds, the anchor is set. If it walks, the anchor is dragging, and you start over.

Verifying the set

Bearings are the standard. Take two: one perpendicular to your line of swing, one across the bow. Note them. Check them after fifteen minutes. Check again at the tide change. If they walk, the anchor is dragging.

Modern chartplotters carry an anchor-watch alarm. Set the alarm radius slightly larger than your scope (e.g. 250 feet for a 200-foot scope) so a tide-change swing does not trigger it but a real drag does. The alarm is a backup, not a replacement, for the bearings. GPS jitter at typical chartplotter accuracy (±10–30 feet) means a tight alarm radius produces false positives that train the crew to ignore alarms.

For overnight anchoring, the cruiser’s first wake-up at the tide change is non-negotiable. If you slept through the 0230 tide reversal, you slept through the moment your anchor was being asked the hardest question of the night.

Specific PNW conditions

Twelve-foot tides. Calculate scope at the deepest predicted depth on the night you are there. NOAA tide predictions for Puget Sound stations are accurate to within minutes and inches; use them.

Strong currents in the passes. Cattle Pass, Deception Pass, Active Pass, Yuculta Rapids, Seymour Narrows — these run at 4 to 16 knots peak. Do not anchor in them. Period. Anchorages near them — Reid Harbor for Yuculta, Penn Cove for Deception — should be approached and left at slack water, not at peak flow.

Kelp and eelgrass on the shorelines. Most rocky and shallow PNW shores carry kelp through summer. Kelp wraps the anchor and the rode; the anchor does not bite the bottom. Eelgrass is worse — it does not wrap, it just refuses to hold. Both are visible from the foredeck on approach. If you see kelp where you intend to drop, move.

Williwaws in the fjords. Hood Canal, Princess Louisa, the Desolation Sound mainland inlets — air drops down the surrounding mountains in cool nights and accelerates over the water as a katabatic gust. Williwaws can hit forty knots in two minutes. They have ended otherwise excellent anchor sets. The defence is heavier scope and a willingness to relocate before nightfall if the weather looks unsettled.

When the anchor drags

It will, eventually. Steps:

1. Engine on. Crew on deck.
2. Determine direction of drag — bearings or chartplotter.
3. If you have room, deploy more scope. More scope is the cure for most drag.
4. If more scope is not enough, weigh anchor and reset. Choose a different spot, ideally upwind, ideally on visibly better holding.
5. In a crowded anchorage, alert the boats around you before maneuvering. Use VHF 16 or a hailer. A boat dragging at 0300 is everyone’s problem.

If the anchor will not break free in the morning, try reversing direction from the original set. A buoy on the rode and a slow circle around the spot often pops it out. If not, motor close to vertical over the anchor and try again. The standard last resort is to dive on it. The unstandard last resort is to cut the rode and mark the spot with a buoy for later recovery.

A word on stern-tying

The 1978 yal was stern-tied to a tree onshore. It did not save her. Stern-tying — common in BC fjords and a few PNW state-park anchorages — has its uses: it keeps the boat from swinging in tight anchorages, and it pins the bow at a useful angle. It does not protect against a wind shift. If the wind comes around to the stern, the boat is held against rather than away from the rocks. The fact that there is a line to the shore is the problem, not the solution.

Stern-tie only when the wind protection on all four quadrants is genuinely good and the holding under the bow is excellent. Treat the stern line as cosmetic security, not real security.

The rule that came out of August 1978

The wind that holds you off the rocks at sundown is not the wind that will hold you off them at 0300. The anchorage that looks fine at high tide may not be the same anchorage at low tide; the anchorage that has fifteen boats in it at sunset may be three boats in it at midnight, and the swing math will have changed. Anchoring is a discipline of the worst case, not the average one.

Choose the anchorage on the worst weather you will see. Set the anchor like you mean it. Verify with bearings, not with the chartplotter alarm. Wake up at the tide change. The boat that drags at 0300 in twenty-five knots is the boat that was never set in the first place.

Related: Tides and Currents in Puget Sound · Reading Nautical Charts · Best Puget Sound Anchorages