Anchoring as the wind rises

Boat handling · Power & sail

An anchor that held in the afternoon calm may not hold in a night blow. Anchor with enough scope for the wind you expect, confirm the anchor is set, watch for dragging, and decide early whether to add scope, re-anchor or leave.

Scope

• Scope is the length of rode let out compared with the height of your bow above the bottom: water depth plus the height of the bow chock, allowing for any rise of tide while you are there.
• Sources give different figures. BoatUS recommends 7:1, or 5:1 for a small boat with a light anchor in good weather. An experienced cruising author uses 4:1 to 5:1 with all chain and 6:1 to 7:1 with nylon. The USCG handbook gives an angle instead: the rode should meet the bottom at 8 degrees or less.
• The angle matters because holding falls as the pull starts to lift the anchor. Practical Sailor's tests found holding for most anchors drops off sharply once the lead angle passes about 8 degrees.
• As the wind rises, let out more rode if you have room; BoatUS also suggests setting a second anchor. Check swinging room: the boat can swing all the way round with wind and tide, and boats on different rodes swing differently.

Is it holding?

• Set the anchor by backing slowly while paying out, then holding the rode so the anchor bites. Then take bearings on two landmarks at least 45 degrees apart, or use radar ranges. If the bearings change while your heading stays the same, you are dragging.
• A rode that alternately jerks tight and goes slack, or vibrates, usually means the anchor is dragging or bouncing over hard bottom.
• GPS anchor alarms help, but set the alarm circle over the spot where the anchor went down, not where the boat came to rest, and don't let them replace looking.
• Keep an anchor watch when things are changing: the weather, whether you are holding, other boats dragging or anchoring near you, and the rode's connection and chafe.

Re-anchoring or leaving

• If the anchor drags, try paying out another 10 to 15 feet and snubbing again. If that fails and room is tight, recover it, check the flukes are not fouled with mud or weed, and start again.
• Plan your way out before dark: keep your inbound track on the plotter, or lay a route out while it is calm, so you can leave safely at night if you must.
• If a forecast wind shift would turn the anchorage into a lee shore, consider moving before it arrives.
• Put chafe gear on the rode where it passes through the chock.

General guidance for recreational boaters, researched from the sources listed and written in our own words. Your equipment manuals, local knowledge, the Navigation Rules and a qualified instructor come first.