Boat Anchoring Tips – How to Match Anchor Size to Your Cruising Sailboat!
Do you carry a Plow, Danforth, Fortress, Delta, CQR, or Bruce anchor on your small cruising boat? Use this sailing tips guide to make sure your metal insurance policy will hold your boat in light wind or howling gale.
Open any marine catalog and you will find marine boat anchors matched to the length of a small cruising boat. But this leaves out several of the important features on your particular boat.
How much freeboard does your boat carry at her bow? The distance from the deck to the waterline–called freeboard–plays a critical role in how your boat behaves at anchor.
Boats with low freeboard tend to lie bow to the wind without a lot of side-to-side motion. Boats with higher freeboard will yaw and hobbyhorse at anchor. Side strain and vertical up and down motion cause enormous loads on your ground tackle.
Sailboats with higher than average displacement (weight), such as the more traditional full keel or modified full keel cruising sailboats, also need beefier ground tackle.
In his classic guide to sailors–“The Seaworthy Offshore Sailboat”–master mariner John Vigor provides a unique method to guide sailors in the best anchor choice, using a plow anchor as a baseline to determine anchor weight.
Use this extract from his table to determine just the right size anchor choices for your cruising sailboat, in particular if you are in the market for a lightweight anchor or storm anchor.
Easy guide to anchor size selection
1. Enter the left column of the table with your boat length.
2. Read the baseline plow anchor size for your boat.
3. Use the calculations beneath the table to find the correct anchor size.
| Baseline Plow Anchor Size Guide for Small Cruising Boats | |
| Cruising Boat Length | Baseline Plow Anchor Weight |
| Less than 22 feet (< 6.4m) | 11 lb. (5kg) |
| 22 – 25 feet (6.7m – 7.5m) | 22 lb. (10kg) |
| 26 – 30 feet (8.0m – 9.0m) | 25 lb. (11kg) |
| 31 – 40 feet (9.4m – 12.0m) | 35 lb. (16kg) |
| 41 – 45 feet (12.0m – 14.0m) | 44 lb. (20kg) |
* Lightweight anchors (Danforth, Fortress)
Choose an anchor 1/2 the weight of the plow.
* Yachtsman or Fisherman type anchors (Luke)
Choose an anchor 2.5 times the weight of the plow.
* Storm Anchors (Plow, Bruce, Delta, or Yachtsman)
Choose an anchor twice as large as those in the table.
* Boats with heavy displacement or higher freeboard
Choose an anchor one size larger.
Example
You sail on a Cape Dory 33, with moderate displacement and average freeboard. You want to purchase a lightweight Danforth anchor. What anchor size should you choose?
Enter the table above and select your baseline plow: 35 pounds. A marine catalog shows these Danforth anchor sizes available: 3.5 lb.; 5.0 lb.; 9.0 lb.; 14.0 lb.; 16.0 lb.; 25.0 lb. Select the 16 pound Danforth, which is the closest size to 1/2 the weight of baseline plow anchor weight shown in the table. For a storm anchor, this boat would need a 70 pound anchor, or 2X her baseline plow weight (35 X 2).
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Use these sailing tips to choose the right marine anchor size for your small cruising sailboat. Make your decision on more than just boat size for confident, worry-free anchoring–wherever in the world you choose to cruise!