Guide to a Secure Anchorage
The following five factors add up to a secure anchorage.
1. Seabed.
Your anchor must be able to penetrate the seabed and hold.
Study the chart to choose the best anchor based on the type of bottom.
The best holding ground consists of hard mud or clay.
When in doubt about the seabed quality, use a larger plow or claw anchor.
2. Wind, sea, and groundswell protection.
The ideal anchorage provides
wind and sea protection from at least three sides.
In areas with steady winds, choose a cove protected from the dominant wind direction.
In areas with shifting winds, make sure you will be protected aft er the wind changes direction.
In the Caribbean, many anchorages are exposed to a constant groundswell.
You must use more scope to keep the anchor from breaking out. Make sure you leave an escape path open in case of a wind shift . For instance, with wind out of the northeast, you might choose a two-sided headland to the north. But if the forecast calls for a wind shift to the south, you must understand that the headland could become a dangerous lee shore.
3. Tides and currents.
You need to know the tidal range to compute adequate scope.
Rising tides could break out an anchor with inadequate scope. Lower-than-normal tides could increase scope to the point where the boat swings onto a shoal or into another boat.
In areas with shifting currents, set two anchors. Always be aware of changes in direction and strength of wind, current, waves, and swell when at anchor.
4. Swinging room.
Take the time to circle the anchorage and see if boats are using one or two anchors.
In areas like the Bahamas where currents shift 180 degrees, many boats anchor with two anchors. This cuts down their amount of swing to about one boat length.
In this case, you too would want to follow suit so that your boat swings with the tide in a small radius.
Make sure when your boat swings to a single anchor that it clears other boats and shoals.
If you put out 250 feet of anchor rode, then you should expect to swing in a circle with a 250-foot radius or 500-foot diameter.
Stay clear or upwind of any boat that you suspect has put out inadequate scope.
5. Drag indications and bearings.
After you have set your anchor
and aft er the rode takes strain, check your anchor line for
dragging.
Extend your arm out over the rode and place the back of your hand on the rode.
Any vibration indicates dragging. Pay some line out, cleat it off , and repeat the drag test.
Next, take a drag bearing off the beam.
Look for a natural range—it doesn’t have to be charted. Th e end of a pier in line with a large tree can work.
As long as they stay in line, you aren’t dragging.
In areas without ranges, take a bearing to a single object off the beam.
Record the bearing in your log and check it often.
At night, use lighted objects abeam. Anytime the wind or current causes the boat to swing, select a new range or object abeam.
As a backup, set the GPS or radar alarm to alert you if you start to drag. Use electronics as a backup only, unless you are in low visibility or a remote location without visual landmarks.
If you start to drag, veer (let out) scope right away.
