Quick Tip: Anchoring Among Coral

Anchoring among coral can put both your anchor chain and the coral at risk of being destroyed. Try this technique to keep your chain in one piece.

anchoring in coral
Anchoring in coral can put both the coral and your anchor chain at risk of being destroyed.Tim Barker

Imagine your boat entering the calm, turquoise water of a lagoon. Outside, the swells you just sailed through explode on the fringing coral reef. In this cruising paradise — typical in the tropical Pacific and Indian oceans — the water is so clear that at 20, 40 and even 60 feet deep, the bottom holds no secrets. At the anchorage, this transparency reveals a mostly white-sand bottom interrupted by stand-alone coral structures, called bommies, that rise like cactuses from a desert floor.

Yikes! Ranging in size from a basketball to a minivan, these bommies can abrade the galvanizing of your chain. They can foul your anchor. After just a bit of swinging, your rode can wrap bommies until your scope is effectively reduced to 1-to-1 (which can then pit extreme forces against your snubber and deck hardware in the event of storm-induced swell). Yet despite these threats, when anchored cruising boats and bommies tango, it’s most often the bommies that endure the most damage.

Even when merely brushed across coral, anchor chain causes damage that is either irreparable or very slow to heal. Bommies often grow up and out from a narrow base of rocklike exoskeleton. Juvenile bommies can be broken and toppled fairly easily by an anchor chain drawn tight across them.

Fortunately, there is a time-tested anchoring technique that greatly reduces the chances of snagging a fragile bommie. It’s a technique we learned and became skilled at in the atolls of French Polynesia and the Cook Islands.

After locating the largest clear patch of sand we could, we’d attach a fender to our chain (by tying a hitch) every 25 feet as we deployed the anchor. (Our chain is 3⁄8-inch diameter, and we use Polyform F5 and G5 fenders.) The effect is that our rode hangs suspended above the tops of the bommies, preventing damage to our chain, our boat and these slow-growing organisms.

–Michael Robertson