This is an odd subject. In a previous Blue View, I talked about reefing the sails and how we do it aboard Nine of Cups. That made my mind wander a bit and I thought about the other definition of a reef – those hard spots we've had close encounters with from time to time. From that, my thoughts moved on to some of the magnificent South Pacific coral atolls we visited. And then I recalled the rather unusual anchoring technique we used in those atolls. While we were in Patagonia, we spent a pleasant evening with a French sailor we met there. He was going on to Tierra del Fuego, where we had just been, and we were headed out across the Pacific, where he had just arrived from. These chance meetings are always a great opportunity to go over each others' charts and share information over a glass of wine. We shared with him the unusual anchoring techniques used in the deep, tight anchorages of southern Chile, and he shared with us his anchoring technique for the Pacific atolls that are typically strewn with coral heads, also known as “bommies”.
An atoll is usually a ring-shaped coral reef surrounding a lagoon. Sometimes the reef is high enough to form a number of islands. Often there is a passage into the lagoon that is large enough to sail through and into the protected waters inside. Getting through one of these passages is often good for an adrenaline rush as they are subject to strong currents, large standing waves and the occasional coral head. Once inside, the waters are calm and pristine, and every bit what you imagine a South Pacific paradise would be like. The lagoons are, however, usually dotted with coral heads that are rarely charted, so navigating and anchoring amongst them can be a challenge.
To anchor, you look for a sandy spot clear of coral heads. You make sure there are no coral heads within the area that the boat will swing that are close enough to the surface to be a threat, and drop the hook. You then let out adequate chain and set the anchor by backing up until you are sure it is well dug in. A prudent sailor will probably attach an anchor snubber, and keep an eye on things for awhile to make sure the swinging room is adequate and that the boat is staying put, but the anchoring task is essentially done.
In an atoll, even if there are no coral heads close enough to the surface to hit the boat, there are quite likely a number of them well below the surface. As the wind, tide and current change, your chain will get wrapped around these coral heads. This is bad for a number of reasons.
The first reason is that your chain will damage the coral. If the hundreds or thousands of sailboats that came before you and anchored where you are didn't already kill the coral, you will certainly continue to push it towards its demise. It's also not good on your chain, and if you are using rope rode, the coral will quickly chafe through it.
The second reason is that when it is time to leave, you may need a snorkeler in the water to give directions as you maneuver the boat to unwrap and retrieve the chain. This can take awhile and isn't something you want to worry about if you have to leave in a hurry.
The third reason is that you may wrap so much chain around the bommies that you have no scope left. If there is any wave action at all, the stress on the boat is immense, as there may be no slack at all in the chain.
To prevent this, our friend taught us how to buoy the anchor chain to keep it away from the coral heads. Pearl farming is quite the business in the Pacific, and big plastic floats are used everywhere. These floats are always escaping, and as you voyage through the region, it is not hard to collect a few on deserted beaches. You can also use fenders or empty fuel or water cans.
Start by attaching a 3' (1m) line to each float. I use a bowline, and whip the end to the knot to make sure it can't come loose from the float. Gather these on the foredeck when it is time to anchor. As you let the chain out, after the first 50 feet (15m) or so, start attaching a float every 15 to 30 feet (5-10m). I loop the end of the line through a link in the chain and tie another bowline. Make sure the knot is very tight, then tie a stopper knot in the end to help ensure the bowline doesn't work itself loose. (We have lost an occasional float, so I am open to suggestions on a better knot.) The distance apart will depend on the type of float you are using and the weight of your chain. Some experimentation may be needed to get it just right. Using salvaged pearl farm floats and 3/8” HT chain, I find that spacing them about 20' (6m) apart works well for Cups. When you raise anchor, untie each float as it gets close to your bow roller.
When the wind is light, the chain will float above the coral heads. When the wind picks up, the chain will straighten out much like it would without the floats. I usually let out a bit more chain than normal, just to be safe. We've had some pretty good blows, and, knock on wood, haven't had any issues.
As we were leaving the area, we donated the floats to local fishermen who gratefully accepted them.