One of the most perplexing aspects of sailing in atolls is using buoys to partially lift your anchor chain. In this article, I’ll share the valuable lessons we learned while adopting this unconventional anchoring method.
When we first encountered this technique, it seemed to contradict everything we had learned and practiced about anchoring. Conventional wisdom dictates that an anchor chain’s angle should be as low as possible, nearly parallel to the seabed, allowing modern yacht anchors to dig firmly into the ground. The idea of lifting the chain with buoys, thereby worsening the angle of pull, felt entirely counterintuitive. We couldn’t help but wonder: Could this method really work? And if so, why?
As with many aspects of sailing, the answer lies in finding the best compromise among conflicting requirements.
The atoll environment
Atolls, like Raroia where we anchored recently, offer excellent protection against ocean swells thanks to their surrounding outer reef. However, the lagoon itself presents a unique challenge: it’s dotted with coral heads, often called “bommies.” These large formations extend from the lagoon floor, which can be over 30 meters deep in places, to just below the water surface. This makes navigation from the pass to the anchorage a tricky endeavor.
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- Bommies appear like spots on a Dalmatian when viewed using satellite imagery.
In satellite images, bommies appear as bright spots in the dark blue water of the deeper lagoon. Conversely, in shallower anchorage areas, they show up as dark spots against the light sandy bottom—creating what we jokingly call a “Dalmatian” effect.
The challenges of bommies
Even if bommies were simply rocky formations, they would pose a risk to anchoring. The anchor chain could get caught or wrapped around them as the boat swings, potentially damaging the ship’s fittings or hindering a quick anchor-raising maneuver. However, bommies are more than just obstacles—they’re living coral formations, vital habitats for reef fish, and entire underwater ecosystems in their own right.
These coral heads are extremely vulnerable and slow-growing. An anchor chain dragging across them can cause immense, long-lasting damage. This environmental concern is a crucial factor in adopting the “floating” anchor chain technique.
The floating anchor chain technique
Keeping it short but sweet here’s how the method works, starting with the equipment before going into the process itself.
Buoy selection
While fenders can be used to float your anchor chain, they’re subject to considerable stress from constant water pressure. Pearl farm buoys are a preferable option and are often available cheaply or can be found washed up on outer reefs. Attach a short line with a high-quality snap hook to each buoy for easy attachment to the chain.
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- Pearl farm buoys are a good option
The anchoring process
Once you have your buoys, you want to follow these general steps to set out the anchor chain.
- Find a large, sandy patch free of dark spots (visible bommies).
- Lower the anchor and let out a chain length at least twice the water depth before attaching the first buoy.
- Place additional buoys at intervals of 5 to 10 meters, depending on buoyancy. A good rule of thumb is to space them at intervals equal to the water depth.
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- For example: In 7.5 meters of water with 40 meters of chain, we attached the first buoy after 17 meters, then two more at 7.5-meter intervals.
The effectiveness of the technique
While it might seem that lifting the chain would reduce the anchor’s holding power, this is not significantly affected in lighter winds. However, in strong winds (around 30 knots) or when the anchor is forcefully pulled, the chain forms an almost straight line between the anchor and the bow fitting, regardless of the buoys.
Additional considerations
When cruising in areas where floating the anchor chain makes sense there are a couple of things to keep in mind.
In calm conditions the floats may move and cluster near the boat’s bow. You’ll want to ensure the chain between floats can’t tangle with bommies by keeping the maximum chain length between each one no more than twice the depth over bommies.
When navigating anchored areas, it’s a good practice to maintain a greater distance from other boats’ bows. This is because submerged floats may not be easily visible as you move through the anchorage.
By adopting this technique, we can anchor safely in these beautiful but challenging environments while minimizing damage to crucial coral ecosystems.
Have you tried floating your anchor chain? Share your tips down in the comments.
By Ralf Gerking
Ralf and Wiebke have been cruising full time aboard their Hallberg-Rassy 43 Flora since 2019. Starting in Greece, they crossed the Atlantic via Cape Verde, and sailed the Caribbean and the US East Coast from Maine to Florida for two seasons. They then sailed south through Central America and, after transiting the Panama Canal, took Flora on a Northern Pacific loop via Galapagos and Hawai’i to Alaska and British Columbia, and back to southern Mexico. They are now in the Pacific again, this time taking a more conventional westerly route.
A good article, thanks.
Great summary article on floating the chain. Our chain is very heavy so we can only put 10-12 feet between the floats, otherwise the chain sits on the sand floor!
Super helpful as we get ready to be in anchorages like this.
Great info, thanks! If you want to dive deeper into the physics and find out why the floats don’t effect the holding a lot, here’s a talk I gave a while ago in Mexico: https://youtu.be/P0nPdWUP4Po?si=ku7lyQio4zkzSlex
When we had 5/16 chain we needed to put the 15kg pearl floats every 20 feet to keep the chain clear of bommies. A great place to find pearl floats is the first atoll one gets to from the Marquesas. The atoll of Raroia. There are hundreds of floats in a pile from a no longer working pearl farm. The caretaker will hook you up if you bring some goods for trade. We found that we used 3-4 floats in the year we were in French Polynesia. The pearl farm is marked on the No Foreign Land map for the atoll of Roroia in the Tuamotus. Floating chain does nothing to hamper the effectiveness of your ground tackle. The scope is still the same when pressure from wind our motor is applied. We sat out winds in the 50+ knot range in an atoll with pearl floats and we did not budge. Use one meter pendants hooked to the floats with easy cheap carabineers or quick clips of some sort that fit into your anchor chain link. It makes for quick deployment and recovery. We stage the floats on the lifeline hanging overboard so we can clip them on as the chain is deployed. This helps when it’s blowing good out and you need scope quick in a tight area. Remove them in reverse for hulling anchor. Just clip them onto the outer life line as you are recovering the chain. Then you can Stowe them after the anchor is up and you are free of bommies. We tried using fenders before we found our pearl floats and they just sank as the water pressure was to great and the air squeezed out. Once you get it down it’s easy. We have seen boats get wrapped around bommies and end up short scoped. This usually leads to cracked deck parts and is horrible to witness. Do not think you can get away with no floats in these areas. Usually someone like me has to dive down and dangerously try to get you untangled. I take payment in beer or rum. Thanks for this great article. Tom does a great presentation of this as well. They have spent many months/years in these anchorages.
I have no experience with “bommies”, but came to thing … could it be an idea to use (yellow) floating rope rather than chain between the anchor and the boat under such circumstances?
Other thoughts:
* In real bad conditions there will be no catenary effect of the chain as it will be bar tight, and one may be better off with rope than chain anyway as the rope gives better elasticity.
* Even in areas without “bommies” there may be an advantage in not having a long heavy chain on the sea bottom, as it may get entangled in junk, old moorings and rocks, and destroy sea weed and other ecosystems. (I’ve more than once experienced chain getting entangled with junk as the boat rotated around the anchor).
* A floating anchor rope causes a big risk when other boats navigate through an anchorage, but not that much worse than floating chains! The rope should at least be yellow, and perhaps at least one bouy attached to it just for the signal effect.
* If a rope gets entangled on sharp rocks (or a “bommie”?) it may get chaffed and snap – so it’s very important to make sure there is only sand around the anchor. Or perhaps have some few metres of chain between the anchor and the rope.
When my chain got rusty some few years ago and the windlass also stopped working, I replaced the chain with a rope as a “temporary measure”. It did last for some few years, and I discovered there are many advantages having a rope rather than a chain – but the chaffing problem can be very dangerous. I did have an incident with this, nearly lost my boat. I’m now utilizing 20 meters of chain combined with 32 meters of rope which may easily be extended if needed. Even without the problem with “bommies”, I have considered to connect a small floater near the rope/chain interface to try to ensure the rope won’t be dragged along the bottom.
Rope and coral (bommies) aren’t a good combination in my opinion.
So excited to see SV Tieton’s fenders in one of your photos! Our anchor chain wrapped around our keel in Huahine’s shallow anchorage that has a lot of cross current changes. In the future, we’ll also float our chain in that situation.
Thanks for C.A.R.E. ing. Code of Anchoring in Reef Environments. Yacht anchors and chains have destroyed many coral reefs throughout the tropics. Share the care, https://youtu.be/CQYRP–syag?si=f-cxCCM94JCl35h6
Thank you for sharing this well written article, Ralf. We have been sailing in the Tuamotus for a few months now and we highly recommend to get the clips to attach the buoys to the chain more quickly.
We have the first 2 buoys on 2 metre ropes and the second 2 on 1 metre ropes. Sometimes we have found that we need a bit shorter scope (not always double the depth) before attaching the first buoy as it can be hard to find a sandy patch big enough to swing 360° without catching the chain. We have a Rocna 33kg anchor so it digs in really well.
I agree that the bommies are mini ecosystems and need protecting from our chains, ropes and anchors. Floating your chain makes a huge difference.