In the latest Bluewater Sailing Techniques video, our experts explain how to anchor safely in coral waters

Anchoring in coral is illegal in many places and should certainly be avoided if possible. A nice patch of sand is better for holding, better for your ground tackle and better for the environment. However, there are places and anchorages where you simply don’t have an option – and believe me you wish you did!

I am not talking about anchoring in the middle of a pristine reef, but many South Pacific coral atolls are strewn with small coral heads in the anchorage, so even if you manage to land your anchor in a nice sandy patch, the chances are you may get your chain wrapped around one or many, and if the wind is changeable you can tie the chain in all sorts of knots.

These coral heads usually stick up around a metre from the seabed and it can be difficult to distinguish the height. This is further complicated because many of the anchorages are deep and so it’s hard to see what is going on.

There are several problems with this. Coral is hard and can seriously chafe your anchor rode – a rope stands no chance and even chain can take a beating, all the while making a graunching noise which can be felt through your snubber and resonate through the boat to ruin your night’s sleep.

With every wrap or snag you effectively shorten your scope, and therefore the catenary effect, or spring, in the chain is diminished. This is what usually absorbs the load when a gust hits the boat or you’re anchored in a swell – as the yacht pulls back or the bow rises, the weight of the chain lifting off the seabed takes the brunt and prevents any snatch loading.

The problem with coral snags is that the chain can get so caught and wrapped that the pull becomes straight down. A firmly wrapped chain is very secure and unyeilding, but a gust or swell can apply too much shock loading, which can cause real damage and, since the coral is strong, the damage is to the boat. Depending on your ‘weak link’, you can snap the snubber or the chain, rip out a cleat or bow roller or, worse, the windlass!

Getting the anchor up can be a real challenge. We have been in anchorages in the Tuamotus and watched (and helped) yachts for up to two hours trying to raise their anchor. In some cases where the water is shallow or clear enough a look below with the snorkel can map out your chain’s path and help the helmsman unwind the chain. Otherwise keep someone in the water to watch and guide you or if it’s really stuck and unclear, a dive may be required to free it off.

In the tradewind areas, the times the wind is likely to be really shifty is either when it’s very light airs (when it’s less of a problem) or when a bigger system is approaching. Despite being in a protected lagoon, if the wind blows the wrong way there can be quite a chop.

So, how can you remain secure at anchor yet still protect coral heads, avoid any snagging and ensure your anchor is free to weigh again quickly if needed? We show you how in this video.