We try out a mixture of old-fashioned methods and modern technology to enter an uncharted lagoon

To experience the extraordinary beauty and cultures of the Pacific under sail, you need a few specialist cruising techniques under your belt. We have been sailing in Fiji with Dan and Em Bower on their yacht, Skyelark, to demonstrate some of these and film them for our new sailing techniques series.

This took us to the island of Mana, which has a wonderful lagoon behind coral reefs. Here we entered a narrow coral pass and anchored in an area containing coral heads.

Mana is particularly interesting because it illustrates some of the knottier problems of navigation and pilotage in these areas. Charting in the Pacific is notorious inaccurate. Large areas have been poorly surveyed and never properly updated – I have heard of some atolls in French Polynesia where the charts have been four or more miles out.

Here in Fiji, charts are said to be up to two miles out in some places. At Mana, electronic and paper charts alike don’t show any lagoon at all, as the screen grab below from MaxSea illustrates. But a lagoon does exist, as does a very narrow tide-swept pass through the coral reefs.

A much more exact representation of the island, the pass and the coral reefs was obtained by Dan and Em in the form of Google Earth overlays that have been precisely geo-referenced, as shown below. (More about exactly how this works and how to get this information in one of the next issues of Yachting World.) We used these to establish the pass entrance and its winding course, while using the good old Mk 1 eyeball to con our way in carefully.

With Dan at the spreaders getting an excellent view of the pass from above, and me at the bow, Em worked our way in under engine, slowing motoring ahead against a gentle ebb. Once into the entrance we were committed as it was too narrow to turn around.

Many of the atoll passes in the Pacific are unmarked, or poorly marked – the Tuamotus and the atoll of Suwarrow in the Cook Islands, for example, are completely unmarked. As it happens, the pass at Mana had channel posts, but several of these had fallen down or moved from their intended positions. That highlights why one should never really rely on mark out here.

Once in the lagoon at Mana, we anchored behind the reef. Dan attached small buoys on short lines at every 10m of chain paid out, in order to lift the chain just off the sea bed and avoid it wrapping around any unseen coral heads. While one wants to avoid damaging any coral, heads rising from the bottom can be impossible to identify and avoid if you are anchoring in a deep lagoon and hooking the chain on one can make weighing anchor again really difficult and could damage the windlass.

After a night in Mana we headed on to do some more filming. In the movie Cast Away, Tom Hanks stars as a FedEx employee and postage obsessive who has a plane crash over the Pacific and is washed up on a deserted island. That island is Manuriki, small but dramatic knob of rock in the ocean that trails a golden sand beach like the tail of a comet.

But when we got there the wind had risen sharply and low clouds of drizzle were sweeping across at speed. It was too windy to stay, and even landing briefly would have been sporting, so we turned tail and headed back to Musket Cove. This popular stopover for round the world cruisers seems to be magnetic, in that people venture away and are irresistibly drawn back again. As is the case all over the world it may have something to do not only with a safe anchorage but also with the joys of fresh water, wifi and cold beer.