A Coral Challenge

Voyaging in the Pacific involves considerable blue-water work, sailing in the deep ocean between the vast number of islands. But it also inevitably means dealing with large fringing coral reefs and fields of coral heads. In a transit of New Caledonian waters, we recently found ourselves having to pick our way through coral. Here are a few tricks for getting through coral areas unscathed.

Our chart of this area read, “incompletely surveyed, numerous coral heads.” The area so marked was about 25 square miles and lay directly across our intended route up the west coast of the Île des Pins in New Caledonia. We could take the long 20-mile detour around the outside of it, but that would also mean a long beat back upwind to our Baie de Gadji destination. There were no buoys or channel markers, nor even channels that we could pick from the chart, but the rumor was that others had got through, and we had a hand-sketched “chart.” Our GPS would be of little use as we did not know exactly where the hazards were in order to avoid them.

The west coast of the Île des Pins, often known as the Jewel of the Pacific, is a mass of reefs and coral heads. A few days before we had made the 40-mile trip south from Baie de Prony at the southern end of Grand Terre. Apart from a few well-marked reefs, our route took us well outside the unsurveyed areas. This was just as well since the weather was mostly overcast, it rained, and the sea was glassy smooth, the very worst conditions for messing about among the reefs.

Today, thankfully, was very different. Conditions were ideal: bright sunshine and a light breeze, a rising tide, and four experienced gunkholers aboard. As it was not my boat, I got the aloft look-out role. “Mad dogs and Englishmen go out in the midday sun,” runs the popular Noel Coward lyric, to which he could have added “reef navigators.”

After leaving Baie de Kuto there was quite a swell as we rounded the southwestern tip of the island, which did not augur well for my lengthy spell up the rigging, but at least we would soon be in the lee of the reef and island. The sketched “chart” gave a route related to a bearing on a point halfway up the west coast. But it was soon obvious that, from at least five miles away, picking with any certainty which part of the low featureless coast was “the point” was impossible. The 15-knot breeze over the starboard quarter made any obstructions ahead a lee shore. We knew that any current would be unpredictable, but rather than wait for the tide to rise a little (a three-foot-plus range was expected), we decided on having the full range available. We would then still have the last of the rising tide for the shallow section entering Baie de Gadji at the end of the trip.

So, with the swell now calmed behind the main reef, up the rigging I went, well protected from the tropical sun with sunscreen, harness, hat, and long-sleeved shirt, and kitted out with a good set of polarized sunglasses. Most aloft perches are not designed for the lengthy spell I had in mind, so I put on a good pair of deck shoes. The mast was equipped with steps to the top, but the first set of spreaders was good enough.

With no clear idea of the “point” from which to set the suggested bearing, it was a case of following what seemed most likely. There appeared to be three options: an inshore route (which looked decidedly shallow a little farther along) or two outer passages, both wide guts of deep blue, at least from the mast. Taking the middle option we set off, motoring cautiously. A few doglegs were needed to pass the occasional coral head that protruded into the channel and a couple of smaller isolated ones were avoided in the same way. The inshore route was now looking to be impossibly shallow, but we decided to press on. It was eyeball navigation or nothing, but in these conditions it looked straightforward enough.

The deck crew called out the depth from time to time so that I could calibrate the visual appearance of the bottom to actual depth. From my elevated perch I could clearly see some distant islands, but a fix would only be of academic interest at this stage since it would prove only that we were, as we well knew, in the middle of a large reef-strewn area. We certainly could not work out a route from the fix to safety; retracing our route was the only way out at present. The easy route into the maze was encouraging, but I pondered the responsibility of the man aloft in conning another’s boat. It seemed better that the skipper was in charge of boat handling below while I continued aloft. That left final decisions to the man at the wheel. It was soon apparent that the blue would run into some very shallow sections shown as much lighter blue and almost white with tinges of brown.

By way of relief from the mounting tension, a turtle, fine off the port bow, provided a timely interruption, but it was long gone by the time we got near enough for the deck crew to get a good look. The downside of our situation was that at least if things looked impossible, we could slow right down and, if we did hit, the rising tide would probably get us off again, although the following wind may have added something of a complication. Had we only had the option to sail, some different considerations would inevitably arise. With only a headsail up much of the lookout view is obstructed unless a meandering path is chosen. With just the mainsail there would have been some difficulty in finding a comfortable perch on and around the mast.A turn along the coast

I was grateful for the sun protection – it was hot up there – but at least there were no clouds, so that we were guaranteed good visibility for the foreseeable future without confusing cloud shadows. There was no easy route and a much more regular call out of the depth was necessary to check depth calibration. We reached the point where a more or less direct course was impossible. The outer deep channel, running parallel, also went nowhere, so perhaps the others had used the shallow inner route after all. All we had to do now was to cross over to it.

Going back inshore to find deeper water seemed intuitively wrong, so it was with supreme caution that we turned 90° and headed east. Still, no way looked clear, and now, broadside to the coast, it was clear that the current was setting us north. An adjustment was made so that we were now headed direct into the southeasterly, which had strengthened – just as well, since we were motoring. Tacking through here would have been a nightmare, especially for me aloft. I had settled for a sitting position on the first cross trees with the occasional foray to the second spreaders in the hope of the situation becoming clearer. No such luck – even if we got into the inner channel area there was still no obvious route from there northward. Perhaps the whole way was blocked?

With depths now regularly down to just more than three feet we were reduced to a crawl. We gradually crabbed our way across to what seemed slightly deeper water, judging from the darker hue, but the expected increased depth did not materialize. The complicating factor appeared to be weeds or more likely sea grass on the bottom, which made the water appear darker and therefore deeper than it was.

Now we were faced with a new dilemma. Which was deeper, the darker grassy patches or the light, turquoise-colored weedless areas that already looked pretty shallow, and shallower still against the darker surroundings? It did not help the anxiety quotient that the shallower the water, the higher pitched became the voice on deck calling the depths. Unable to be confident of my observations, I thought it prudent to suggest a stop to regroup, but those on deck appeared more confident. We zigged and we zagged, but for all the difference that became apparent from the depth sounder, we just seemed to be avoiding thicker patches of grass.

It was very unsettling from aloft. No doubt it would have been clearer from the perspective of a snorkeler, which was one of the options we could have adopted. But as we were still crawling – oh so slowly – the worst that could happen was a bit of keel sanding since the coral heads were very infrequent in this depth. Even so we were no doubt going much faster than a swimmer, especially with a bit of following current. We were at the previously elusive point now, which should have meant the end of our concerns, but, although I could see the deep blue farther to north, and tantalizingly close, there was a large patch of reef which we still had to avoid.

A very light turquoise dogleg route lay to the west, and a darker weed bank to the east between the reef and the shore. The grass area was the direct route so, feeling a little easier, we kept to the direct route. Again the depth began to shallow as we approached what appeared to be a grassy sand bar and the current appeared to be taking us fast onto it. My instincts were again to call for a stop, but this fell on deaf ears. I held on tight, expecting a jarring thud and to be thrown off my perch at any moment, but it did not come, and after skirting the northeast of the clearly visible brown reef, we headed straight for the deep blue and were much relieved. We relaxed for a relatively easy couple hours’ sail.A great blue bath

Trying to make sense of it all on the chart afterwards was still not easy except that this last grassy bar was marked and clearly shown as having enough depth. No wonder the deck crew had been so confident; they might have mentioned it to me. Baie de Gadji is a shallow, 12-foot sandy-bottomed lagoon totally enclosed by a number of surrounding islands and associated reefs which we still had to negotiate. One shallow entrance passed along the windward side of Moneoro Island, but, somewhat shaken by the difficulties previously encountered, we opted for the alternative approach from leeward away from the choppy sea that the 20-knot-plus afternoon breeze had created. The sun, although still high, was in the west and would be behind us on this approach, although a number of clouds were now scudding overhead.

As we passed well to leeward the isolated reefs were easy to see. The chart showed a passage with a bearing to a beach. We nearly made the easy mistake of heading for the wrong beach, but by checking the approach bearing against the chart we realized this was a false entrance. To add a further complication, a lonely black cloud deluged us with a short, sharp shower, during which we stopped and drifted away from the dangers until we could see well enough to press ahead. A little farther on we found the correct entrance, which was certainly narrow enough with waves breaking over the reef on both sides. Some course adjustments were needed to negotiate a few coral heads in the pass.

Our goal, the “great blue bath,” was now only 400 yards away, but the very shallowest part was still to come. A bar between the last two islands was in our way. As the depth dropped to 8.25 feet again, we were in weed. Wary of pushing our luck, and with three hours of tide in hand, we retreated to anchor for a well-earned late lunch. We had hit anything, but there were times when we came awfully close.

A couple of hours later we made the last 400 yards of the trip. Again, the exact depths were very confused by weed and/or sea grass. We moved very slowly and scraped the keel at one point. But at last we were in Gadji. We dropped the anchor and dove into the warm, 20-acre “bath.” Getting out again we would leave for another day. n

Kim Taylor is a writer and photographer. A native of New Zealand, he lives in Keri Keri.

By Ocean Navigator