Common-sense navigation


When I learned to sail in San Diego, the running joke was that every year someone coming home from the Catalina islands would set their autopilot for a waypoint inside the harbor, and then run into Point Loma while they slept. This cruising season has seen more than one notable navigation error, leading to several cruising incidents that serve as sobering reminders that we share the oceans with many other large vessels and with the varying levels of navigation they may practice. We can take these as learning opportunities and look at the ways good sailors use both ancient and modern technology to keep themselves and their vessels safe.

Basic technology
As we approached the southern anchorage of Bora Bora, we realized that all our information was wrong — there is no longer a pier, and the written directions were unclear which side of the buoy to take. From my perch on the bow pulpit, the coral looked way too close through the crystal-clear water. I put my hand over my eyes in despair, waiting for the crunch, while my husband Paul yelled frantically from the tiller, “Take your hand down and point! You need to see!”

No matter what chartplotter, GPS or AIS you’re running, every sailor carries the most important safety technology in their ocular cavities. Many areas of the world are incompletely charted, and in many areas the charts are just a little off. Our electronic charts of the west coast of Mexico were based on 100-year-old charts that are often up to a mile off. This meant that the shape of the land was accurate for planning purposes, but it was all farther east than the charts said. Our computer screen regularly showed us anchored on land. We navigated close to land by sight and by radar, both of which measure what is actually there right now — not what was there 100 years ago, or what we wish was there. Autopilots and chartplotters are like the cruise control on a car; they don’t excuse us from driving.

In the South Pacific, sight navigation becomes even more important, as the discrepancies between chart and reality are more difficult to quantify. As in Mexico, the charts are frequently based on very old surveys, and sometimes even those are incomplete. Sometimes reefs have changed over time, and in a few places new islands are just spurting above the sea. Many passes are marked by ranges, and many lighted markers on the charts do not exist in real life. These challenges do not make this area less beautiful or worthwhile, all you have to do is keep your eyes open.


The top satellite photo of Neiafu shows the extent of the channel, while the bottom image (a vector chart view of the same channel) shows that the charted land features don’t correspond to the satellite image.

Since low coral islands do not show well on radar (and underwater reefs are even more elusive), plan to arrive at a new place in good overhead light. Some yachts use a fishfinder or other underwater sonar, which must be awesome when traveling slowly in winding reefs. We would warn that their small range is not intended to give fair warning when sailing at speed, so it’s still the captain’s job to slow down when near dangers. Many of the yachts that hit reefs in the last year were approaching an island in poor visibility and relied on the chart being perfect. I wouldn’t bet my floating home on it. It’s better to stand off several miles until the morning light.

This can be true even of well-charted places in questionable conditions. We were in Honolulu when the 2015 Transpac race arrived during a huge southerly swell that was closing out the harbor entrances. The race boats grumbled about being asked to stand off for the night, but they changed their tune when they saw the huge sets of waves.

New toys
Modern technology has given us some great tools to make more informed decisions, assuming we’re paying attention to them. A decent functioning radar should be able to see boat traffic on flat water, the shape of the cliff around an anchorage and the density of a squall about to dump on you. Like any charting aid, it’s important that the sailor knows how to read a radar so they don’t mistake the distant hill for the nearby beach. Waves make radar less effective, and Paul has experienced really hard rain hiding even a containership at sea. This is where AIS comes in handy. When Paul was in that rainstorm, his AIS receiver told him about a large containership that would approach quite close. Because he had the name of the ship, they answered on their VHF and discussed options. When the closest point of approach was down to a quarter-mile, Paul hove to and the other ship stayed on the radio the whole time to make sure he was okay. That improved communication is the magic of AIS. We still have just that receiver, since only the big guys are required to transmit a beacon. This has led to me flood-lighting our sails in an effort to be seen by a fishing fleet one dark night. We will be upgrading to a transceiver in preparation for the Singapore Strait. Anything that improves our visibility is a welcome addition.

We obviously use a GPS, as the AIS will not work without one. We actually have four independent GPS units, along with a couple “pucks” for the computers — you can never have too many spares! We also carry a spare autopilot or two so the inevitable failure doesn’t force us to hand-steer for days. We use a charting program on our laptops and particularly like the GPS-aligned satellite image overlays for areas where the charts disagree (like Tonga).

We sometimes create KAP files using the GE2KAP app, but most common destinations are now available online or from other cruisers. Many cruising sailors these days use an integrated chartplotter/autopilot system, though one memorable fellow was just using his iPhone. He was surprised that he wasn’t able to download new files once he was out of sight of the cell towers on land. Yep, sailors still have to plan ahead to have the charts they need before they leave.

Busy shipping areas require close attention to nearby traffic.

When we plan a course, we scan over the entire length of it zoomed in so we can see any notes that don’t show up when the chart is zoomed out, and I usually do the same on a paper chart just to make sure we didn’t miss something.

For instance, Beveridge Reef is really difficult to find on our electronic vector charts until we zoom way in, but it’s plainly visible on the paper charts. If I right-click on the electronic Beveridge Reef, I see the little note “Rep. to lie 3mi to the NE,” which would remind me to approach in good visibility or give it a very wide berth. Both the reef and its note are visible on the electronic raster charts, which are basically scans of the paper charts and therefore don’t have the sneaky zoom issues. We drop a waypoint on our route at the closest point to a danger — even if we won’t be changing course there — to remind us to be particularly aware as we approach that point. We plot bluewater courses at least 10 miles from any reported dangers to give us wiggle room in case the chart is a bit off or the wind shifts. We pointedly navigate using human willpower at all course changes, rather than an automatic program, to make sure we are fully alert to conditions. Those robots aren’t taking our jobs!

They’re more like guidelines, really
Anyone who has crossed the path of a containership knows that the “right of sail” doesn’t matter when the giant cannot physically change course or slow in less than a nautical mile. The rules of the road also say that motorists should not hit pedestrians, but pedestrians are still expected to look both ways before crossing. Whether we are offshore and seeing our first ship for days or sailing near a busy coastal shipping route, it is the responsibility of every person on the water to keep watch and maintain safe distances.

Offshore, we scan the horizon at least every 15 minutes because a containership at full speed can go from the horizon to uncomfortably close in little more than that time. In busy shipping channels or near land, we aim to have someone physically watching every moment, though we occasionally allow bathroom breaks or a quick grab of a cookie. If this seems extreme, consider how much fun we once had motoring into a big gill net off Baja one night. Paul had to spend an hour with dive gear cutting that net off our propeller while we drifted in the open sea (and the crew watched for sharks). We’ve avoided many gill nets and some small fishing boats by keeping a weather eye open.

Assuming we are keeping our usual 24/7 watch, the purpose of our AIS is to inform our decisions. “All” international shipping is supposed to broadcast an AIS signal these days, and even the fishing boats that turn theirs off near their favorite spots still run lights we can see for miles. The question is what we can do about it, considering the limited maneuverability of our lumbering dance partners. If any ship will pass within two miles of us, our AIS alarm goes off (really, really loud, just in case we got caught up in a podcast or fell asleep). We watch their course and speed data for a few minutes and decide if we should adjust our course.

The big fishing boats particularly worry me, since they work a pattern rather than sailing a straight line, and I don’t know how far behind their lines are dragging. Sure, we could play chicken and hope that they notice us, and that they feel like moving out of the way of our little sailboat. Or we could make a minor course correction miles away and not stress about it. We rarely need to do anything, but it’s nice to have the info to make an informed decision.


A chart view and an info box warning that Beveridge Reef is reported to lie three miles to the northeast.

The evil you don’t see
Modern electronic charts are very useful to inform sailors who are also keeping their eyes open. AIS beacons make ship collisions ever more unlikely as long as anyone on board is awake to notice them. What keeps us up at night are the things that are difficult to predict or see.

We experienced a close call in the wide channel between Oahu and Kauai because another cruising sailboat had forgotten to turn on his lights at dusk. We could see by his AIS beacon that he was on a collision course with us, but it took nearly 20 minutes to raise him on the VHF. By the time we agreed on a course change, we were a half-mile apart and he passed within shouting distance in the dark. I think of ship’s lights as fairly old technology, but in many parts of the world we share coastal waters with local fishermen in small unlit boats. I don’t think any level of “we did our part” would console me if we were responsible for injuring or killing some person out fishing for their family, so we travel slowly and with extra vigilance in those areas.

Successful sailors use all available technology to stay safe, and our eyes are still our most important tool. The awesome technological advances in global positioning, charting, weather predicting and autopilots are tools that serve the eyes and brain, but don’t replace them. Taking all possible precautions means we get to sail farther to more beautiful places, and the crew is happier because we feel safe at sea. So we follow the rules we made to keep ourselves happy: We check and double-check our routes with multiple sources, someone is always on watch to scan the horizon every 12 to 15 minutes and there are alarms set to back up our senses.

Bonnie Wagner voyages aboard the Ohlson 38 Romany Star with her husband Paul.

By Ocean Navigator