There are a couple of notorious sailing passages around the world. We’ve known boats that claim the run between Fiji or Tonga and New Zealand is the toughest in the world. The short sail from the ABCs in the Caribbean to Columbia can be horrendous due to the katabatic winds pouring off the high mountains. We had high winds and rough seas here. Friends of ours almost lost someone overboard.
A particularly tough class of passages are the ones where you have very strong currents in temperate climates. Here, since you have no trade winds blowing from a constant direction, you can get a wind-against current situation, in which the wind can blow the current up into big waves. One of the Gulf Stream along the U.S. coast, which becomes a maelstrom in a northeasterly. Another is along the east coast of South Africa where north-moving storms can hit the south-flowing Agulhas current and make a serious mess.
All this was on my mind as we sat in Richard’s Bay, the northernmost port on this coast in late November, getting ready to sail south and around the cape to Cape Town, a total passage of 900 nautical miles. Our trip would take us down to 34 degrees south and around one of the great southern capes—Agulhas, the southernmost point, not the Cape of Good Hope, which is 29 minutes of latitude farther north. But, there were really only two things on my mind: the Agulhas current and the periodic southerlies that blow up around from the South Atlantic.
I believe few things are rocket science—in fact, rocket science may not be rocket science anymore. Something tricky and difficult like sailing around the Cape Agulhas can be studied and researched and planned for. The only variables are time and energy. If you can spend enough time preparing, and be organized and focused, I believe you can improve your decision-making greatly. Of course, there’s always that other variable of dumb luck. And, in sailing I’ve learned that this one is always present—maybe more dumb in my case than in others’.
As I washed the daily accumulation of coal dust off our decks in Richard’s Bay I watched the weather forecasts on Windy and did more close analyses in PredictWind, where I can look at current models and PredictWind’s own riffs off the two main weather forecast systems—the GFS produced by NOAA in the U.S. and the European equivalent called the ECMF. I began to get very glum. Everything I’d read about this passage said that as southern summer began the southerlies would occur with less and less frequency. But, sitting in Richard’s Bay celebrating our vegan Thanksgiving with some truly amazing potatoes and gravy we just saw southerly after southerly blasting the coast with 20-30 winds and mountainous seas. Where was the break?
Agulhas Current
The main thing on my mind was the current. If we caught a window I wanted to put myself right on the edge of the greatest flow, which would propel the boat south at some really epic speeds. Folks who’ve done this passage said that we could expect to average 10 knots at times. While certainly thrilling, my main objective was to make quick work of this coast and get somewhere safe before things fell apart. In sailing speed reduces your exposure to risk, kind of like how capital can protect against risk in an enterprise.
The Agulhas is one of the strongest currents in the world, carrying almost twice as much water as the Gulf Stream and hitting velocities sometimes three times as much. It begins in the Indian Ocean as the east flowing equatorial current. We’re acquainted with this guy as we rode it occasionally on our way across from Sumatra to the Chagos and the Seychelles. But, there the max we ever saw was 1 knot, and mostly we saw very little.
As the equatorial current nears the coast of East Africa it splits at the border of Mozambique and Tanzania. One part moves north and flows up past Somalia. The other heads south, zig zagging along the coast of Mozambique. By the time it reaches South Africa it rips along at pretty incredible velocities. Boats have measured 6 knots of current at times here.
This is all great when the wind comes from the same direction (behind you) and isn’t too strong. But, that’s infrequent. Much more common are strong winds from the north, which can whip up the current into a rushing frenzy. Much worse is when a low pressure system comes blasting up with winds from the south. Waves that are normally 2-3 meters can get pushed up to 4-6 meters or higher. In fact, this is the part of the world where the largest waves on record—so called rogue or freak waves—have been measured, monsters towering 20 meters or higher. While we planned our trip south I spent far too much time reading through scientific analyses of freak waves or sailor tales like this absolutely frightening account of a rogue wave that dismasted a cruising boat thirty years ago and swept two crewmembers overboard, never to be seen again.
First Two Hops
We finally set out at the beginning of December. Our window was short: four hours of light winds that would build all day into 20 knots or more before coming around on the nose 15 hours later, giving us a 16-hour window. We would need at least 10. We left at sunrise (4 am) and motored for the first bit. Three hours later we were surfing at 12 knots down 2 meter waves with 32 knots of wind at our back. The sun was shining, and on the whole it was a thrilling ride. Still, about three hours out of Durban we dug a bow into a wave, which on a catamaran is a little concerning. (In really steep seas, a buried bow can “trip” a catamaran head over heels.) In response, we pulled down the main to the 2nd reef point and reduced the genoa in half, which helped.
After four cold, rainy days in Durban where we got covered in more black dust, we set out again. This time our window wasn’t quite as good. We were supposed to have some light (10-knot) headwinds for the first part of the trip, then the winds would come around on the beam at 15 knots for a while, eventually strengthening into 25 knots behind us. I expected it to be a bit wet to begin with, but eventually turn out like our trip from Richard’s Bay a week earlier. Like with that passage, we wanted to go fast as the forecast showed the winds strengthening to 27 knots or more before we got to East London, our first possible stop, 250 miles down the coast.
As it happened, those south winds were stronger and lasted longer than forecast. We also had a lot more current. I measured 4.5 knots at one point, and it wasn’t uncommon to see the number 14 flash on our speed indicator.
The Broken Bits
The main thing that went sideways was that we broke a bunch of stuff, and I spent much of the trip fixing things.
The first thing to go, about an hour before sunset, was the bowsprit. Normally we have this thing held on with our spinnaker halyard when we’re not flying our code 0 sail. But, in Richard’s Bay I’d put the halyard on a bow cleat when we were repairing the rig, and I forgot to put it back. The flimsy line holding the bowsprit up broke and the whole thing splashed into the sea. Luckily it was dragging by the two cables that hold it down, and, after slowing the boat and with a bit of struggle I was able to get it back on board and tied up properly. Minutes later the autopilot went on the fritz. I fixed this too, with a master reset, but this is something I need to really dig into.
Later that night, when the winds came up, we chafed through two reef lines, which is a recurring problem on a Lagoon 500. When the second one gave way, the sail slammed against the rigging, which broke the lazy jack system that holds the sail bag onto the boom and shattered topmost batten in the sail. With 25 knots piping up behind us, Jade and I simply took the sail down and lashed it to the boom with a bunch of spare lines. Genoa alone was enough to catapult us at 11 knots. Gotta love the Agulhas.
Lastly, during the daylight hours as we neared East London and the waves picked up, one of them rushed against the stern so hard that it popped the port ladder cover off and nearly ripped the ladder away. I was able to save the ladder, but the cover went swimming. I’ll need to get a new one fabricated in Cape Town.
We surfed into East London with a solid to-do list, which is fine, as the weather shows that we’ll be socked in here while it howls out in the Agulhas over the next seven days.
Window Shopping
“This coast is no joke,” quips my friend John, who is sailing a Lagoon 440, a smaller version of our boat a hundred miles ahead of us. He set out a couple of days ahead of us from Richard’s Bay, trying to make it into Durban ahead of a southerly, and got caught out when it arrived four hours early. “It was horrible,” he reported when we showed up a few days later, wind whipped but healthy. Now, as he sits in Port Elizabeth 120 miles ahead of us where a magnesium mine covers his boat in a corrosive dust (what is it with these South African ports and their dust!) John and I pour over weather maps together on WhatsApp. Is there a window Thursday, we wonder? There’s headwinds, but they’re light. Hmmm. Maybe that’s a recipe for disaster…. He goes off and talks to a few other sailors in Port Elizabeth who are also looking for a window to gather other views. I do the same. We reconvene.
This is basic decision-making in an unclear environment—applicable to not only to sailing but to other things like running an organization. You lean into data gathering, some of which are viewpoints of knowledgeable people. You mix these together and build a model in your mind. Yes, Thursday looks good. The headwinds are light (8 knots forecast, probably 12 knots in reality). The current weakens after Port Elizabeth. Several experienced South African boats are heading out. All good signals.
At this point it’s key to subject the model to criticism. Tear it apart with what ifs. What are the worst cases? Where does the plan fall apart? Those headwinds raise the likelihood of rogue waves, even when they are forecast light. With my family aboard what is my appetite for such an increased likelihood? What if those winds aren’t light and 5 knots stronger—so 17 knots? What if they don’t turn, but wobble along on the nose? If I’m racing the weather, what happens if something disables the boat and I can’t move as fast?
Invariably, this scrutiny damages the model. And it’s easy to fall into analysis paralysis. How do you avoid this? You have to back up and remember that you’re testing your model and understand whether your tests simply make the model more realistic or do they dissolve it like an acid on metal (or magnesium dust on a boat). Eventually, you have to take a view based on whether you believe that the model is too weak or has just been tempered, and is, in fact, stronger. Some people call this gut, but for me it’s more about getting a clearer view of the model.
The rest is up to luck.
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