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Old 02-22-2001
John Kretschmer John Kretschmer is offline
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An Island in the Stream

"In the first place, the Gulf Stream and the other great ocean currents are the last wild country there is left."

     —Ernest Hemingway, in "On the Blue Water," Esquire, 1936


Isla de Mujeres' quaint waterfront—a welcome sight for mariners who've just crossed the Gulf Stream.
Isla de Mujeres, the isle of women, is one of my favorite places. And while there is a romantic story from the past regarding this popular destination off Mexico's Yucatan Peninsula that I could delve into, I think I’ll stick to more mundane aspects of sailing and navigation. A scrubby, low-slung finger of sand, Isla de Mujeres has one of the best natural harbors in the Western Caribbean. It has been a waypoint ever since Mayan mariners landed in long dugout canoes more than a thousand years ago. Like most barrier islands, Isla de Mujeres seems fragile and yet it has withstood the relentless pounding of the trades, frequent assaults from hurricanes, and frightful proximity to the hideous tourist Mecca of Cancun.

The harbor is usually filled with sailboats at anchor and alongside the sporadically planked wharf at Marina Paraiso. Isla de Mujeres is one of those landfalls that breeds camaraderie among cruisers as they compare passage notes. One subject invariably dominates the conversation: how badly did you get stuffed by the Gulf Stream?

Isla de Mujeres is perched on the western edge of the Yucatan Channel, just a few miles off the mainland. Reaching the island from the south is easy—steady easterlies and a favorable current speed you toward landfall. Approaching from the north, or more commonly, the northeast, is a bit more challenging. A powerful north-setting current patrols the 100-mile-wide strait like a zealous Mexican customs agent and at times the drift is more than four knots. Once above the strait, the current splinters. Most of the warm, steel-blue water seems to be directed into the main body of the Gulf Stream that gathers steam as it nears the Straits of Florida. A loop current is also spawned and it usually sets north into the Gulf of Mexico and then hooks back to the southeast to connect with the Gulf Stream west of the Dry Tortugas. Together these currents conspire to make all passages from Florida to Isla de Mujeres interesting, to say the least.


The twin-helmed Catalina 400 proved an able passage maker.
I just returned from an offshore training passage aboard my friend Ed Hershman’s Catalina 400. We sailed from Key West to Isla de Mujeres and back to Ft.Myers, FL, a wedge-shaped passage of 750 miles with a refreshing respite on the island. Naturally our biggest concern on the passage was how to contend with the Gulf Stream. We wanted to minimize its impact on the outbound voyage and take full advantage of its magic-carpet-like qualities on the return voyage.

Statistically the Gulf Stream staggers the mind. At the height of the current in the Straits of Florida, more than 30 million cubic meters of water are moved per second, that is a total of 90,000,000,000 tons of water in an hour. To put that force of water into perspective, consider this: if you combined the Amazon, the Mississippi, and every other river that empties into the Atlantic Ocean, they would move a whopping 0.6 million cubic meters per second. What do these statistics mean to sailors? It’s simple—don’t buck the current if you can avoid it.

We cleared the Key West Ship Channel just before noon. The weather was a bit unsettled, but the long-term forecast called for steady, 20-knot easterlies, perfect winds for the passage. The crew consisted of four relatively experienced sailors making their first offshore passage: John from Michigan sails a Catalina 28 on Lake Erie. Jerry from Madison, WI, sails a Seaward 25 on inland lakes and has also chartered in the Caribbean and on Lake Superior. Bob from Wisconsin as well races whenever he can and is on verge of buying his first large sailboat. Russell from North Carolina owned an Island Packet 31, but never sailed it offshore. And Ed, the owner of the boat, has accompanied me on several offshore deliveries, but was thrilled at the prospect of making an international landfall aboard his own boat. We were packed in like foul-weather-cladded sardines despite the Catalina’s spacious interior and comfortable cockpit, but the nature of an offshore passage means that the crew is rarely on deck or below at the same time.


En route, the crew was able to make the most of 15 to 20-knot easterly winds.
Before sunset the winds had steadied at 15 to 20 knots and we were making good progress, at times sailing wing and wing. Sooner than expected, however, we had to make a tactical decision, the Gulf Stream was slowing our progress. One of the great attributes of GPS navigation is that SOG (speed-over-ground) and COG (course-over-ground) features make it obvious if a current is affecting your progress. Also, the log had a convenient water temperature setting. The waters just beyond the Key West Ship Channel hovered around the 75 degrees Fahrenheit range. Upon entering the Gulf Stream, they immediately shot up to 78 degrees.

If you glance at the enlarged pilot chart of Central American waters for the month of February it will reveal the general tendencies of the current. The thin green line shows the strength of the current as it pours out of the Yucatan Straits and curves close around Florida. It also shows the loop current, stretching above 26 degrees into the Gulf of Mexico. It reveals the counter current spawned by the Gulf Stream’s eddies just along the Cuban coast. Pilot charts are invaluable planning aids. However, they can’t help you with one frustrating aspect of the Gulf Stream; the main body of the flow shifts position from day to day. This fact irritates my dear friend, fellow delivery skipper and Gulf Stream veteran Captain Bob Pierce. "It isn’t enough that the damn current stuffs us every chance it can; it also moves around; it just isn’t fair." This is where Jenifer Clark comes in.

Clark is a professional satellite oceanographer. She spent 26 years as NOAA’s Gulf Stream expert, now she has her own company and offers satellite images to sailors. Using infrared imagery, satellite altimetry data, and surface temperature isotherm data, Clark pinpoints the location of the stream and its many eddies. As some of my more thorough readers might remember, I am not a great fan of weather-routing services, especially for ocean passages of more than a week. However, on this short, 320-mile jaunt to Isla de Mujeres, the position of the Gulf Stream is the critical element of the passage. It seemed foolhardy not to invest $35 for Ms. Clark’s latest Gulf Stream chart of the Gulf of Mexico.


Surface-water temperatures like those depicted in this full-color chart provide the best clues regarding the whereabouts of the whimsical Gulf Stream.

Just before leaving for Key West I printed out a full color chart showing (by SST or sea surface temperature) the location of the Gulf Stream and more importantly, the loop current. Clark includes written comments and a guide to interpreting her charts. She was amazed at how far north the loop current stretched. The chart also indicated that by the time the loop current rejoined the Gulf Stream near the Keys, it was well to the north of its usual position noted on the pilot chart.

There are two general routes to Isla de Mujeres from Key West. If the Gulf Stream is in its likely position, favoring the Cuban side of the Straits of Florida, then a route that stays above the current is possible. Of course this route can become difficult if the loop current is running strong, making it tough to drop down into the Yucatan Channel from the north. It may be necessary to sail west of the Yucatan Peninsula and then circle back to the southeast. Many years of making passages to Panama and the Western Caribbean have proven to me that a better strategy is to cross the Gulf Stream at a right angle and sail south until you’re just off the Cuban coastline. There you will likely find a favorable counter current as well as favorable winds. Of course, in the old days it was downright frightening to be within sight of Cuba and you hoped to avoid an encounter with Cuban authorities. These days Cuban waters are fairly teeming with visiting yachts and while a gunboat may still stop you, it is not likely that your passage will be unduly delayed.

Naturally, we didn’t take either of the two routes. Working our way southwest, it became apparent that although we were bucking the current, we were still making good speed. The broad width of the current had diffused it slightly, the drift varied from one to two knots. With the stiff easterlies hurdling us along on a lively broad reach, we were sailing at seven  knots through the water and usually netting about five-and-a-half over the bottom. Although the waters were a bit lumpy because the wind and current opposed each other, it was clear that the rhumb line represented the fastest way to Isla de Mujeres. Another factor to consider was that by staying on rhumb line we had a nice, comfortable point of sail. If we chose to slice down to the Cuban coast early on, we’d be forced to sail dead down wind, which as we all know is the most overrated point of sail.


Follow the arrows—the author and his crew also relied upon charts like this one to determine how the Gulf Stream loop was positioned.

We eventually closed the Cuban coast as we neared Cape San Antonio. The final approach to Isla de Mujeres finally uncovered the full force of the Gulf Stream. The last 15 miles found us battling an impatient three-knot set going north and it was a bit of a struggle to clear the island’s southern tip. We made a careful approach in the darkness, with Jerry and Bob plotting GPS approach waypoints and choosing safety coordinates. Russell and John used sharp eyes to spot the light at the Boca La Bandera, an aptly named rock in the middle of the approach, and Ed conned the boat from the low-side wheel (the Catalina 400 has twin wheels.) We dropped the hook in the lee of the island around midnight and by 0800 the next morning we had the boat secure at the dock and I began the form-filling madness of officially entering Mexico.

After a delightful 24 hours ashore, we set sail the next morning on our return trip to Ft. Myers. We passed over the submerged reef north of the island, a shortcut we wouldn’t have dared in darkness, and aimed northeast, hoping for a kick from the current. It took some time to notice any obvious effects from the current, although we were thankful that the wind had clocked a bit, allowing us to steer close to the rhumb line of 040 degrees. It was just over 400 miles back to Ft. Myers and depending upon the current we hoped to complete the passage in less than three days.

The loop current finally arrived in dramatic fashion. From a distance we noticed what appeared to be a breaking reef off to the east. We knew this wasn’t possible, but the breaker line was distinct. Inching ever closer, it soon became obvious that the wall of water marked the edge of the current. Lines of sargasso weed indicated the edge of the current as distinctly as the dotted lines of the pilot chart. The motion also changed and Jerry noted in the log after his watch, "We’re back in the odd chop of the stream." Soon we were being whisked north at eight-plus knots. Occasionally we topped nine and even hit 10.4 knots once. Unfortunately, the strength of the current flattened out our course and although we were sailing hard on the wind at near 050 degrees on the compass, we were lucky to net 020 degrees over the bottom.

Rain squalls are a constant feature of the Gulf Stream, and twice we had to shorten sail urgently as dark clouds produced short-lived blasts of wind that demanded our full attention. Eventually we angled out of the current and pointed the bow in the direction of Ft. Myers. North of the Dry Tortugas the sea conditions changed dramatically. The sea temperature cooled and lumpy conditions turned into gentle wavelets as we entered the vast lee of Florida Bay. Although we were still close to 100 miles offshore, we were on soundings, a feature of Florida’s west coast that I don’t like. Air temperatures also cooled, flying fish no longer hurled themselves across purplish whitecaps, and the noticeable humidity that hangs over the stream like a damp shower curtain also vanished. By the time we made landfall in foggy Ft.Myers, the Gulf Stream was a distant yet pleasant memory.


Suggested Reading:

The Basics of Crewing by John Kretschmer

At Odds with the Weather Gods by John Kretschmer

Understanding Tidal Currents by Jim Sexton

 

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