The Drag Coefficient

50 knots of wind stir up the anchorage
in Bahia Salinas, Costa Rica.

A QUICK EXPLORATORY DIVE, on Anna's bottom, told us that she would never attain escape velocity with the thick forest of marine growth, which had attached itself to her rudder, propeller, and keel. Swimming through a countercurrent, against headwinds and short-period wind waves, off her starboard bow, Anna's speed would be reduced to a crawl, 2 to 3 knots, maximum. A high coefficient of drag would reduce her speed by approximately one half. And with a promising, but small, weather window opening up, we could hardly spare the extra time, which the loss of a couple of knots of speed represented. We had a 36-hour excellent weather forecast to make 192 nautical miles - the distance between Golfo de Fonseca, Honduras, and Bahia de Salinas, Costa Rica. 

Bahia Salinas, Costa Rica during a Papagayo wind event.

After that, the wind and waves would likely turn severe, yet once again; a full gale was threatening the tail end of the 72-hour wx forecast. January, February and March are difficult along the Pacific coast of Nicaragua. The heavy winds and steep, short-period wind waves have been relentless. And a favorable, 72-hour break in the weather, a rare commodity, held great promise. We saw one taking shape, the computer models were all in agreement, and it was time to go - time for our fourth attempt to negotiate the coast of Nicaragua, nonstop to Costa Rica.

Anchored one-half mile off the beach
 at Bahia Salinas,.in a gale.

To take care of the marine growth on the keel, we dove and we scraped and scrubbed the rudder and prop and waterline sections until they were clean and relatively smooth. In addition, while we were under water, we removed and replaced the depleted sacrificial zinc that is attached to the drive shaft. But there was still a lot more to do. The entire keel and especially the bottom of the keel had accumulated perhaps, a one-half foot thick layer of algae, anemones, and scattered, tenacious barnacles. We knew a panga fisherman, in Honduras, who had come to visit Anna with his family, one day, and we asked him if he knew of anyone who could free dive to clean Anna's keel. He told us that there were spear-fishermen that he knew, who could stay down for about three minutes at a time, before surfacing for air. Next day he dropped two of them off, where we were anchored, and they agreed to clean the heavy growth off the bottom - their ability to free dive allowed us to save our scuba tank air supply for other maintenance or emergencies that required us to stay under for 15-30 minutes at a time. Two hours later, they had completed the job, from where we had left off. It's a hard job in waters with strong currents, and where jellyfish drift by. Jellyfish sting, and it burns; you need to keep one eye on the job and the other on the lookout. But these guys were used to jellyfish. They grew up as fishermen, catching lobster and shrimp and rock fish; spending half their life in the water, the other half on the water, in their small lanchas.

Bahia Salinas landscape.

After cruising and anchoring out, for three months, in Golfo de Fonseca - which is split between three countries: Nicaragua, El Salvador, and Honduras - we were ready to depart. But we were still somewhat reluctant to leave, as we had not seen another outsider for the entire span of time we were there. It felt truly foreign and we very much enjoyed that aspect of the time we spent in Fonseca. The small islands and primitive fishing villages on the Pacific side of Central America afford this sort of opportunity. By and large, the experience was unfiltered, unsanitized; for better or for worse. We found it to be better, but we imagine that others wouldn't agree. After all, we were the only voyaging boat that the locals had seen in the three months that we were anchored out there. The last boat that they remembered seeing, and staying for a while, was six months prior.

Bahia Salinas is an open anchorage set deep within the bay.

With Anna's clean keel, and outstanding 72-hour marine forecast still holding up as the week progressed, we slipped out of Honduras and zipped right along at 5-6 knots, making the passage to the border of Nicaragua and Costa Rica in twenty-seven hours. It felt good to have this unforgiving stretch of coast behind us. It was our fourth attempt in three months - we had to turn back three times because of rough conditions along the way. But on our fourth attempt, the stars lined up.

When we arrived at Bahia de Salinas - in the northwest corner on the Pacific side of Costa Rica - the waters inside the bay were smooth, as it had been for the entire passage along the Nicaraguan coast; a 12-knot breeze and small, long-period swell off the starboard bow. A rare occurrence in the months of January, February or March. And so we settled into the expansive, open anchorage of Bahia de Salinas. The sea floor was uniform, with 15-20 feet of hard-packed sand below the keel. Perfect.

Sunset at the flat, protected anchorage of Bahia Santa Elena,
15 nm  south of Bahia Salinas.

And then the breeze picked up. By late night, the Papagayo gap-winds were blowing moderately hard, once again (30 knots). In the anchorage, the ENE wind waves built to two feet in just one half of a nautical mile of fetch, the distance between Anna and the beach. Whitecaps covered the waters. By the next morning we were in the teeth of a full gale - the wind was howling and registering a steady 35-45 knots, with frequent gusts to 50+ knots. Now the seas were completely white capped with foamy spray blowing off the tops of the wind waves. Still, it was remarkably comfortable on Anna. We did have to close the hatches and ports to deaden the noise of the screaming winds, and one of our anchor snubber lines (3/4-inch three-strand nylon rode, with a heavy-duty fire hose chafe guard) parted, after a week's worth of stress, where it passed through the chock and chafed through the fire hose and then the line itself. The waves put great tension on the lines, then relaxed, then stretched. Over and over again it played out this sawing action until the line snapped. We use a double-line bridle, so while one side did snap, the other side of the bridle took over the job of handling the stress loads until we could jury rig a replacement for the line that parted, and once again, equalize the load.

Panga fishermen at work in Bahia Salinas.

On the flip side, the air was refreshing and cool. Quite a change from the typical heat and humidity elsewhere. And the wind generator was putting out 10-17 amps per hour (nominally, we expect to see 1 to 3 amps per hour, in 10 to 15 knots of wind. But wind power is exponential, and when it blows 40-50 knots, continuously, for ten days, we have energy to burn. Combined with our solar panel array, which put out about 5 to 7 amps per hour, during the sunny part of the day, we were seeing a total of about 375 amp hours of energy coming in to the battery banks, per day. We could run computers and refrigeration and download wx data from the SSB radio, and still not come close to running a deficit of energy. Anna's 500 amp-hour, 12V battery banks were topped off, at full capacity, the entire time we were anchored at Salinas (11 days). This was the windiest anchorage we have ever been to; that is to say, sustained winds, of 40 to 50 knots, for ten continuous days. We were pinned down there, with no possibility of moving along to a new anchorage, until the strong Papagayo gap-winds subsided. Bahia Salinas is the impressive epicenter of the Papagayo gap-wind effect.

When it did finally subside (to 25 knots), we continued south, on a broad reach, along the outer, western coast of Costa Rica, and then around the first major headland to Golfo de Nicoya where we spent the next few days relaxing in calmer conditions - out of the influence of the strong northeasters. After a good rest we continued along the central Costa Rican coast to the lush, jungle terrain of the Osa Peninsula, and then on to Golfo Dulce in the southern sector. One thing is for certain: Costa Rica is varied in climate and topography, and rather different, geographically, than its neighboring countries to the north and west.

Anchored off the jungle, north of Rincon, Costa Rica.

It wasn't until we arrived at some of the more remote, tropical anchorages in Costa Rica that we saw monkeys and parrots in the wild. The northwest sector of the country has a stunning windswept seascape and moderately hot climate. By the time we reached the southern sector, along the Osa Peninsula, in the far north region of Golfo Dulce (just to the north of Rincon) the air and water became quite still, very humid, extremely hot. Oppressively steamy. But the steamy atmosphere had its rewards.

Shading the topdeck on Anna in the burning sun.

A cockpit shower to cool off
at the jungle's edge.

We had anchored fifty feet off the edge of the jungle and the sounds of a plethora of tropical birds and insects and creatures we have never heard before, in the wild, were both enigmatic and hypnotic. Sounds that we never knew existed. Howler monkeys and varieties of parrots and ringing, tingling insects created a primitive soundscape continuum. And the sounds differed radically, from one hour to the next,  during daylight, and after nightfall. The dark, murky waters in the northern gulf were highly bioluminescent as well.

A yellow-footed boobie hitches a ride down the coast.

After three weeks, in Costa Rican waters, we packed up and sailed overnight, around Punta Burica, located at the extreme southeastern point in Costa Rica - the international boundary between Costa Rica and the Republic of Panama. We arrived at Punta Balsa, just across the international boundary, in the pitch black of night, at 0245 hours.

Beach hut at Punta Balsa, western Panama.

We could hear the surf breaking on the beach, close by, but we couldn't identify any hazards visually (and to be sure, there were hazards at hand), so we made the final approach, very slowly, by electronic charts, sonar and radar. We found what appeared to be a 20-foot shelf of sand and dropped the hook. It set well. We then cleaned up the deck, bagged the staysail, went down below and crashed.

Punta Balsa surf break, off the open roadstead.

When we awoke the next morning and took a look outside, we could see surf breaks and reefs in close proximity, but our location was perfect and so we decided to stay put an extra day, to catch up on some sleep before continuing east in Panama's western sector.

Punta Balsa anchorage.

The ride from Costa Rica to Panama was smooth and uneventful, from a sailing perspective, however, it was far from routine. As night approached, the new moon was setting and left the sea jet black. The lower third of the sky was covered in massive, vertically-stacked dark thunder clouds, with black bottoms (visible at night). The clear center of the sky revealed a bowl of twinkling stars, the most prominent in the north being the Big Dipper, and in the south, the Southern Cross. At about 2000 hours, the ocean waves lit up in an extraordinary display of intense cadmium-blue/argon-green bioluminescence. It was so brilliant at times, that it lit up the cockpit. Anna's bow wake generated sprays of luminescence across the bows and along the hull. The three-bladed propeller carved a comet tail of cadmium-argon diamonds for fifty yards astern. At midnight, distant lightning flashes electrified and burnt the dark sky. And together, the intensity of the bioluminescence in an otherwise black ocean, and the steady, arrhythmic, stroboscopic flashing, in the lower third of the sky, revealed powerful forces of nature that we have rarely experienced. A type of wildness that could only occur on the late night watch, at sea.

Small beakers to the left of Anna at Punta Balsa anchorage.

We continue our determined progress toward South America. And we also continue our ongoing, improvised repairs at sea. The latest repair necessitated stripping off a small section of the top layer of plastic laminate on one of our six solar panels, which shorted out due to salt-water penetration at the terminal connections on the top face of the solar panel. Routing wiring out of the top surface of a solar panel, designed for marine applications, is a design flaw, a bad idea. The fix required peeling off a small section of plastic laminate and cleaning out the damaged (corroded) strips of metallic foil that connect to the negative and positive leads. We had some spare copper foil and cut two narrow strips of it, then soldered these strips to close the circuit, that is, to bridge the gaps left behind in the wake of salt-water corrosion that had managed to destroy the electrical continuity. After isolating and soldering the new copper strips and terminal leads in place, we sealed the repair with a layer of two-part epoxy. Then covered the epoxy layer with another layer of 3M 5200 sealant, to waterproof the entire repair area. It wasn't a difficult repair to make, fortunately we had the right materials to complete the job, but it is the sort of thing that happens on a regular basis on a voyaging boat. It's important to try to effect critical repairs while underway, if at all possible. It's often the only option available.

Boomer at Punta Balsa anchorage.

We departed the rolly, open-roadstead anchorage at Punta Balsa, Panama to continue on to Boca Chica, where we would stop for a couple days to catch a bus up to David, Panama, second largest city in Panama, where we could do some provisioning, and also clear into the country at Pedregal, a couple miles down the road from David. It was late afternoon as we approached the entrance channel, at Boca Brava, which would take us to a protected anchorage, four miles west of Boca Chica, for the night and then continue on to Boca Chica the following morning at high tide.

Enroute to Panama.

The weather was benign, the breeze was very light, and the seas were smooth as we crossed Bahia de Charco Azul from Punta Balsa to Boca Chica. As we got closer to the entrance channel, at Boca Brava, we noticed that the swells began to gradually grow in size, from 3-4 feet to 5-6 feet. And the depth of the water began to drop, slowly, from 200 feet to 15 feet at the final approach to the channel. And then things quickly got interesting. Ahead of us we could make out breakers and large 10-foot standing waves that curled and broke at the crest and sent off spray. The closer we got to the channel entrance the larger the swells became. We still had five nautical miles to go.

Small beach house at Bahia Salinas, Costa Rica.

And then things changed. We were one hour past slack tide, which had turned to flood. Normally a good thing. With a light wind and a flood current - just after slack tide - moderate-sized following swells are usually not a problem when entering a narrow channel. But this was different. The waves rapidly transformed into large breaking waves. The waters to our port side were filled with standing waves. To our starboard, large seas rolled by with the top third of the waves breaking off, similar to a heavy surf. Just ahead of us we could see turbulent white-water, and the backs of the swells curling and sending off a wall of spray straight up. And on our six, were swells that had increased to a height of fifteen feet. One after the next, with a 15-second period. These swells were shaped differently than deep ocean swells. They were not rounded, moving mountains that moved slowly, but rather fast and sharp-peaked. They rose quickly and dropped off quickly over the shallow waters that we were in. 15-foot swells, 15-second periods, 15 feet of depth, and then we noticed the GPS speed, in knots, as we slid down the peaks: 15 knots.

Technically, we were surfing a very large, long board, named Anna. For about thirty minutes, as the waves approached from astern we tried to take them dead astern, lifting, and then nearing the peak, sliding down the face on a thirty-degree angle so as to surf down the slopes instead of dropping the bow and nose-diving. This was working very well, but with a few miles still to go, and the swells getting even bigger and breaking harder all around us, we thought that it might be time to do a 180, and head out to sea, into deeper, smoother waters, if we still could. It was getting very dicey. And where was that damn, high drag coefficient when we really could have used it, to slow the boat down? We simply didn't know if the breaking swells would get worse as we continued to surf. Our decision was to reverse our direction - within the 15 seconds we had between wave sets, and then climb the oncoming waves - straight up and over the top, dropping down the backside on a angle; the reciprocal of taking the waves from astern. This too was successful, and Anna slid along as if it was a Sunday stroll in the park.

Our forward speed dropped from 15 knots to 3 knots as we now had to swim against the current, but soon we were beyond the influence of the indifferent entrance channel, and the waves were once again small (5 to 6 feet), and the ride, to our relief, uneventful. We continued past the north side of Isla Parida and then took a left turn around the southeast side of Boca Brava, to enter the safe route into the channel leading to Boca Chica. Just before Boca Chica we found calm water on the north side of Islas las Ventanas. The large southern swell would not enter these waters and that would mean a restful night's sleep.