That gut feeling …

The Tuamotus Diaries #57, Day 120 – September 25th 2016

We are in Toau – the third Atoll we visit in the Tuamotus, and the last.

We arrived here the day before yesterday, Friday, after an easy day passage from Fakarava.

It was exceptionally mild upon arrival, and the Atoll was in full splendor. The forecast, however, was promising “normal” (aka Very Windy) conditions to resume on Monday again, so we tried to take the most of our time. Snorkeling, walking on the beach, visiting a portion of the motu nearby.

Today, Sunday, the wind started to pick up more or less in the middle of the morning. It was a gradual, subtle strengthening. From a near-calm during the night, it accelerated to a light breeze just before noon. It was all gentle, the sky remained clear, the Atoll and the crystalline water all sparkling around us.

And I started feeling uneasy.

I couldn’t put my finger on it. All looked good, but that slight breeze just unsettled me.

I downloaded another forecast package, and everything insisted the winds would pick up only tomorrow, when they would accelerate to approximately 17-20 knots.

Hmmm … but that gut feeling …

Using the crystalline waters and the swarm of fish under Pesto as an excuse I got my mask and flippers and dove to check the mooring that we were using. The system was composed of a sturdy 1-inch nylon rode. Near the bottom, a length of chain had been wrapped around a coral head, and the rode tied to it. It all looked sturdy and in good integrity.

But that gut feeling …

Moorings are cool. They are a nice way to protect the coral, for boats don’t need to drop their anchors, tying to the moorings instead. However, I don’t like them much. First off, Pesto is heavy, definitely on the heavier end of the average cruising boat here. Moreover, she loves to sail while tied to a mooring, thus adding more stress to the system. But the fundamental diatribe I have with a mooring is the stealth nature of they failure. If a mooring breaks, your boat is set loose without any warning, and with anything to hold it back. It will just drift silently until hitting something. An anchor, on the other hand, may even drag, but not without a fight, thus providing warning in the form of noise and vibration, and some much-needed time for reaction.

Ok, back to the story. Still trying to honor the mooring system, I decided to set up a redundant line. It was deep, 50 ft, but my gut feeling was a strong incentive to try harder. My goal was to tie two of my own lines to the chain, and leave them slack. Just as a backup in case the original rode snapped. Two large Groupers watched my efforts to reach the bottom with some disdain, as if knowing I was off to being defeated. Indeed, after a couple of tries, it became clear I didn’t have enough air left in my lungs to tie the line to the chain and return to the surface alive.

The little I was able to stay near the bottom, however, was enough for me to notice the chain was substantially smaller than the one we use on Pesto for anchoring.

But it is still chain”, I reasoned “… and it withstood the whole season, potentially with hundreds of yachts using it without a glitch. We should be alright.” I reasoned further.
But the gut feeling had now been upgraded to anxiety. Not only was I not able to set up a backup for the mooring, I was now aware (and dissatisfied) of the size of the chain fastening us to the coral.

I stood on deck, watching loosely around us, trying to gather some hope that the weather wasn’t going to be bad.

But the gut-feeling-turned-anxiety wouldn’t let go of me.

And then I realized that patch of light green water some 100 meters ahead, closer to the reef upwind of us. I invited the kids to come with me, and together we went to scout the place. My heart filled with hope when I realized the patch was indeed a hump of sand that came at a steep angle from the coraly bottom, some 60 ft below, up to a shallow depth of 20 ft. It was indeed a perfect spot. Just that hump of sand, without coral heads or anything to snag, damage or be damaged on a 100ft radius.

Back to Pesto, Reason continued to question me, and the need for all that fuss, since we looked securely fastened to the coral via the mooring. “Why not wait until tomorrow?”, Reason said.

Seeing my puzzled expression, Adriana, who was cooking and rather oblivious to all that happened up to that point, asked what was going on. I explained, she listened, and came straight on deck, leaving knives and vegetables on the galley counter, saying that we should move to the sandy hump asap. After so many miles together, she has learned to trust my gut feelings more than I do.

The engine fired up, I let go the mooring line, we proceeded to the light-green patch, and dropped our mighty anchor there. As we moved, I could sense over my shoulder the puzzled expressions of our two neighboring yachts, and an uncomfortable stare from the family that lives onshore. But I KNEW we were doing the right thing. Should conditions go bad, it would be far safer for us to be anchored on that sandy patch than tied to a mooring. Besides, our scouting confirmed our chain would only meet with loose sand there, and not bother or be bothered by any coral.

Anyway, our mighty anchor went down, bit the loose sand ferociously and we made ample use of reverse gear to incentivize it to dig even deeper. I was still at the bow, tying our snubber, when I noticed a peculiar line of clouds at the horizon. The gut feeling subsided. Now I KNEW the forecast was crap and that something intense was about to happen.

With Pesto now securely anchored, I could sit and watch the spectacle. That thing approached us from the Southwest. It was a blanket of clouds, not too thick, and with a nearly-perfect straight edge spanning all the way across the sky on a line from SW to NE. It was not a squall. They were not heavy, dark clouds. Rather, a moderately thin layer of clouds, homogeneous and soft as fleece, with a pastel color with hues of beige and light grey. It passed over us, casting the fleecy blanket over our sky, and an utter silence reigned. Reason was about to start questioning my guts again when it happened. Within some 10 minutes the wind picked up substantially, and by sunset it was blowing a steady 25 knots, with gusts surely reaching 35, if not more.

The sun setting under the blanket of clouds … we still didn’t know by then, but we were in for a full five days of a continuous blast of 25-35kt winds.

I downloaded yet another forecast package, just to check mine and its integrity. It was still reassuring me of 17-20kts STARTING TOMORROW. “17-20knots my %^&%*”, said Reason, somewhat humiliated by the recent lesson from my guts.

The wind is howling outside, Pesto heeling successively to port and starboard. At least the water around us is calm, since we are on the lee of a reef. I know I will wake up a number of times to do anchor watches during the night. But had we been on that mooring by now, I would for sure be awake all night. And God forbid me thinking what would have happened if that mooring was to snap during the night in these conditions. With less than a minute to react, and the wild ocean now frothing over the coral just a couple hundred meters behind, it wouldn’t have been pretty.

One thing I have learned on sailing is that our Guts have a voice, and they are often right.

The other is that Preparedness goes a long way in offshore cruising.

 

POST SCRIPTUM – AFTERMATH:

The wind blew consistently above 25Kts for 48 hours straight, from that Sunday afternoon, and then receded to around 20 knots, and continued blowing that way for another 48 hours. It s worth mentioning that the forecast consistently underpredicted wind speed – by 5 to 10 knots during the first 48 hours, and by ~3 knots for the remainder of the time.

This experience ended up being a substantial test to our anchor for the following reasons:

  • The bottom was composed of a coarse “sand”, made mainly of fragments of coral. It was light material, and loosely arranged at the bottom. It wasn’t as strong a holding ground as regular sand, or thick mud for example
  • We anchored in an area prone to currents: approximately 2 to 3 knots when it was ebbing (twice a day) and just under a knot when it was flooding (also twice a day). When the current was ebbing, it was in the same direction of the wind, thus adding to the static tension on the chain and current. When it was flooding, it was against the wind direction. This caused Pesto to sail significantly, at times accelerating to 1knot in between “tacks”, thus imposing significant dynamic loads to the chain and anchor

I dove daily to check in the status of the anchor, and it didn’t move an inch, despite the relatively poor holding.

As I expected, the chain didn’t interact with any coral formation other than this sand, even with all the sailing that Pesto did during the event. And that was another learning from this experience.

When the wind started to blow, Pesto started sailing at anchor. This was expected, since she tends to sail when the winds freshen. However, this time the amplitude and the speed of sailing appeared to be higher than at other times. I reduced the exposed surfaces to the wind to minimize the effect (folded the paddleboard, tilted the solar panels, and removed much of our awnings), but with no effect. Over time, and studying the movement, I identified two independent factors underlying the augmented sailing:

  • The profile of the bottom: as mentioned before, we dropped the anchor atop a small hump of sand which raised steeply from a deeper bottom. As a result, the anchor lay at around 20ft depth, and the chain then dropped along the face of the hump to a depth of ~40ft before turning up again to Pesto’s bow. But with the strong wind pulling hard against the chain, it in fact “floated” for most of the time, thus hardly touching any ground. So, in practice, even though we had a lot of chain out (~140ft), it offered very little lateral resistance due to the lack of friction with the ground, thus letting Pesto free to sail
  • The Current: when the current was ebbing, thus flowing parallel and in the same direction of the wind, Pesto sat still, hardly sailing at all. However, when the tide turned to flood, it “pushed” us toward the anchor. The chain got slack, but because of the steep aspect of the bottom (see “1” above), it still “floated”. With the chain well slack, and offering little lateral resistance, Pesto felt free to sail significantly to all that wind.

And sail she did. I left the chartplotter on during all five days of this experience and during that time she logged a disturbing 1.76 miles !!! When the wind was strongest, and the tide flooding (that is, opposite to the wind) Pesto covered arcs of up to 100 feet in length, often reaching speeds of 1 knot in between tacks. Luckily we had ample swing space and my piece of mind was the only thing to be bothered by all that movement during those five windy days.

This picture shows Pesto’s track as it sailed in arcs against the anchor and chain during the 5 days of winds. The arcs are the red lines – she covered just under 2 miles of sailing at anchor during those 5 days. The anchor was positioned more or less where the white cross is on the picture. At the time I captured this image, winds were lower and Pesto was sailing at “just” 0.4 knots in between the tacks. We often hit – or exceeded – 1 knot when the winds were stronger.

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