Illuminating the Fog

I've waited almost a month to post this. Mostly because I've been savoring the feeling of having put together information from various sources and all on my own coming up with an explanation for an observed natural phenomenon.

Okay, really? I've waited so long to post this because one of you will probably tell me my explanation is incorrect.

I've been inordinately proud of myself, and I didn't want to pop that bubble.

So here's the deal: Several times over the past six weeks or so -- most recently two mornings ago -- I've noticed some very localized fog over Gulf waters.

In the West Delta field, one drilling rig might be completely in the clear as the sun rose, while another rig two miles away is shrouded in gray.

On the previous boat we carefully logged the dewpoint, relative humidity and temperature each day; I assumed this was to aid in the prediction of fog during the coming 24 hours.

Of course those factors most directly impact the formation of radiation fog, which is mostly a land-based phenomenon.

Of greater concern to mariners is advection fog, or sea fog, which forms when warm, moist air moves across cooler water, causing the warm air to contract and condense.

My question was: why over here, and not over there?

Seawater, particularly deeper water in a relatively large basin such as the Gulf of Mexico, change temperature only slowly. It's one reason coastal South Texas enjoys more moderate temperatures year-round than, say, Dallas or even San Antonio.

One day as we were plunging into the gray, I noticed a "rip," or line of foam that denoted a current in the water. On one side, the opaque green of the nearshore Gulf; on the other, a silty brown. I thought about this, and decided that the brown stuff was Mississippi River water, floating on top of the heavier salt water.

It also occurred to me that these eddies or currents of river water were probably cooler than the surrounding Gulf water. (I could find nothing on the interwebs about river water in the Gulf, or surface water temperatures for the areas I was looking at, by the way.)

And sure enough, that fog bank started on the other side of the rip and appeared to cover only the brown water.

So, that's my explanation for localized advection fog in this part of the Gulf: river water which started as snowmelt in the continent's heartland remains cooler than the Gulf of Mexico as it flows into the sea, and fog forms over it even when the surrounding Gulf waters are not cool enough to support the phenomenon.

Did I get it right?

Tension and Contention

Things have been a bit tense on the boat this week.

Not sure why – could be I’ve been a bit peevish; dirty dishes in the sink and dead fish on the deck three days running when I come on watch, well it begins to annoy. As does being one of just two people (of the five on board) actually grinding and painting with a shipyard deadline looming.

So maybe it’s just me. Maybe everyone else is fine. Anyway, not a huge deal, just not optimal.

This week has introduced a couple of firsts. For the first time I became really, really angry with someone associated with our customer.

I woke up Friday night to the smoothly-surging-forward feeling of the boat cruising hooked-up across flat water, and deduced (correctly, as it turned out) we were headed for the dock. Checked with the captain on watch and found out we’d been sent in to pick up equipment and some passengers. 

Cool. I wasn’t able to get a card in the mail before we left Wednesday, so this will give me the opportunity to place an Internet flower order to be delivered on my wedding anniversary.

About an hour-and-a-half after we get in, our deck is packed. I’ve already been ignored once by a new dockhand when I told him those full totes need to go on the port side, not the starboard side, and argued with the new crane operator about where a 5-ton generator should go.

The aforementioned, plus another rigger, troop up to the wheelhouse to bring me cargo manifests, and one says: “Your radio ain’t working? Man at the office been trying to call you for the last hour and a half.”

I check the company set: yep, it’s turned up.

“It’s working,” I say. “Tell him to call me on the company set.”

The man at the office did, and proceeded to dress me down for not checking-in on VHF 19, implying a.) I don’t know how to use a radio, and b.) I don’t know my job.

A couple of problems with this: First, his tone – whoa buddy, slow your roll! Second, for the 13 months this boat has been on the job, no one has ever asked us to communicate with the dock on 19. Third, we have three VHF radios installed on the boat, and in the port environment monitor three separate channels for regulatory and safety reasons. Fourth, I wasn’t even on watch when we got to the slip.

I decided a face-to-face discussion might be more productive, so donned my hardhat and walked the 100 yards to the dispatch office.

Turned out not to be more productive after all, and ended with the dispatcher threatening to call our company’s sales manager (I’ve since given him that individual’s mobile number and invited him to call any time).

This particular dispatcher is new to our dock, came over when the logistics company added our customer’s construction boats to its production boat business. 

Over the past two weeks, he’s handed-down one contradictory, problem-inducing edict after another (An earlier one was that we could only take on as much fuel as we had when we came on charter, which is about 6,000 gallons less than we typically bring to the field. The field bosses weren’t too happy with that one.).

I get the sense this guy is ex-military. Also that he’s about to be ex-where-he-is-now. 

I’m out here to do a job and support my family. And, if feedback from the customer and our company is to be believed, I do a good job. I’m certainly not here to be insulted, browbeaten or talked to like I’m the Army’s newest basic trainee.

I’m confrontation-adverse in general, so the whole episode fell on the unhappy/tiresome end of the human interaction spectrum.

We finally embarked our passengers at around 0600, got clearance from traffic, and headed downstream to the Gulf.

Along the way I encountered some patchy fog, but didn’t begin worrying about it until visibility dropped to less than a quarter mile. 

When I couldn’t see the stern of the boat or the next set of markers, I sent my deckhand to wake-up the senior captain.

“What should I do now?” I asked.

“Hell, you need to turn around and head back to the dock,” he replied. And then, after ascertaining our position – very nearly out of the river: “Or maybe push up on the mud.”

Since we were just off a point that I figured had a pretty steep bank, I opted for the latter, and there we sat for most of the next hour, broadcasting security calls and watching a diffuse sun rise as Saturday’s fishermen materialized out of the fog and zoomed past us.

Our company has a “Zero Visibility” policy, which is vaguely enough worded that I’m not certain if it prohibits running in zero visibility or if it just gives captains the discretion to not run in zero visibility. 

I’m also not certain if zero visibility means I can’t see anything past 100 feet, past the bow, or past the windshield.

I already knew that one of our captains typically sits-out the fog, and another will happily run through it (especially if it’s crew change day and our destination is the dock).

Anyhow, conundrum solved by asking a question, and I learned a few things, too.

The rest of the trip out was a slog, kind of like running with a fire hose on the windshield the entire time. 

The design of this particular boat, with a fo’c’s’l bow, gives it more interior volume and more clear deck and – possibly – an easier ride, but it also makes it extremely wet.

Week before last a captain from another boat called me on the radio and asked if I still needed a periscope to run the boat. 

Turned out he had trained on an identical hull, and remembered well the constant deluge. I told him that if our windshield wiper ever went out, that would be a no-sail.

The truth of that statement became evident towards the end of my watch when a utility boat materialized off my port bow. A quick check of the AIS showed a closest point of approach of 0.13 mile. I called the boat and asked if he intended to hold his course and speed.

“Sure, cap. I ain’t gonna bother you none,” was the reply.

About a minute later, probably due to a course correction by one or both of us, the CPA had dropped to 0.00, and my  Mk I range-finding devices (eyeballs) agreed that a collision was imminent.

I called again, and informed the other boat that the CPA was now showing zero, and that I would alter course to port to pass behind him.

Thing is, that was his job, as the burdened or give-way vessel. Until he didn’t do it, when it became my job.

Reading up on the practical assessments for some of the STCW endorsements required for my next license, I saw that one of the standards (I think it was for Radar Observer Unlimited) is to maintain a CPA of three miles with other vessels.

Given the number of boats in our field, that’s not practical. 

But given all the open water out here there’s also no reason anyone should get as close to anyone else they don’t have business with as that utility boat did to me.