How a big, well-run, high-tech race boat, can go aground... almost

In light of all the speculation about how Team Vestas Wind could go aground by error, I would like to offer one distantly related scenario that helps remind us of our fallibility and the fate of circumstance. This was on a race boat having left Seattle on the way to Hawaii on a delivery to a race there. It was in fact a bigger boat than the VOR boats, and the skipper and several of the crew were as qualified as many VOR sailors. It had all the latest technology of the mid 90s.

We had rounded Pt. Wilson after dark under power, and had about 70 miles to reach the ocean in the Strait of Juan de Fuca. I had set way points for the route out, which was very basic. We travel along in the inshore zone, just out of the shipping lanes, facing inbound traffic on our right. Then I crawled into the bunk to get some rest so I would be fresh when we reached the ocean, which often has much converging traffic and usually new current and wind to deal with. Unfortunately (as it turned out) it was a beautiful, clear night, in perfect conditions, on an easy route, with nothing to worry about.

Sometimes it is hard to go to sleep early, so there was tossing and turning, in and out of sleep. But from my bunk I could hear conversation in the cockpit very clearly. Somewhere in the half sleep I over heard someone say “I didn't realize Smith Island Light would be so bright from here,” which bounced around in the mind for a few moments before i realized Smith Island Light is actually not bright from where we are at all!

I scurried on deck to learn that the crew were looking at Dungeness Light, essentially right next to us. We were inside of Dungeness Spit headed for the beach. There were just minutes to spin around and head back out.

So now we get to say just what we read in the news today: How could this happen with such a trained crew on such a high tech boat? In this case, the base cause was the regular navigator had sat down at some point earlier with good intentions to review the waypoints, and to make a personal preference change to let the waypoints automatically advance to the next when within some set range. Although I strongly disagree with that approach (I think they should always be advanced manually) that was not the cause. Some how in this process the crucial waypoint WP33 got deleted or skipped in the active route. We were essentially headed from WP32 to WP34 on a straight line.

But now we have to fold in all the special circumstances that let this type of error get by without being caught. Like many of the VOR boats we had an international crew, with some of the best sailors from around the world, and more to the point like many big boats with a crew of 9 to 11, most of the crew was not involved with the navigation at all. They assume this is a matter taken care of by 2 or 3 other members of the team, and they concentrate on their specialties. Of this crew we had several local folks who had been this route many times and would never have made this error, regardless of waypoints. But you can get at times combinations on watch or at the change of watch that might not include local knowledge. I do not recall these details, but at least one person on deck knew the light, but they might have just come on watch. In any event, that is what happened.

Our target was a gently sloping sand beach, so chances are we would not have suffered serious damage, but a grounding there could have caused enough damage to cause us to miss the race, and cost all the investment of time and money that went into the preparation. The incident had been out of my mind for many years, but this recent grounding brought back the memory quickly.

So one answer to how such things happen is this: one fundamental error that would normally be caught, does not get caught, because of a series of peripheral factors that sadly come together at the same time. There is sometimes a fine line between bad judgement and bad luck.

And what prevents such things? The answer is the Navigation Rules. We think of them as preventing collisions between vessels, but they are also intended to prevent hitting other objects or running aground. See notes in this definition of allision. As with collisions, every such incident with a functioning vessel involves the violation of at least one of the Navigation Rules. 

The key here is Rule 5 on Proper Look out. The rule includes several requirements of proper lookout, but no where near all of them. These others have been established in a number of court cases, which include such obvious ones as must be able to speak the same language as the helm and have some means to communicate with them. Another is they should have no other duties at the time. An always crucial one is they must know how to keep a watch, that is, what to watch out for.

With a group of folks on deck on a beautiful clear night, we in effect did not have any one on watch. This can be resolved by simply assigning that duty to one of the individuals, and even rotate the job on a long watch. It is also incumbent on the navigator to alert the watch to any specific hazard in the area to look out for.  And all of this is as important in clear beautiful conditions as it is in the worse conditions.  (There are more collisions in clear weather than in fog.)

Our situation might not have been that much different from what took place on the Vestus Wind. I recall a remarkable video of the incident just before the grounding where we can overhear the crew conversations. There were several folks on deck, and one of them said in a calm conversational tone, "Do you hear those breakers?" and an answer something like, "Yes, that's strange."

Scatterometer Winds

Index to Starpath articles on ASCAT.

We have set up a convenient way to look at scatterometer winds over the Rolex Sydney-Hobart Yacht Race course and the Transpac Yacht Race  course that will automatically update on each view.

Unfortunately, the multiple panels of data available meet in the center of the race course, so we had to combine multiple images... otherwise you could just look at the source data we use at the Ocean Surface Wind Team web site.  These data are originally analyzed at the  Royal Netherlands Meteorological Institute (KMNI), who have a different and sometimes preferred presentation (but not amendable to automatic reproduction... nor legal.)

Please have look at compilations we have made. We show ASCAT A and B, both ascending and descending, as well as the WindSat data, and the brand new Rapid SCAT data from the International Space Station.

Sydney-Hobart scattterometer winds

Transpac scatterometer winds

These are large images that you can drag around for best viewing.

In preparing this, we realized we needed a bit more instruction on how to figure valid times.  So here are some notes on this, but you can also download a pdf of the information below, which is just captured from that document.

See also Predicting Times of ASCAT Passes and Tactical use of Scatterometer Data.

.... or if you want to see the other end of the wind pole, ie not what it is doing now, but what it has done in the past, then see our discussion of the Sydney-Hobart Climatic Winds or Transpac Climatic Winds (coming soon). If you do not know what COGOW stands for, then it is even more important to check these links.

Archive of Past Articles

Taylor 1328PJ Sling Psychrometer — a Review

Relative humidity (RH) is a tricky measurement, primarily because it is so sensitive to the air temperature. One of the most basic measurements of RH is also one of the least expensive, namely a sling psychrometer. It has two identical thermometers one that remains dry (dry bulb) and the other covered by a clean cotton wick that is made wet with clean fresh water.  Both are mounted on a swivel that can be swung about for the purpose of increasing the rate of evaporation of water on the wick.

Since the process of evaporation takes energy it cools the water, wick, and the thermometer inside it as the water evaporates; the more the evaporation, the more the cooling.  But there is a limit, and that limit depends on the evaporation rate and that rate depends on the relative humidity of the air that is being evaporated into.  Thus the suppression of the wet bulb thermometer temperature compared to that of the dry bulb thermometer is a measure of the relative humidity of the air at the dry bulb air temperature.

We have tested several of the these Taylor units. They are well made and a nice compromise in price, size, and accuracy. The list price is about $180 these days, but generally you can find them notably less... and I have seen then on eBay called new for well under $100.

Range 20°F to 120°F
9" Permacolor™ filled thermometers
Temperature accuracy ± 0.2°
Folding swivel handle
Hard plastic protective case (about a 12 " wide)
6 replacement wicks

The instrument is used by wetting the clean wick with distilled water, then swirling it around for about 30 seconds or more (rather vigorously) and then reading the wet bulb and dry bulb temperatures. With these values you can look in tables (included with the device) to learn the dew point of the air and its relative humidity.  Or go to this link to find both RH and dew point from the two temperatures: www.starpath.com/calc.  Dew point is of more interest to navigators as it tells us how far we are from fog, whereas RH is of more interest to human comfort and how other things like violins and cigars interact with the atmosphere. Also for optimum espresso you have to change your grind number by 1 or 2 with RH changes between say 40 and 70.
 

By plotting dew point and temperature as a function of time you can often predict when fog will form. Accurate sling psychrometers like these can also be used to calibrate hygrometers that read the relative humidity directly on a dial. 

Here is a quick test of 4 Taylor units showing the dependability of the thermometers. The wet and dry bulb temperatures should be identical for all units on a given time when sitting side-by-side at rest, out of breezes, and on a uniform temperature base. Also keep in mind looking at the dial, that tenths of a degree must be estimated. These were read using a magnifying glass, being careful to avoid parallax errors, and being careful to not get so close to the thermometer that radiant heat from your own body does not change the reading, which is a real concern, because  the result is sensitive to tenths of a degree. Clearly they are all well within the specs given by Taylor. This is a crucial condition, because the accuracy of the humidity and dew point results are a direct computation from the temperature data. (Unit 4 was sold on Day 2.) 

 We only have these data at this temperature, but from this the instruments look good, and we have used our in-house model for several years.

A few related, random notes:

(1) There are devices like this that have reservoirs for the wick water and fans that blow on the dial (ie do not have to swing them) and some have even more accurate thermometers.  These are called Assmann aspiration psychrometers. Good ones cost $1000 to $1500.  These units can get RH to about 2%.

(2) RH can be measured directly, either electronically or mechanically (based on the fact that how much human hair stretches depends on the RH). 

(3) Electronic units that read RH directly and cost less than $100 or so, probably do not work.... ie compare 5 or 6 side by side and they will differ by 20 to 40%.  Even ones that cost $1,000 have to be calibrated every year or so.

(3) Hair hygrometers can be human hair (works all temperatures) or synthetic hair, works above freezing.  The Fischer Precision Instrument Company that is famous for high quality barometers receives the same high esteem worldwide for their hair hygrometers.  Synthetic hair takes less maintenance. Always get a matching thermometer to sit beside it as you must know both numbers to do anything with the results.  ie, to say the RH is 40% does not tell you much about the conditions of your atmosphere without knowing what temperature that was.  Fisher hair hygrometers (model 122.01) cost about $60 and yield about 3-5% accuracy... all such instruments must be calibrated at some point. Matching thermometer (model 117.01) costs about $40.

(5) I must also add that we have not tested less expensive sling psychrometers. It could be that some that cost much less will also do the job.  They key issue is are the thermometers identical and how accurate can you read them.  In principle you could make your own from two thermometers and just blow a fan on them.  We have done that with our Taylor and that works fine.... if not better than slinging it around. The wicks are easy to find online. You might call that one a half-Assmann model.

In short, a device like the Taylor model above is a good solution to many needs for accurate RH... or as a way to calibrate a good hair hygrometer.