Tag Archives: water temperature

Limiting Factors in Marathon Swimming – Part 2 – Environmental Factors

In Part One I covered the physiological limiting factors in marathon swimming.

The various environmental aspects of a swim are not insignificant. They are especially important in that they all lay outside the swimmer’s control and often even outside the control of the support crew.

Water Temperature

Thermometer
Thermometer

This is generally a known factor prior to a swim. Swims are either cool or cold water like the English and North Channels or warm water swims like Maui, Rottnest, Manhattan or Chloe Maccardels’ upcoming Cuba to Florida attempt. A few fall into an intermediate category defined more by the swimmer’s experience, such as the Catalina and Gibraltar Channels. Sudden changes in temperature are rare in marathon swimming and where they are possible they are also understood; such as South Africa’s west coast which is prone to sudden wide water temperature changes, and the California coast where the sudden transition from very deep water to a shallower continental shelf very close to the  mainland can cause cold water upwelling at the end of a marathon swim. Air temperature is obviously much more variable and a condition of the weather but extremes of air temperature are not usual during a swim. A five degree Celsius differential can be significant for a swimmer if such a drop is also accompanied with a breeze or wind which can sap the swimmer of body heat.

Jellyfish

Lion's Mane jellyfish
Lion’s Mane jellyfish

The recent and future attempts at a distance and time records by necessity are held in warmer waters such as Cuba to Florida.  These water are home to jellyfish with debilitating stings such as Box Jellyfish. While the cold waters  of the North and English Channels are home to Lion’s Mane and Portuguese Man O’War’s endurance records are less likely and jellyfish stings in the English Channel are rarely more than intermittent, though the North Channel (the Mouth of Hell) can have miles of Lion’s Mane blooms, part of what makes it the ultimate channel swim. Attempts to swim in these waters divide swimmers in two ways: whether attempts should be made in locations not considered possible without additional protection or exceptions to the usual rules, and if so are jellyfish protection suits acceptable or the thin edge of a wedge that will inevitably lead to more overt (or hidden) performance enhancing suits? (See Evan’s analysis of his survey of marathon swimmers for an excellent overview of the contradictions of divisions and unity in the community).

Sharks

The Man In The Grey Suit is a subject of great concern (and discussion) for distance swimmers. Not of any real concern here in the north-eastern Atlantic, they are a greater hazard in the warmer waters elsewhere, particularly California, the Caribbean, Hawaii, South Africa and Australia. The Cook Strait Channel swim in New Zealand is unique in having a shark evacuation rule. Shark cages have been used for marathon swims in the Caribbean and South Africa at least. Shark cages are however considered swim assistance as they increase the swimmer’s speed through eddy current drag. Other possible control methods include electronic shark repellents (whose effectiveness is not entirely assured or quantified), armed boat crew or armed or otherwise scuba diver outriders.

Tides

These are amongst  the most variable of environmental factors and therefore potentially also the most limiting. Because swimmers move slowly relative to even a sailing boat, we are vulnerable to slight deviations, miscalculations or just insufficient data, the most likely cause. Even in such a well-travelled and mapped location as the English Channel, especially for swimming, pilots will occasionally speak of tides arriving early or late or with a difference force than expected. Tidal currents are understood at a larger scale, hundred of years of navigation have mapped the seas for craft, not for swimmers. Tides act in a similar chaotic way to a weather system, which means that small deviations will always creep in. The only way to improve accuracy of prediction is to improve the data, and this is not practically possible or even desired for small tidal variations. As swims occur in less well-known or new locations, the likelihood of discovering unknown local variations outside marine charts increases. Half a knot current, barely detectable to a boat, is enough to deviate a swim over hours from a projected or necessary course.

Global tides
Global tides

Crew and boat

Any English Channel pilot will confirm that one of the most likely causes of unsuccessful Channel swims is poor selection of support crew. The most likely cause is mal-du-mer, seasickness. For some people seasickness is a completely debilitating ailment that can sap all willpower and strength and there is no way to know whom it will strike. The solution of course is to have experienced crew. Even this can fail because people experienced on powered craft will be at the mercy of the choppy water amplified on an almost stationary craft. Other crew issues can also arise, whether accidents or other illness. Anyone who hasn’t been on a rocking boat looking down on a swimmer is unlikely to understand! And not unknown are mechanical problems on the pilot-boat. Most pilots are by necessity practical mechanics able to address problems as they arise, but not all problems can be fixed with a wrench and hammer while rocking about on the sea.

Channel boat The Viking Princess
Channel boat The Viking Princess out of the water

Weather

Weather changes are the bane of English and North Channel swimmers particularly. Other Channels like Tsugaru and Gibraltar and Cook are also subject to constantly variable and unpredictable weather patterns. If you are used to the predictable weather of the west US coast, with morning offshore and afternoon onshore breezes, knowing your swim will almost certainly take place with a 48 window, the difficulty of allocating two weeks or even long (like the North Channel) and still being completely unsure of getting in the water is shocking. Weather constraints obviously ran the full gamut. In the North, English and Gibraltar channels the main concern is wind (and its effect on the seas). Fog can also be a problem with 2012′s Channel season infamously seeing three solos on one day abandoned within a kilometre of France for the first time in 137 years. I’ve warned previously that fog may be the most dangerous weather condition for swimmers. In warmer humid climes like Round Manhattan, and the Caribbean, lightning storms are a serious cause for worry, a swimmer or boat caught exposed out on the water is in real danger. Having to wait for or even postpone a swim is something many marathon swimmers have undergone and the mental pressure this brings is often not inconsiderable, which I will discuss further in the next and final part.

Coming in part three, Psychological Factors.

 

Is the water too cold to swim?

This article is, once again, a variation of the most popular question here: “What temperature of water is too cold to swim in”?, which I’ve written about before.

Thermometer
Image by Ben+Sam via Flickr

The temperature at the Guillamene last Sunday week (October 16th, 2011) was about 13° Celsius (55° F). That’s far warmer than what most people will imagine, not far off the highest normal summer water temperature (about 15° to 16°, excluding unusual warmer pockets or days) for Ireland’s South Coast. And by the end of last week it was down to about 11.5° Celsius.

The weather is changing though, autumn and early winter storms have shown up and the water is rough most days. There’s been fog that has lasted for days,and the days of grey skies and continuous rain. Days and nights are cooler (though given the crap summer, again, in Ireland, that’s not much of a real change, only about 4° to 6° Celsius change for now.) Surely, many people will say, the water is cold!

Annual mean sea surface temperature from the W...
Image via Wikipedia

Occasional swimmers have changed to wetsuits weeks back. But experienced swimmers are still, should they desire, putting in two or three hours without wetsuits, (if they haven’t gone back to pool training or like me, have slackened off for the end of season).

So this is a critical time for those considering a big swim for next year, or wanting to improve their open water ability. Time when you should be asking yourself:

How much more do I really want to able to do?

You can stop now, leave the sea, and just do pool training. or you can retain your sea swimming. You can use a wetsuit, and get used to the sea in winter. Or you can stay in skin, and discover that for maybe another three or four weeks, it’s not that cold.

You can approach this as a multi-year project, this winter just keeping swimming regularly in rubber, maybe dumping the neoprene for a few minutes of skin only here and there, and then next year going a bit further before donning it. The only mistake is to expect to be able to handle cold without doing any work.

An important thing to remember now is Rate of Change, rather than deciding what temperature is your cutoff (because without experience you won;t know anyway). The water temperature will drop soon, (I’ll let you know when The Big Drop happens, it could be as soon as three weeks or could be as long as six or seven). The Big Drop is when the water temperature goes below ten degrees Celsius 9 50° Fahrenheit). Yes, yes … don’t tell you can even get that low, I can hear you from here.

Last year the coldest day was late November, after the coldest spell Ireland had in something like 60 years. And it recovered afterwards. By Christmas the temperature was back to normal for that time of year, at about nine degrees (48° F.).

So now is the time and chance to do address two big issues:

1: Your perception of the world around you, especially the sea.

2: Your perception of yourself, and your limits and capabilities.

I know what some of you are thinking: but this guys is already experienced at cold, and I couldn’t do it. Nonsense. Anyone can, as I keep repeating, you just have to decide whether you want to or not.

There’s already lots of writing about cold on this site, see the top menu bar up there? ^^^

Go beyond your limits. Go on. Do it. I’ll meet you at the Guillamene.

P.S. As I was wondering what images to add to this, I really wished I had one of a swimmer with a meat thermometer stuck in them. But, apart from the pictures of Gábor, this is a Safe For Work site.