Sunday, July 31, 2016

Understanding wave height measurements & concepts

There is a tremendous amount of misinformation, guesstimating and wild wishful thinking involved in wave heights. I thought this article which I have adapted from one the Bureau of Meteorology in Australia put out would be useful. Anyone who visits / uses the beach / ocean needs to understand this concept and the related terminology in use around wave / swell predictions.

A lack of understanding costs the lives of many rock fishermen and boaties every year. It is also the cause of many rescues of swimmers from flash rips. When these large waves hit the beach the massive volume of water has to find its way back out to sea and can / does very easily drag unwary swimmers with it. 
Ruling the waves: How a simple wave height concept can help you judge the size of the sea

Predicting the size of the wind-generated waves that roll in from the sea around Australia is not as hard as you might think—especially if you understand the concept of ‘significant wave height’.

While down at the beach or out on the water you will experience a wide range of wave heights during your activity, and occasionally a genuine ‘big one’, the fabled "rogue", "bomb" or "wave of the day". However wonderful a prospect they are to surfers, big waves can pose a serious danger to boaters and fishermen—particularly when they arrive at reefs, bar crossings and deep-water coastlines, where the first indication of a wave’s true size can be as it breaks on the rocks where you’re standing. These are the rock fisher killers and the reason rock fishing is Australia's most dangerous sport. They are also the cause of many boat capsizes and sinkings due to the simple face that the anchor chain / rope was not long enough to accommodate the big one.
The size and behavior of waves are determined by a range of factors, from the direction of the swell to the speed of the tide, prevailing ocean currents, the depth of the water, the shape of the seafloor, the presence of reefs and sandbanks, even the temperature of the ocean. Ever wondered why on a very large beach all the surfers are crowded into the one or two spots? Well know you know, they have located "The Bank" and are using it to get a good ride. The surfers will also show you where the rips are. They use them as an ocean elevator to get a free ride back out the back for their next ride...
However, there is one factor that rules the size of the waves more than any other—the wind. Waves are caused by wind blowing over the surface of the ocean and transferring energy from the atmosphere to the water. The height of waves is determined by the speed of the wind, how long it blows, and crucially the ‘fetch’—the distance that the wind blows in a single direction over the water.
Naturally, bigger waves result from conditions that cause strong winds to blow for a sustained period over a large expanse of ocean. The resulting waves can travel for hundreds or even thousands of kilometers, smaller waves being absorbed by larger ones, faster waves overtaking slower—gradually growing and arranging themselves into the regular ‘sets’ so familiar to lifeguards, surfers and paddle-boarders. Understanding this along with wave periods, assists the lifeguard to pick the best time and location to head out for a rescue.
The result of these interactions is that it is normal to experience a wide range of wave heights when on the water.

A universal convention to measure wave height

Utilising the standard international convention, the Bureau uses the concept of ‘significant wave height’ to notify ocean-goers of the size of swell and wind waves (or ‘sea waves’) in its coastal forecasts. Significant wave height is defined as the average wave height, from trough to crest, of the highest one-third of the waves.
Devised by oceanographer Walter Munk during World War II, the significant wave height provides an estimation of wave heights recorded by a trained observer from a fixed point at sea. As the following graph shows, a sailor or surfer will experience a typical ‘wave spectrum’ during their activity, containing a low number of small waves (at the bottom) and a low number of very large waves (at the top). The greatest number of waves is indicated by the widest area of the spectrum curve.
The highest one-third of waves is highlighted in dark blue in the graph below, and the average height of waves in this group is the significant wave height:
A wave twice the height of a 'significant wave' is likely to occur 3 times in 24 hours (1 in every 3000 waves)
Significant wave height
This statistical concept can be used to estimate several parameters of the waves in a specific forecast. The highest ten per cent of the waves are roughly equal to 1.3 times the significant wave height, and the likely maximum wave height will be roughly double the significant height. So, if you are going rock fishing or anchoring your boat near a reef etc, remember it is not good enough to simply look at one or two waves and she will right mate.....it won't be, allow for the bombs or pay the ultimate sacrifice. No matter how good and how fast the lifeguards are, sometimes we will not be able to save you.

Expect double the height, three times a day

While the most common waves are lower than the significant wave height, it is statistically possible to encounter a wave that is much higher—especially if you are out in the water for a long time. It is estimated that approximately one in every 3000 waves will reach twice the height of the significant wave height—roughly equivalent to three times every 24 hours. As a reminder of this important safety concept, the Bureau includes a message that maximum waves may be twice the significant wave height in all marine forecasts.
It is normal for waves to vary in height from one to the next

Most frequent, 'significant' and maximum wave heights
When planning a voyage, mariners should not focus exclusively on the significant wave height in a forecast. It is equally important to recognise the concept of the wave spectrum, know the definition of significant wave height, and be able to determine the expected range of wave heights.
Much like the median house price guide in the real estate sector, the significant wave height is intended as an indicative guide that can help you gauge the range of wave sizes in a specific area. While sailors can use the figure to evaluate the safety of an open-water voyage, surfers may use it to rate the likelihood of at least one ‘big one’ arriving while they’re out in the surf. Rock fishers should also be aware of the dangers of the ‘big one’ washing them off the rocks.

Wave forecasts in Australia

Wave height information for seas and swells is included in the Bureau’s Coastal Waters and Local Waters forecasts, covering the Australian coastline and capital city waterways. These forecasts are also transmitted by marine radio (HF and VHF).
Maps and tables of swell and wind wave heights are also available on MetEye—the Bureau’s interactive weather-mapping tool—which allows mariners to ‘play the weather forwards’ over a specific stretch of water for the coming week.
More information on MetEye’s wind and wave features can be found in these recent articles:

More information

About marine weather services: Information on the Bureau’s marine forecasts and terminology.
Preparing for your trip: Boating tips from the Australia New Zealand Safe Boating Education Group.
Important note: Please be aware that wind gusts can be 40 percent stronger than the averages given in coastal forecasts, while maximum waves may be up to twice the significant wave height.

Friday, July 29, 2016

RIP Currents what you need to know to escape them


What You Need To  Know About Surviving Rip Currents.

Many hundreds (if not thousands) of people drown after being sucked out to sea in rips each year, what do you need to know in order to escape this menace?



riptide
Rip currents kill more beachgoers each year than any other threat. Time to learn how to fight them.    Photo:Todd Quackenbush/Unsplash
Conventional wisdom says that Rips flow seaward, out to deep water, so beach access signs across the world advise swimmers to paddle parallel to the beach in order to escape the them. The strong, sometimes unpredictable (flash rips) kill more beach goers each year than any other threat.
 
Rips can form on any beach, sometimes suddenly, there one minute, gone the next (flash rips), swimmers usually don’t know a rip’s present until they’re in its clutches and on the way out to sea (out the back).  The photo opposite shows yours truly with a team of Scarborough Lifeguards (including one of our all girl IRB crews Tenae & Sam) performing a mass rescue due to a flash rip. Photo courtesy of the SLSWA Lifesaver One helicopter.


Unfortunately rips can, to the untrained eye, appear to be the best place to swim. As the photo opposite shows, the waves are not breaking in the rip (as the water is deeper), the water looks flatter / calmer in the rip than the remainder of the beach around it.  Panicked victims caught by the rip often try to swim directly back to shore—against the powerful offshore flow. Swimmers familiar with rips might try swimming parallel (left of right along the shore line) to escape. in some cases however simply giving in and going with the flow is the best option. Relax, float and raise / wave one arm to attract the attention of Lifeguards as the girls in the photo below did.

A number of rips flow in large circles, from the shallows, out through the breakers and part way back again. A swimmer stuck in a circulating rip has no way of knowing which way the current is flowing. That means that by swimming parallel to the shore—something signs at nearly every popular beach in the country advise—the swimmer has a 50/50 chance of paddling against the deadly current. In this case, and I am talking circular rips, or, if you are in any doubt, simply float on your back, relax and raise an arm to attract the attention of the Lifeguards as the girls opposite did last summer off Scarborough Beach.
The U.S. Lifeguard Association estimates that in the USA nearly 100 people die in rip currents each year, and that lifeguards saved over 48,000 Americans from rips in 2015 alone. The typical victim struggles against the unrelenting pull, panics, and eventually succumbs to exhaustion. Rips can form on any beach with waves, in nearly any conditions. They occur when the water is pushed up onto the beach, by the surf or wind, flows back out to sea in narrow, concentrated channels and they can be anywhere from ten to 200 feet wide. To make matters worse, their outward course often dulls the breaking waves and creates the illusion of calmer waters for inexperienced beachgoers. Lifeguards call rips “drowning machines.” Within the City of Stirling rips are nearly always marked by "Dangerous Current" or "No Swimming" signs like the ones below. Please do us all a favour and stay well clear of these areas. If you are in any doubt, don't go out, ask the Lifeguards or Beach Inspectors for advise on the best place to swim.

Today, rips kill more Australians than bushfires, floods, cyclones, and sharks combined.
There’s not one single message that works on all beaches. Sometimes swim parallel is great, sometimes it doesn’t work. Same for floating.
Rips are a complex, dynamic hazard and the multitude of variables—swimming ability, current strength, circulation, wave size—make the threat nearly impossible to solve with one-size-fits-all advice. No single “escape strategy” is appropriate all the time. If you’re not a strong swimmer, stay afloat and signal for help; if you can swim, consider paddling parallel to the beach toward breaking waves—though be mindful of the potential circulating current.

The best advise I can give is ALWAYS, ALWAYS swim at a patrolled beach, preferably between the red & yellow flags. If you get caught by a rip, relay float with it and raise an arm to attract attention of the Lifeguards. Remember the worst case is, when the Rip fades out, and they ALWAYS DO, you will have to simply swim or body surf your way back to the beach!


Rips don't kill, inexperience and panic does! 

Don't be a statistic, stay calm, relax and you will eventually be able to make your way back to shore.

Friday, July 22, 2016

We are HIRING - Lifeguards wanted for 2016-17 summer

We are HIRING!

The City of Stirling has opened expressions of interest from ocean Lifeguards for the upcoming summer season 2016-17.

We are looking for a team of professional Lifeguards to assist our four full time Beach Inspectors keep everyone safe on our beaches this summer.

Our little team performs, on average, 500 surf rescues per season. we undertake approx 400 first aid treatments and perform something in the order of 7000 preventative actions.

The job entails protecting patrons on Brighton, Watermans and includes Scarborough and Trigg beaches, two of, if not the, most dangerous beaches in Perth.

The photo opposite shows yours truly with a team of Scarborough Lifeguards (including one of our all girl IRB crews Tenae & Sam) performing a mass rescue due to a flash rip. Photo courtesy of the SLSWA Lifesaver One helicopter.

In order to apply you will require the following:
  • A work permit / visa or the right to work in Australia (no sponsorships)
  • A Surf Lifesaving / APOLA or equivalent surf bronze medallion
  • A Surf Lifesaving / APOLA or equivalent surf Advance Resuscitation Certificate
  • A Surf Lifesaving / APOLA or equivalent surf IRB Drivers award
  • A Surf Lifesaving / APOLA or equivalent Senior First Aid Certificate
  • C Class motor vehicle drivers license (need to be 17 yrs + of age)
  • A national (Australian) Police Clearance
  • Complete a pool swim (50mtr pool) of 800mtr in less than 14 min
  • Complete a Tube rescue (in surf with patient 100+ mtrs off shore
  • Complete a board rescue (in surf with patient 200+ mtrs off shore)
  • Complete a Lifeguard mission (800m run + 400m ocean swim + 800m run + 400m ocean board paddle).

Not required but desirable are the following awards:

  • Analgesic Gases (Penthrane)
  • Spinal Management
  • RWC (Jetski) award
  • At least three years surf patrol and or Life guarding experience
 For further details / questions just drop me a line or comment below.


Expressions of interest to Mr John Snook


 APOLA = Australian Professional Ocean Lifeguard Association.

This job is not for the faint hearted, You will perform 30 - 40+ rescues during the season, sometimes on your own others with backup. Despite the best efforts of our dedicated team, tragedy does strike and you will need to have to deal with this.

Mistakes on these beaches cost lives. We are looking for the best of the best, if that is you, do us all a favor and apply now!



 

Drowning doesn't look like drowning


Drowning Doesn’t Look Like Drowning

  • drowning

    Drowning Doesn’t Look Like Drowning

    Drowning is not the violent, splashing, call for help that most people expect. Professional lifeguards are trained to recognise drowning with many years of experience they know exactly what to look for, when and where. Parents, guardians, siblings and friends on the other hand, have learned what drowning looks like by watching television. If you spend time on or near the water (hint: that’s all of us Aussies) then you should make sure that you and your crew know what to look for whenever people enter the water. Many drowning victims never make a sound. Drowning is almost always a deceptively quiet event. The waving, splashing, and yelling that dramatic conditioning (television) prepares us to look for, is rarely ever seen in real life.

    The Instinctive Drowning Response – so named by Francesco A. Pia, Ph.D., is what people do to avoid actual or perceived suffocation in the water. And it does not look like most people expect. There is very little splashing, no waving, and no yelling or calls for help of any kind. To get an idea of just how quiet and undramatic from the surface drowning can be, consider this: It is the number two cause of accidental death in children, age 15 and under in the USA (just behind vehicle accidents) – of the approximately 750 children who will drown next year in the USA about 375 of them will do so within 20 meters of a parent or other adult. In ten percent of those drownings, the adult will actually watch them do it, having no idea it is happening. In Australia almost 300 people drown each year at a cost to our Aussie ecconomy of $1 Billion annually. Drowning does not look like drowning – Dr. Pia, in an article in the Coast Guard’s On Scene Magazine, described the instinctive drowning response like this:
    1. Except in rare circumstances, drowning people are physiologically unable to call out for help. The respiratory system was designed for breathing. Speech is the secondary or overlaid function. Breathing must be fulfilled, before speech occurs.
    2. Drowning people’s mouths alternately sink below and reappear above the surface of the water. The mouths of drowning people are not above the surface of the water long enough for them to exhale, inhale, and call out for help. When the drowning people’s mouths are above the surface, they exhale and inhale quickly as their mouths start to sink below the surface of the water.
    3. Drowning people cannot wave for help. Nature instinctively forces them to extend their arms laterally and press down on the water’s surface. Pressing down on the surface of the water, permits drowning people to leverage their bodies so they can lift their mouths out of the water to breathe.
    4. Throughout the Instinctive Drowning Response, drowning people cannot voluntarily control their arm movements. Physiologically, drowning people who are struggling on the surface of the water cannot stop drowning and perform voluntary movements such as waving for help, moving toward a rescuer, or reaching out for a piece of rescue equipment (Ed something that should be noted by the supporters and developers of drones dropping rescue rings etc)
    5. From beginning to end of the Instinctive Drowning Response people’s bodies remain upright in the water, with no evidence of a supporting kick. Unless rescued by a trained lifeguard, these drowning people can only struggle on the surface of the water from 20 to 60 seconds before submersion occurs.
    (Source: On Scene Magazine: Fall 2006 (page 14))
    This doesn’t mean that a person that is yelling for help and thrashing isn’t in real trouble – they are experiencing aquatic distress. Not always present before the instinctive drowning response, aquatic distress doesn’t last long – but unlike true drowning, these victims can still assist in their own rescue. They can grab lifelines, throw rings, etc.
    Look for these other signs of drowning when persons are in the water:
    • Head low in the water, mouth at water level
    • Head tilted back with mouth open
    • Eyes glassy and empty, unable to focus
    • Eyes closed
    • Hair over forehead or eyes
    • Not using legs – Vertical
    • Hyperventilating or gasping
    • Trying to swim in a particular direction but not making headway (caught in a rip)
    • Trying to roll over on the back
    • Appear to be climbing an invisible ladder.
    • Spending too much time in the surf impact zone being smashed by the waves not making any real attempt to avoid or minimise the wave impacts
    • Some will disguard their surf / boggie boards and try to swim back to shore
    • Don't appear to be in control of their actions
    • Swimming / floating in areas where they shouldn't be (rips / impact zone etc)
    So if a crew member falls overboard and everything looks OK – don’t be too sure. Sometimes the most common indication that someone is drowning is that they don’t look like they’re drowning. They may just look like they are treading water and looking up at the deck. One way to be sure? Ask them, “Are you alright?” If they can answer at all – they probably are. If they return a blank stare, you may have less than 30 seconds to get to them. And parents – children playing in the water make noise. When they get quiet, you get to them and find out why.
    If at all possible, never attempt a rescue unaided. Always try to take a floatation device with you.