Just general surfing stuff

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steve shearer
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Re: Just general surfing stuff

Post by steve shearer » Mon Aug 13, 2018 4:46 pm

btw, I think that 8000kj call for next Mon is a classic case of a model spack out.

my call: windy, pushy, 6ft S swell.
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Cranked
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Re: Just general surfing stuff

Post by Cranked » Mon Aug 13, 2018 5:01 pm

Nick Carroll wrote:
Mon Aug 13, 2018 12:45 pm
nah it's fine, 2000 calories? most of us would walk that off.

it is actually the thing that's been troubling me about all this fcuken Kilojoule talk though. What does it mean? Does it mean how much energy passes a certain point in a certain time? Does it mean the energy contained in some portion of a swell or wave as it travels or breaks over a certain amount of time?

Like kilojoule when applied to foodstuff is pretty clear, x amount of the foodstuff contains a potential energy availability of x kilojoules.

So what's the x in this? Swell trains aren't like that.
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object. Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.

Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature.

As the Russian physicist Lev Okun said, “The more basic is a physical notion, the more difficult to define it in words.” For energy, the best we can do is say it’s the capacity to cause movement.
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

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Cranked
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Re: Just general surfing stuff

Post by Cranked » Mon Aug 13, 2018 5:22 pm

Hatchnam wrote:
Mon Aug 13, 2018 4:41 pm
Am I getting the hang of it..?
Cranked wrote:
Mon Aug 13, 2018 4:02 pm
200kJ - barely breaking, get out your log = 1 foot
500kJ - surfable, use your twinny = 2 foot
1000kJ - have fun on your small wave board = 3 foot
1500kJ - good overhead surf = 4 foot
2000kJ - really good head and a half, some doubles = 4-6 foot
2500kJ - consistently overhead, frequent doubles = 5-6 foot
3000kL - lots of doubles, some bigger = 6-8 foot
3500kJ - only the good surfers are out = 8-10 foot
4000kJ - I'm just watching = 10-12 foot
5000kJ - a lot more are watching, guys with guns are getting most of the waves = 12 foot plus
8000kJ - 9' gun = 15 foot
10,000kJ - 10' gun or a ski = 18 foot
15,000kj - skis only = 20 foot
Yeah pretty good Hatchy.
Apart from the usual real feet/surfer feet as a source for confusion, my concern is that your scale is non linear and does not reflect the actual wave energy. The kJs have gone up 75 fold but your measurements units have gone up by a factor of only 20. Non linear measurement units are not generally a good thing.
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

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Re: Just general surfing stuff

Post by Nick Carroll » Mon Aug 13, 2018 6:39 pm

ctd wrote:
Mon Aug 13, 2018 3:58 pm
It’s pretty obvious. A joule is equal to the energy transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N⋅m).

Or in other words kg * m2 / s2; where kg is the kilogram, m is the metre, s is the second

So 1000 of those

(Of course, a wave of 4ft and period of 12 seconds means nothing out of context either. It’s only because you instinctively know what that translates to in the surf relative, to other sizes and periods, that it means anything. I just measure in increments of fear)
No it's not at all obvious. A swell event spreads out across thousands of nautical miles. It strikes here and it strikes there. There's radial spread which varies enormously from swell to swell. A single swell event can span almost the entire Pacific basin. It may also focus on 200 kilometres of coastline.

Again: what does it mean? Where is that 8000 kilojoules of energy likely to be expended? Here? Over there? In what timespan? For how long?

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Re: Just general surfing stuff

Post by Beanpole » Mon Aug 13, 2018 6:45 pm

Cranked wrote:
Mon Aug 13, 2018 4:02 pm
200kJ - barely breaking, get out your log
500kJ - surfable, use your twinny
1000kJ - have fun on your small wave board
1500kJ - good overhead surf
2000kJ - really good head and a half, some doubles
2500kJ - consistently overhead, frequent doubles
3000kL - lots of doubles, some bigger
3500kJ - only the good surfers are out
4000kJ - I'm just watching
5000kJ - a lot more are watching, guys with guns are getting most of the waves
8000kJ - 9' gun
10,000kJ - 10' gun or a ski
15,000kj - skis only
3-)

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Legion
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Re: Just general surfing stuff

Post by Legion » Mon Aug 13, 2018 7:14 pm

Nick can you have a word to that Kaipo kook. I had the webcast on today and he actually said someone who got a barrel visited their spirit cave

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Re: Just general surfing stuff

Post by BA » Mon Aug 13, 2018 7:15 pm

Holy shit. :roll:

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Re: Just general surfing stuff

Post by steve shearer » Mon Aug 13, 2018 7:19 pm

that was Chris cote.
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Re: Just general surfing stuff

Post by BA » Mon Aug 13, 2018 7:20 pm

Either way, someone needs a punch in the throat.

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Re: Just general surfing stuff

Post by Nick Carroll » Mon Aug 13, 2018 7:27 pm

Ah yes the spirit cave. So fleeting! So private! Except when you’re in a heat and 1.6k people are watching.

Man someone oughta take JW out and slap him.

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Re: Just general surfing stuff

Post by steve shearer » Mon Aug 13, 2018 7:37 pm

I want Nightclub Dwight dead in his grave I want the nice-nice up in blazes

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Re: Just general surfing stuff

Post by Cranked » Mon Aug 13, 2018 7:54 pm

Nick Carroll wrote:
Mon Aug 13, 2018 6:39 pm
ctd wrote:
Mon Aug 13, 2018 3:58 pm
It’s pretty obvious. A joule is equal to the energy transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N⋅m).

Or in other words kg * m2 / s2; where kg is the kilogram, m is the metre, s is the second

So 1000 of those

(Of course, a wave of 4ft and period of 12 seconds means nothing out of context either. It’s only because you instinctively know what that translates to in the surf relative, to other sizes and periods, that it means anything. I just measure in increments of fear)
No it's not at all obvious. A swell event spreads out across thousands of nautical miles. It strikes here and it strikes there. There's radial spread which varies enormously from swell to swell. A single swell event can span almost the entire Pacific basin. It may also focus on 200 kilometres of coastline.

Again: what does it mean? Where is that 8000 kilojoules of energy likely to be expended? Here? Over there? In what timespan? For how long?
I'll do a really rough calculation

The formula for Kinetic energy in joules is J = (mass in kg x (velocity in meters/second) squared)/2

One litre of water weighs one kg

An oceans wave with a wave length of 100m has will have a wave speed of 12 m/sec.

If we take a section of that wave to be just 100m long and one meter wide it will contain at least 100 cubic meters of water. One cubic meter of water contains 1000 liters, so thats 100,000 liters of water moving at 13m/s

So the energy for that section of one meter of the wave is (100,000kg x 13m/s x 13m/s)/2 = 8.5 million joules The wave energy is conserved, so each 1 meter wide section of that wave when it breaks will be delivering at least 8.5 million joules

I've probably fcuked up somewhere. Feel free to point out where.
Last edited by Cranked on Tue Aug 14, 2018 5:31 am, edited 2 times in total.
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Re: Just general surfing stuff

Post by Beanpole » Mon Aug 13, 2018 8:07 pm

Sounds good to me.

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Re: Just general surfing stuff

Post by Cranked » Mon Aug 13, 2018 8:29 pm

Can someone please do a similar calculation for MM throwing a good haymaker punch.
This is more the sort of thing that would fix the concept of kinetic energy in nicks mind
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Re: Just general surfing stuff

Post by godsavethequeen » Tue Aug 14, 2018 4:04 am

How’s that comparison data coming along steve? Anything yet?

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steve shearer
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Re: Just general surfing stuff

Post by steve shearer » Tue Aug 14, 2018 4:40 am

Have you not been reading?

Is west east in Wales?
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Re: Just general surfing stuff

Post by offshore1 » Tue Aug 14, 2018 4:49 am

Cranked wrote:
Mon Aug 13, 2018 7:54 pm
Nick Carroll wrote:
Mon Aug 13, 2018 6:39 pm
ctd wrote:
Mon Aug 13, 2018 3:58 pm
It’s pretty obvious. A joule is equal to the energy transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N⋅m).

Or in other words kg * m2 / s2; where kg is the kilogram, m is the metre, s is the second

So 1000 of those

(Of course, a wave of 4ft and period of 12 seconds means nothing out of context either. It’s only because you instinctively know what that translates to in the surf relative, to other sizes and periods, that it means anything. I just measure in increments of fear)
No it's not at all obvious. A swell event spreads out across thousands of nautical miles. It strikes here and it strikes there. There's radial spread which varies enormously from swell to swell. A single swell event can span almost the entire Pacific basin. It may also focus on 200 kilometres of coastline.

Again: what does it mean? Where is that 8000 kilojoules of energy likely to be expended? Here? Over there? In what timespan? For how long?
I'll do a really rough calculation

The formula for Kinetic energy in joules is J = (mass in kg x (velocity in meters/second) squared)/2

One litre of water weighs one kg

An oceans wave with a wave length of 100m has will have a wave speed of 12 m/sec.

If we take a section of that wave to be just 100m long and one meter wide it will contain at least 100 cubic meters of water. One cubic meter of water contains 1000 liters, so thats 100,000 liters of water moving at 13m/s

So the for that section one meter of the wave is (100,000kg x 13m/s x 13m/s)/2 = 8.5 million joules The wave energy is conserved, so each 1 meter wide section of that wave when it breaks will be delivering at least 8.5 million joules

I've probably fcuked up somewhere. Feel free to point out where.
So how big a wave would that be cranky, in Iggy feet.

Edit: reading back I'm reckoning 15+?
Last edited by offshore1 on Tue Aug 14, 2018 5:49 am, edited 1 time in total.

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Re: Just general surfing stuff

Post by godsavethequeen » Tue Aug 14, 2018 4:59 am

Magic seaweed are a bunch of spastics. That’s beyond dispute. What is still up on the air is the value and accuracy of their data

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