Just general surfing stuff

[steve shearer]

Cranked 8470 kj forecast for Lennox head next Monday.

any idea what that means?

[tootr]

It means if you eat more than that daily for an extended period of time you’ll get fat.

[Nick Carroll]

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.

[steve shearer]

It's a good question.

Cranked seems to have calibrated it in his mind as a measure of the maximum theoretical limit he feels comfortable surfing.

After over a month of checking surf forecast daily I haven't been able to peg it onto any kind of actual reality out in the surf zone.

[Cranked]

Cranked 8470 kj forecast for Lennox head next Monday.

any idea what that means?

Some set waves with 20' faces. I probably wouldn't go out. If I did I would be nervously and constantly scanning the horizon and paddling for it whenever I saw a distant shadow that might be the one hour set wave on its way.

[ctd]

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)

[Cranked]

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

[BA]

[Cranked]

No. Around Perth the offshore reef blocks most of the swell but the surf forecasts don't take this into account. I usually just convert the metres on the forecasts to feet, that is if the swell is 3m I'll assume its 3' faces.

Because of refraction around the reef gaps even a 3m swell is pretty much destroyed, especially as this phenomena increases with swell height. Consquently best swell size is under 2m as the smaller swells pass over the reef without too much interference.

The reef is the old drowned coastline, so its really consistent from about Dunsborough to Carnarvon. With a few gaps though.

I don't go down to Margaret River, north is too far. Its cheaper to go to Bali and the waves are way, way more consistent

You don't surf Rotness?

No. Its about $80 return on a ferry, about an hour to get there. Then its 5k on a bus. Then its onshore so you catch the bus back and then the ferry then drive home.

[Hatchnam]

Am I getting the hang of it..?

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

[steve shearer]

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.

[Cranked]

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.

[Cranked]

Am I getting the hang of it..?

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.

[Nick Carroll]

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?

[Beanpole]

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

[Legion]

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

[BA]

Holy shit.

[steve shearer]

that was Chris cote.