Just general surfing stuff

Can't find the right forum, then post your general surf-related remarks here!

Moderators: Butts, beach_defender, Shari, collnarra, Forum Moderators

User avatar
steve shearer
Huey's Right Hand
Posts: 25877
Joined: Mon Oct 13, 2008 8:20 pm

Re: Just general surfing stuff

Post by steve shearer » Tue Aug 14, 2018 5:22 am

Did you not see any of the data I posted yesterday?

Actual real data.

Would you like me to interpret it for you? I thought you liked it raw.

Aren't you on holidays?
I want Nightclub Dwight dead in his grave I want the nice-nice up in blazes

User avatar
offshore1
Duke Status
Posts: 11229
Joined: Fri Aug 26, 2005 12:40 am

Re: Just general surfing stuff

Post by offshore1 » Tue Aug 14, 2018 5:45 am

Godsave can't relax till this is settled Steve.

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 6:50 am

BA wrote:
Mon Aug 13, 2018 4:08 pm
Image
Lets nip these stupid implied comparisons in the bud BA. Waves don't have any trans or saturated fats and are much better for you, just pure unadulterated energy.
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

Beerfan
Snowy McAllister
Posts: 9043
Joined: Mon Jan 30, 2006 3:09 pm

Re: Just general surfing stuff

Post by Beerfan » Tue Aug 14, 2018 7:49 am

Last 4 surf checks the surf forecast.com for my usual beach has been reasonably close to reality. First 3 times sub 100kj forecast and dead flat. This morning 450 forecast and probably waist to chest high close outs. Wind slightly off but fairly close. If nothing else it's getting me to the beach more so can't be a bad thing
we are the angry mob
We read the papers everyday
We like who we like, we hate who we hate
But we're also easily swayed

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 9:34 am

Here's the case for kJs in a nutshell.

There seems to be agreement that surf forecasts are not very good at forecasting the size of breaking waves at specific surf spots but are pretty good at forecasting the prevailing swell height and period for an area.

So its up to us to know what a specific swell height and period will produce at our local breaks. Once you are familiar with kJs I think its easier to do this. This is because I think a swell with say 500kJs will produce similar waves at your local irrespective of whether the swell is 6' at 9s or 2' at 15s, and etc for larger kJ swells.

Overall, all you need to know for most surfs is whether its under 500 (marginal for surfing) or 1000, 2000, 3000 or 4000kJ.
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

User avatar
steve shearer
Huey's Right Hand
Posts: 25877
Joined: Mon Oct 13, 2008 8:20 pm

Re: Just general surfing stuff

Post by steve shearer » Tue Aug 14, 2018 9:37 am

Surf forecast doubled the Kj reading for today here and the surf is half the size.

Please explain Cranked.
I want Nightclub Dwight dead in his grave I want the nice-nice up in blazes

User avatar
steve shearer
Huey's Right Hand
Posts: 25877
Joined: Mon Oct 13, 2008 8:20 pm

Re: Just general surfing stuff

Post by steve shearer » Tue Aug 14, 2018 9:38 am

Cranked wrote:
Tue Aug 14, 2018 9:34 am
This is because I think a swell with say 500kJs will produce similar waves at your local irrespective of whether the swell is 6' at 9s or 2' at 15s, and etc for larger kJ swells.

Overall, all you need to know for most surfs is whether its under 500 (marginal for surfing) or 1000, 2000, 3000 or 4000kJ.
That just about takes the cake for the wrongest thing I've ever read on the internet.

That's flat earth, Nick Carroll as a cross dressing novice jewfisherman wrong.
I want Nightclub Dwight dead in his grave I want the nice-nice up in blazes

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 9:41 am

Well you can do what I propose or you can read this:
Here's a fully calibrated forecast from the best forecaster in the world, daylight second: Pat Caldwell.

DISCUSSION: SUMMARY... Short-period N swell dropping with long-period S swell rising into the weekend.

DETAILED:. Mid Friday on northern shores has breakers above the summer average from 000-030 degrees. It should hold about the same on Saturday.

A long-lived fetch of fresh to strong breezes over a large area between 40-50N to the N to NNE of Hawaii 8/4-8 was sandwiched between broad areas of high pressure to the west and low pressure to the east. The pattern remained stationary into 8/8 then weakened and moved east 8/9. There should be one more day with small breakers centered from near 10 degrees then fading on Sunday.

The remnant of typhoon Shanshan is tracked east along 40N to the west of the Kuril Islands 8/10. It is much weaker than earlier model predication had given. The fetch area towards Hawaii remains small and weak in the model packages through the weekend. There could be a slight rise from 310 degrees late Wednesday.

Mid Friday on eastern shores has breakers for N exposures aforementioned and below average trade windswell from 60-90 degrees. Low conditions should continue on Saturday.

The 8/10 morning ASCAT pass still shows some fresh speeds near Oahu though just out 60 nm or less, a short fetch. Otherwise the upstream trade windswell source regions is dominated by mostly gentle to moderate speeds. Thus the windswell is predicted to reach a minimum on Saturday.

A increase in trades over and E to ENE of Hawaii is predicted Sunday into Monday that could increase the surf a notch from trade windswell. It should remain below average.

Low, longer-period E swell are expected this period from two tropical eastern Pacific systems.

Hurricane John tracked NW to the S to W of southern Baja 8/7-9. With the medium span of the system and long travel distance over 2500 nm, only small surf is expected locally. It should fill in Sunday and hold into early next week from 80-90 degrees at levels below the trade windswell average.

Tropical storm Kristy has moved slowly N along 130W 8/8-10. The compact system is modelled to turn NW and weaken over the weekend as it remains beyond 1200 nm from Oahu. This could add small surf Tuesday into Wednesday 8/14-15 from 80-90 degrees.

Mid Friday on southern shores has breakers near to a notch below the summer average. The Hector swell has dropped to low windswell while a new long-period S swell builds.

Hurricane Hector generated well above average surf locally on 8/9 from 150-180 degrees. It was similar to the size of surf produced by Hurricane John in 1994. The latter was a category 5 system with a similar track to Hector. There was a large downwelling oceanic eddy to the SW of the Big Island as Hector passed directly over Wednesday night into early Thursday. This eddy would have had warmer sea surface temperatures that in turn could have been one of the ingredients to spur stronger ocean surface winds and a wider fetch aimed at Oahu than previously modelled 8/8 PM into the night. NOAA buoy 51004 SE of Hilo reached a maximum of 20' 8/8 while buoy 51002 south of Oahu reached 30'. This validates the more aggressive wave growth once in the Oahu swell window.

Hector continues a westward component as it gains latitude well to the WSW of Oahu 8/10. PacIOOS/CDIP Barbers Point buoy is showing low, shorter-period swell within 8-12 seconds from 180-220 degrees 8/10. This energy is predicted to fade. No more surf locally is expected for Oahu from Hector.

In the southern hemisphere a week ago, a broad area of low pressure tracked NE south of French Polynesia while a large high pressure settled east of New Zealand 8/3-5. The wide, long fetch had direct aim at Hawaii. The limiting factor was the magnitude of the winds, which stayed gale or less.

NOAA southern buoy 51002 and the PacIOOS/CDIP buoys off Barbers Point on Oahu and Kaumalapau off Lanai all show the rise in low, long-period swell 8/10. The event should be filled in by Saturday from 170-190 degrees, peak late Saturday, then slowly drop into Monday.

Background summer conditions are expected to take over by Tuesday.

Into the long range, a compact gale near 35S, 150W 8/9-10 is modelled to weaken as it moves east 8/11. It could bring surf above background levels though below the summer average within 8/17-19 from 170-185 degrees.

The tiny to small WNW event from the remnant of Shanshan is expected to linger 8/16.

Surf from 50-90 degrees is expected to remain below average 8/16-17 as the low surf from Kristy drops.

Long range forecasts are subject to major revisions.

This collaborative forecast will resume on Monday, August 13.

This forecast was produced through the collaborative efforts of NWS and NCEI. Please send suggestions to [email protected] or call the Warning Coordination Meteorologist at 808-973-5275.

ADDITIONAL RESOURCES: See http://www.prh.noaa.gov/hnl/pages/marine.php

NWS Forecaster and NCEI Pat Caldwell
and unless you are Steve or Nick still be none the wiser
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 9:56 am

steve shearer wrote:
Tue Aug 14, 2018 9:38 am
Cranked wrote:
Tue Aug 14, 2018 9:34 am
This is because I think a swell with say 500kJs will produce similar waves at your local irrespective of whether the swell is 6' at 9s or 2' at 15s, and etc for larger kJ swells.

Overall, all you need to know for most surfs is whether its under 500 (marginal for surfing) or 1000, 2000, 3000 or 4000kJ.
That just about takes the cake for the wrongest thing I've ever read on the internet.

That's flat earth, Nick Carroll as a cross dressing novice jewfisherman wrong.
Here' some support for what I said from the surf forecast FAQ for kJs
Wave energy (in kilo Joules, kJ) on the swell forecast tables and maps indicates the power of the predicted waves and can be the most useful guide to how powerful the surf is likely to be at your local beach / reef. It is a function of both wave size and period (the larger the waves and longer the period the greater the power). Small ocean waves with a long period can create the same size surf as larger waves with a short period but they can have the same wave energy, making it a potentially better guide to likely surf size. We would suggest making a note of the forecast wave energy on a small but surfable day and on a day that is the biggest you are happy to surf. This should give you the energy range that is in your comfort zone. As a rough guide, wave energy of 100kJ can be just about surfable at many breaks, 200-1000kJ should produce increasingly punchy waves while 1000-5,000+ can start to get really heavy and even dangerous at some breaks
Also, where I surf the swell is from the SW or SSW about 90% of the time. Sometimes it gets really radical though and comes from the S or WSW. There's often a SE windswell but its not to bad as it has to refract so much to hit the places I surf.
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

User avatar
steve shearer
Huey's Right Hand
Posts: 25877
Joined: Mon Oct 13, 2008 8:20 pm

Re: Just general surfing stuff

Post by steve shearer » Tue Aug 14, 2018 10:09 am

Cranked wrote:
Tue Aug 14, 2018 9:41 am
Well you can do what I propose or you can read this:
Here's a fully calibrated forecast from the best forecaster in the world, daylight second: Pat Caldwell.

DISCUSSION: SUMMARY... Short-period N swell dropping with long-period S swell rising into the weekend.

DETAILED:. Mid Friday on northern shores has breakers above the summer average from 000-030 degrees. It should hold about the same on Saturday.

A long-lived fetch of fresh to strong breezes over a large area between 40-50N to the N to NNE of Hawaii 8/4-8 was sandwiched between broad areas of high pressure to the west and low pressure to the east. The pattern remained stationary into 8/8 then weakened and moved east 8/9. There should be one more day with small breakers centered from near 10 degrees then fading on Sunday.

The remnant of typhoon Shanshan is tracked east along 40N to the west of the Kuril Islands 8/10. It is much weaker than earlier model predication had given. The fetch area towards Hawaii remains small and weak in the model packages through the weekend. There could be a slight rise from 310 degrees late Wednesday.

Mid Friday on eastern shores has breakers for N exposures aforementioned and below average trade windswell from 60-90 degrees. Low conditions should continue on Saturday.

The 8/10 morning ASCAT pass still shows some fresh speeds near Oahu though just out 60 nm or less, a short fetch. Otherwise the upstream trade windswell source regions is dominated by mostly gentle to moderate speeds. Thus the windswell is predicted to reach a minimum on Saturday.

A increase in trades over and E to ENE of Hawaii is predicted Sunday into Monday that could increase the surf a notch from trade windswell. It should remain below average.

Low, longer-period E swell are expected this period from two tropical eastern Pacific systems.

Hurricane John tracked NW to the S to W of southern Baja 8/7-9. With the medium span of the system and long travel distance over 2500 nm, only small surf is expected locally. It should fill in Sunday and hold into early next week from 80-90 degrees at levels below the trade windswell average.

Tropical storm Kristy has moved slowly N along 130W 8/8-10. The compact system is modelled to turn NW and weaken over the weekend as it remains beyond 1200 nm from Oahu. This could add small surf Tuesday into Wednesday 8/14-15 from 80-90 degrees.

Mid Friday on southern shores has breakers near to a notch below the summer average. The Hector swell has dropped to low windswell while a new long-period S swell builds.

Hurricane Hector generated well above average surf locally on 8/9 from 150-180 degrees. It was similar to the size of surf produced by Hurricane John in 1994. The latter was a category 5 system with a similar track to Hector. There was a large downwelling oceanic eddy to the SW of the Big Island as Hector passed directly over Wednesday night into early Thursday. This eddy would have had warmer sea surface temperatures that in turn could have been one of the ingredients to spur stronger ocean surface winds and a wider fetch aimed at Oahu than previously modelled 8/8 PM into the night. NOAA buoy 51004 SE of Hilo reached a maximum of 20' 8/8 while buoy 51002 south of Oahu reached 30'. This validates the more aggressive wave growth once in the Oahu swell window.

Hector continues a westward component as it gains latitude well to the WSW of Oahu 8/10. PacIOOS/CDIP Barbers Point buoy is showing low, shorter-period swell within 8-12 seconds from 180-220 degrees 8/10. This energy is predicted to fade. No more surf locally is expected for Oahu from Hector.

In the southern hemisphere a week ago, a broad area of low pressure tracked NE south of French Polynesia while a large high pressure settled east of New Zealand 8/3-5. The wide, long fetch had direct aim at Hawaii. The limiting factor was the magnitude of the winds, which stayed gale or less.

NOAA southern buoy 51002 and the PacIOOS/CDIP buoys off Barbers Point on Oahu and Kaumalapau off Lanai all show the rise in low, long-period swell 8/10. The event should be filled in by Saturday from 170-190 degrees, peak late Saturday, then slowly drop into Monday.

Background summer conditions are expected to take over by Tuesday.

Into the long range, a compact gale near 35S, 150W 8/9-10 is modelled to weaken as it moves east 8/11. It could bring surf above background levels though below the summer average within 8/17-19 from 170-185 degrees.

The tiny to small WNW event from the remnant of Shanshan is expected to linger 8/16.

Surf from 50-90 degrees is expected to remain below average 8/16-17 as the low surf from Kristy drops.

Long range forecasts are subject to major revisions.

This collaborative forecast will resume on Monday, August 13.

This forecast was produced through the collaborative efforts of NWS and NCEI. Please send suggestions to [email protected] or call the Warning Coordination Meteorologist at 808-973-5275.

ADDITIONAL RESOURCES: See http://www.prh.noaa.gov/hnl/pages/marine.php

NWS Forecaster and NCEI Pat Caldwell
and unless you are Steve or Nick still be none the wiser
Really Cranked?

That makes no sense to you?

Aren't you a computer programmer and lifetime surfer?

Can you not see that trying to condense all that relevant information into one Kj reading is going to be massively misleading ?
I want Nightclub Dwight dead in his grave I want the nice-nice up in blazes

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 10:24 am

I think its a bit alienating for me because its for an area that I don't surf or think about. If it was for the Indian/southern oceans I would probably sit up and pay attention and absorb it all pretty quickly, and remember it.

I assume you have to pay to get that sort of thing though?
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

Nick Carroll
Huey's Right Hand
Posts: 21962
Joined: Tue Apr 05, 2005 9:29 am
Location: Newport Beach

Re: Just general surfing stuff

Post by Nick Carroll » Tue Aug 14, 2018 11:05 am

Nup it's UH backed.

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 11:20 am

Lucky bastards! So I should check with UWA and Udayana University on the bukit to see if they've got something similar for the Indian Ocean?
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

alakaboo
Duke Status
Posts: 18096
Joined: Mon Nov 09, 2009 3:33 pm

Re: Just general surfing stuff

Post by alakaboo » Tue Aug 14, 2018 2:07 pm

Cranked I think you need to read a bit more about waves in general.
You are mixing up ocean waves and breaking waves, and your description of what you think happens when waves break is a bit loony.
If 100 cubic metres of water, per metre of shoreline length, was deposited by each 1m high 12s period wave, Uluwatu would be hundreds of kilometres under the sea by now.

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 2:32 pm

alakaboo wrote:
Tue Aug 14, 2018 2:07 pm
Cranked I think you need to read a bit more about waves in general.
You are mixing up ocean waves and breaking waves, and your description of what you think happens when waves break is a bit loony.
If 100 cubic metres of water, per metre of shoreline length, was deposited by each 1m high 12s period wave, Uluwatu would be hundreds of kilometres under the sea by now.
I know I made gross simplifications just to get some results quickly. Instead of a box 100m x 1m x 1m think of it as a triangular shape with a base of 20m, a height of 5m and a width of 1m. This gives the same volume of 100 cubic m.

And I know applying the kinetic energy formula to an ocean wave is incorrect as the water movement is circular and does not move very far as the wave propagates. The breaking wave is going to have kinetic energy though.

I was unable to find any formula to actually calculate the energy of an ocean swell or breaking wave. I have no idea what surf forecast use to arrive at their kJs or what it represents, so essentially I'm with Nick atm. But I'm equally sure that the breaking wave has a shitload of kinetic energy.

I think I still may have come up with a ballpark estimate for very little effort though.

Have you got any method for calculating the energy of a swell or breaking wave?
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

User avatar
steve shearer
Huey's Right Hand
Posts: 25877
Joined: Mon Oct 13, 2008 8:20 pm

Re: Just general surfing stuff

Post by steve shearer » Tue Aug 14, 2018 2:43 pm

This is a pretty good entry level Cranked.

\https://www.amazon.com/Surf-Science-Int ... 0824828917
I want Nightclub Dwight dead in his grave I want the nice-nice up in blazes

User avatar
Cranked
Snowy McAllister
Posts: 7884
Joined: Mon Jun 16, 2014 7:52 am
Location: Willetton

Re: Just general surfing stuff

Post by Cranked » Tue Aug 14, 2018 3:29 pm

So you don't know how to calculate the energy of a swell or a breaking wave in joules?

I'm giving up. I'll just accept what Surf Forecast says it is.
“I don’t necessarily agree with everything I say ”— Marshall McLuhan

alakaboo
Duke Status
Posts: 18096
Joined: Mon Nov 09, 2009 3:33 pm

Re: Just general surfing stuff

Post by alakaboo » Tue Aug 14, 2018 4:32 pm

Image

Post Reply

Who is online

Users browsing this forum: No registered users and 17 guests