Analysis: New buoy records Fiji swells

Craig Brokensha
Swellnet Analysis

As groundbreaking as the 2012 Volcom Swell and the weekend's Ramon Swell at Cloudbreak have been, we've never been able to ascertain how big the open ocean swell was. That's because we've never had real time buoy observations to analyse the signature of each swell. There are no buoys in the path of Fiji swells. Nothing in the Southern Ocean, Tasman Sea, or around Fiji itself.

That all changed earlier this month when a new wave buoy was deployed off Fiji's Coral Coast, offshore from the small village of Cuvu, approximately halfway between Cloudbreak to the north-west and Frigates to the south-east.

In 1991 a buoy was deployed off Frigates, yet it only lasted a year, but this new buoy is permanent and will fill a crucial data gap in the South Pacific Ocean, while also helping calibrate global wave models.

The bonus for surfers is not only to geek out on the data from the weekend's back to back XXL swells, but also use the buoy to confirm the arrival of new swell energy across the region and plan trips out to the reefs.

Coming back to the past weekend (see images below) and we can see that the two swells weren't dissimilar in size at their peaks.

The first kicked strongly Friday afternoon and peaked overnight to a significant wave height of 4.67m before dropping steadily Saturday, while Sunday's swell pushed close to this size through the daylight hours, but then peaked at an incredible 4.91m at 11:20pm.

The main difference though were the peak swell periods, with Friday/Saturday's coming in just under 15s, while Sunday's was a stronger 17s.

Both swells, however, peaked under the cover of darkness. Considering what Ramon Navarro and Makua Rothman rode while the sun was up, it's worth thinking about what could have been. To put it bluntly: it's highly likely that even bigger waves broke at Cloudbreak during the night.

Next time, hey?

Sunday's swell which hovered above 4m at peak periods of 17s has set the new benchmark for swells in this region, and will be referenced in future years. As long as the buoy stays anchored in position!

Comments

Clam's picture
Clam's picture
Clam commented Wednesday, 30 May 2018 at 8:40am

Mark Visser, might have been out there with a headlamp and torches aka the "night rider" ?!

Lanky Dean's picture
Lanky Dean's picture
Lanky Dean commented Thursday, 31 May 2018 at 3:45pm

I must say I was really impressed when Visser rode that one jaws swell at night. No one saw that coming.

zeta's picture
zeta's picture
zeta commented Wednesday, 30 May 2018 at 8:44am

your sampling rate is 2.5 hours (assuming its some mean from a higher sampling rate or a calculation from energy) and you think that your analysis can pick up a single set?
If the buoy would have been placed at cloudbreak the graph could easily have a maximum somewhere else during the day..

thermalben's picture
thermalben's picture
thermalben commented Wednesday, 30 May 2018 at 8:50am

There's many things to infer from the data. A buoy off CB may have recorded bigger waves, smaller waves, an earlier peak, a later peak - we'll never know. But having closely observed clusters of buoy data for the last seventeen years (across the NSW/Qld coasts), my take is that nothing is guaranteed - buoys that should record stronger energy don't always do so, and trends across the buoys never always pan out as they should either.

Based on the broad data presented above, Craig is correct in theory that the biggest waves may have occured overnight. Of course, we'll never know but it's a great place to begin the discussion, eh?

Island Bay's picture
Island Bay's picture
Island Bay commented Wednesday, 30 May 2018 at 8:56am

Is the data accessible for the general public?

Craig's picture
Craig's picture
Craig commented Wednesday, 30 May 2018 at 8:59am

Here ya go Island Bay.. Fiji Wave Buoy

Change the sampling rate to 300.
Island Bay's picture
Island Bay's picture
Island Bay commented Wednesday, 30 May 2018 at 9:00am

Cheers mate!

Steev's picture
Steev's picture
Steev commented Wednesday, 30 May 2018 at 9:15am

I read the marker being on 11.20 AM not PM on Sunday. As it's all in 24 hr time. By 11 pm the swell has dropped to around 3.5m. For Friday it peaks around 10.30 AM.

thermalben's picture
thermalben's picture
thermalben commented Wednesday, 30 May 2018 at 9:20am

Time is usually displayed in UTC, which is denoted by the 'Z' at the end of the timestamp (Z stands for 'Zulu', though its actually denotes 'Zero' - as in +0 hours - but by using NATO phonetic alphabet, this was assigned to Zulu).

Fiji is UTC +12 hours.

Steev's picture
Steev's picture
Steev commented Wednesday, 30 May 2018 at 9:39am

Ah yes, does make sense having everything in UTC so swells can be tracked between buoys in different time zones without having to work out the time differences.

Craig's picture
Craig's picture
Craig commented Wednesday, 30 May 2018 at 9:21am

The timestamps are in UTC Steev.

I double checked this yesterday.

Ie 11:00 = 11pm and 23:00 = 11am.

You can compare it to this morning's data which has the latest update 2018-05-29 T22:27, which is acutally 10:27am on the 30th, not last night.

Very confusing and would be easier if set to local time.

thermalben's picture
thermalben's picture
thermalben commented Wednesday, 30 May 2018 at 9:26am

Snap!

Met/Ocean convention needs a standard though so it makes sense to display in UTC. An additional local timestamp would be handy though.

scoopmaster's picture
scoopmaster's picture
scoopmaster commented Wednesday, 30 May 2018 at 9:32am

That buoy will be a pretty handy fishing spot too, mahi mahi, yellowfin tuna and wahoo anyone??

thermalben's picture
thermalben's picture
thermalben commented Wednesday, 30 May 2018 at 9:33am

As long as no-one ties up their bloody boat to the mooring.

Distracted's picture
Distracted's picture
Distracted commented Wednesday, 30 May 2018 at 12:40pm

Fascinating how a 5m swell plus swell period in the open ocean translates to that monster that Navarro was on.

Clam's picture
Clam's picture
Clam commented Thursday, 31 May 2018 at 3:19am

More closer to 4.5 m if your rounding it off i think.
The 4.9m spike was in the night but in the daytime it was hovering between 4 - 4.5m.
I find buoys are very accurate on big clean swells and you can virtually see the spike on the buoy and you can see it when your surfing the swell on the day . Even if the buoys miles away, (hundreds of miles even) Thats just my opinion and its cool if some don't believe that no worries. Its actually not hard to notice, but you probably have to be there to feel it, and tune into the energy of the swells in some way .
A big wave break makes it hard to miss the obvious rhythm of XXL sets

WarHawk's picture
WarHawk's picture
WarHawk commented Thursday, 31 May 2018 at 10:19pm

Reasonable to assume that CB is a bit of a magnet? Or perhaps the swell just happened to hit it better than the buoy location