thermalben, 1528495321
Behind the scenes, we've been working on some coastal analytical tools over the last few years. This morning our Greenmount surfcam randomly captured what appears to be swash-based reflection through the surf zone.
The angle of the surfcam (facing E/NE, almost perpendicular to the direction of the energy) shows that the wavelength is very short. It can't be northerly windswell, which would look much more peaky and delineated - besides, upstream winds have been out of the southern quadrant for the last few days.
Instead I suspect these are reflected waves off the beach following a spell of surf beat (i.e. a set, or several sets of waves). Interestingly, you can see small scale refraction and diffraction as this energy passes through a couple of of gutters extending north from the shoreline.
morg, 1528498022
Newy point definitely gets them at certain times. They tend to throw unsuspecting SUP riders off too.
thermalben, 1528499253
I’m not talking out wedgey rebounds though (which can be surfed.. as per Knights in SA). In the lineup you may not even notice these tiny reflective waves passing underneath.
lostdoggy, 1528503265
Could it be from a boat?
thermalben, 1528504029
That’s a possibility, but there appears to be a lot more waves than what a standard boat wake would produce.
thermalben, 1528504337
Wow. I just checked the Surfcam Replay, and there is no sign of a boat (and any subsequent wake) - but the lines seem to be coming from the north. Kinda trippy looking, actually.
https://www.swellnet.com/surfcams/greenmount/replays#/2018-06-09/139215
lostdoggy, 1528504717
Check the top left of the kirra footage from around 3.50.
lostdoggy, 1528504893
Does look more like wind swell to me though.
John Eyre, 1528508039
Mysterious......
thermalben, 1528515305
Hmmmm.. looks like couple of skis doing circle work off Kirra.. but the waves don’t look like ski wake to me - however I might be mistaken. Def not windswell I reckon.
Craig, 1528521776
Weird, looks like boat/ski wake to me.. but again too many close spaced ripples.
lostdoggy, 1528522145
3 skis going back and forth though. Sometimes against each other. could do it.
thermalben, 1528525463
But.. if the skis were going back and forth, there’s no way that the swell lines would be so perfectly spaced apart.
lostdoggy, 1528528778
They wouldn't catch up to each other and arrange themselves?
thermalben, 1528529089
No. At a bare minimum there’d be irregular spacings. Some would overlap, and depending on the driving pattern we’d see differing responses along the length of the Superbank.
lostdoggy, 1528529635
Final suggestion. haha
A humpback whale breaching.
thermalben, 1528529963
Saw four of ‘em today so I suppose that’s a possibility!
Jamyardy, 1528547312
Primary/secondary swell refracting on the sea floor ?
thermalben, 1528575060
Here's another older example from the Coal Coast, overlooking Thirroul.
The key here is that it's the sun glare that makes it visible. As soon as cloud cover eliminated the glare, you couldn't see these waves at all.
And in this case, it's interesting to note that there was little regional wind either (image taken at 7:57am, Sun 13th Nov 2016) - Bellambi and Wattamolla were under 10kts at the time the image was taken, and for the preceding 12 hours too, mainly W'ly in direction (BOM obs data via Weatherzone, below).
[img]https://imgur.com/c1IAdd1.jpg[/img]
[img]https://imgur.com/B6AjNTN.jpg[/img]
[img]https://imgur.com/8louPiz.jpg[/img]
gcuts, 1528588339
Look at the 2 min mark and the lines are out past the peak at Snapper.
It's the wake from a vessel, jetski or boat running at fair speed, for a long distance. If a couple of jetski ran behind each other, the wake would be like this.
The the image capture later, as posted above, doesn't have the lines running as far out, which would more align with a vessel turning and so the lines are more condensed.
Can you pick up any footage from the sweep past North Cooly. The surf life saving base is there and they may have been running IRB or jetski's off the stretch of beach.
thermalben, 1528589700
Bugger. You’re right. 2:05 mark here:
https://www.swellnet.com/surfcams/snapper-rocks/replays#/2018-06-09/139209
I’m amazed at just how much wake (i.e. how many lines of swell) was generated by a small boat. I suppose my preconception was shaped by my experience with wakeboard boats.
thermalben, 1528601640
By a complete stroke of luck, a boat sauntered into view at our Trigs (South Oz) surfcam just then - allowing me to take some snaps on the surfcam. This shows the boat wake from an ideal angle. Nothing like what was seen at Snapper!
[img]https://imgur.com/I7ksMlX.gif[/img]
udo, 1528602099
oily 2 stroke trail ?
thermalben, 1529011606
Random snap from our Coolum surfcam shows some interesting features - is reflected wave energy off the sandbank leading to the formation of a quasi-standing wave in its lee?
[img]https://imgur.com/TcqDA58.jpg[/img]