2ft @ 10 secs, 3ft @ 8 secs or 4ft @ 6 secs

[S4MS]

Which is best?

As a newbie I understand that in general, you'd want a solid wave height as well as period but I'm not 100% clear on which is more 'important'

Does, period correlate with 'power' whereas swell with size? Isn't a bigger wave automatically more powerful? What about speed of the wave - do either of these measures influence that?

Thanks guys

[Merry Prankster]

yes

thats a lot of questions all in there..

Here are some general rules of thumb for ya.

If a swell is one meter and the period is about 10sec then the wave will generally hit the beach at about a meter. A 15sec swell at one meter will be well overhead and have a lot more power. A lesser period will tend to be a meter or less and be rather gutless. Obviously if offshore reefs magnify or refract longer period swell this rule doesn't really hold.

From memory a 16sec swell starts to feel the ocean floor (and refract) at around 800ft and a 12sec at around 400ft - anyone care to shed some light on this or correct me..

As the size of the swell increases you generally need a bigger period for it to seem as clean.

Swell travels at around 1.5 * the period in knots out in the open ocean. Thus 10sec travels at around 15knots etc. The speed (and thus power) at which it hits the beach will depend on how quickly the continential shelf drops off etc. The quicker it drops off the lesser time the swell will have to feel the bottom and thus slow down.

Depending on where you are and the quality of beachies you surf more than about 12sec or so seems to make a lot of beachies close out. So generally I try to head for reefs, points or river bars if the period goes above that.

Other than the above you just have to watch and it may take years of observations to really understand how it all works.

[Jimi]

id prefer either the 2ft at 10 sec or 3 ft at 8 seconds.
Generally id say that all 3 of your options given there would result in approx the same wave heights at the beach, but the 10 sec swells will be travelling faster, thus with more power. When a longer period swell 'feels bottom' the wave slows, and the energy will cause it to peak up a bit higher.

One of the best surfs ive ever had was one that was reading 2 foot at 14 seconds, which resulted in wave face heights of head high to half overhead

[S4MS]

Thanks guys - that all makes sense, though it's pretty complicated eh?

I guess that's one of the best things about surfing - all these variables mean that no 2 waves or sessions are every exactly the same.

Another question for you. If you could make a wish and every hour of every day delivered perfect shaped 4ft at 10 secs E swell with light constant offshore winds, permanent mid-tide & banks that never shift would you do it?

[Jimi]

Sh!t yeah id do it. Though I might add a few more variables, like have the swell swinging back and forth from NNE to SSE, say in a week long arc, just to make sure everywhere has its day every few weeks.........


........and a never-ending pack of Timtams

[thermalben]

Anything under 8 seconds is shitful no matter what size it is.

I gotta disagree with that - I've had great waves on the Goldy during a peaky windswell in the 5-6 second range.

Different parts of the country prefer different swell periods. The Victorian reefs and beaches are primed for long period SW groundswells (nothing under 12 seconds, thanks for coming), but short period swells - even on the beaches - rarely produce anything worthwhile. The Goldy's a completely different kettle of fish - sure, the points enjoy (rare) long period swells, but they cope quite well during low period events too, and the beachbreaks are tailored for peaky windswells. Sydney offers a mix of options, depending on the swell direction and the swell period.

But on top of this, you have to check your source of buoy data. Are they all the same? No, they're not.. 8 seconds ain't always 8 seconds. This makes it even trickier to define broad statements such as "swells less than x seconds are poor" or "swells greater than x seconds are unreal".

[AlbyAl]

Anything under 8 seconds is shitful no matter what size it is.

I gotta disagree with that - I've had great waves on the Goldy during a peaky windswell in the 5-6 second range.

quote]

Whaaaat!!?? I'm gobsmacked - 5-6 seconds of windswell and it breaks OK at a beachie?? Really? Got any idea why? Because Seedknee is pure unadalterated poop at 5-6, even 7-8 is marginal and weak. Slooow lumps of water below 8 methinks.

[thermalben]

Depends on the source, and the direction. Peaky localised NE windswells on the Goldy are unreal; we get similar NE windswells down here in the summer months, usually at exposed NE facing beaches south of Sydney though. Short period S'ly swells don't seem to have the same effect along both coasts.

If the swell source is very close to the mainland, there may not be enough time for the wavelength to draw out before the energy reaches the coast. So, the resulting swell periods at the buoy are low (for the corresponding source wind speed), but you still get plenty of punch in the surf.

A good example of this was during a recent south swell, generated by a deep Southern Ocean low south of Tasmania. The Sydney buoy picked up 19 second peak swell periods from this event, however the Cape Sorell buoy (west coast Tasmania) picked up peak swell periods of only 15 seconds, as it was "too close" to the swell source. This swell generated 3-4ft waves at south facing beaches in Sydney, but the much smaller swell periods in Tasmania didn't affect wave heights at Shipsterns to any great degree (10-12ft bombs.. photos here).

[bonka]

Beaches in Qld have gentle low angle approach slopes for the waves to come in from the ocean - waves move slower over shallower water. Thats my theory on qld working better in shorter period swells (also the reason why whales beach emselves up there!) hope that made sense got to run to the bottle before underbelly starts!

[bonka]

Yeah interesting to think about bouy locations - are they all situated above the same depth of water? sand moves like crazy farkin in Qld. As for the original post - I'd take the longer period in a flash... Aimly cause it is "always" easier to paddle out - dang, then you need to take into consideration the altered "potential" crowd to wave ratio [just "minding" my broad sweeping statements that I was so warned about in geography class]

OT: Yeah funny, if you looked at the plot of the underbelly it couldn't be more plain: bang = bang = bang = bang - Well "shot" I say

[SAsurfa]

Would go the longer period swell for sure.

More power even at 2' and therefore, on a good bank, which it should feel pretty nicely it can become alot of fun

[grazza]

Short period swells are fun. Short period =:

• - More consistent sets
  - More waves per minute
  - Peakiness giving a diversity of takeoff spots
  - Interesting pockets and hollows and (for the younger ones) ramps

Sure long period offshore looks good, but the best fun surf are often on the windswells, IMHO

[mr vic]

Short period swells are fun. Short period =:

• - More consistent sets
  - More waves per minute
  - Peakiness giving a diversity of takeoff spots
  - Interesting pockets and hollows and (for the younger ones) ramps

Sure long period offshore looks good, but the best fun surf are often on the windswells, IMHO

that is true. like the guy above said, the vicco reefs and beaches love the long period swells. this is what it is most of the time as well, hardly ever below 10 and usually between 12-14 seconds.

However this does lead to less waves per minute and less spots to take off spots. can be frustrating down here when there is only a couple of take off spots on the beach, less frequent sets and 25 crew all trying to get a piece of the action.

so can be nice sometimes with a little 8-10 second period swell on the east coast, as it gives more variety and relieves the crowd pressure a little