Cape Sorell Waverider Buoy

[Grooter]

For the weather experts

With the current Point Lonsdale buoy being out of action in the last few weeks knowing what size swell is coming through is proving rather difficult.

I know the Cape Sorell Buoy is another measure for Victoria but obviously being located about 10km West of Cape Sorell means that knowing what is happening at this point and the time and effect it would have on the Mornington Peninsula is a bit of a science.

Can anyone tell me, in simple terms, how I can use the information this generates to predict how big a swell is and long it is going to take to reach the Mornington Peninsula?

[AZ]

If you want an ultra simple formula. Try sig wave heights and max wave heights at Sorrel in metres = wave height in feet at Flinders (for anything with a peak swell period over 12-13 seconds).

Eg. 4m sig and 6m max at Sorrel equals 4-6ft at the outer reefs at Flinders.

Allow about 4 hours time lag.

That should do you. Get out there Monday. That's the day. Should be OK at Gunna tomorrow but a bit lumpy and bumpy.

[Donweather]

Nice rule of thumb Alex. Very nice. Just one question though......doesn't this depend on the swell direction at Cape Sorell? ie if the swell direction is W'ly as opposed to S'ly wont this make a difference to the swell arriving at Flinders.

BTW, How do you tell the swell direction from the Cape Sorell Wave Buoy?

[Grooter]

That was a pretty good rule of thumb AZ thanks heaps mate

Was quite accurate too, it was showing 2 - 3 metres around 0200 and 0300 this morning and sure enough Flinders was definitely around 2 - 3 foot. Nice morning session too, got some decent rides

Don in regards to direction yeah I reckon it would make a decent difference. Flinders can work on a WSW swell but it will be a lot smaller in size than the Bass Strait beaches on the Mornington Peninsula (sometimes half or less). Likewise Westernport will get practically nothing, I've seen the Point Lonsdale buoy record 2 - 3 metres WSW swell before and witnessed barely a ripple at Point Leo.

A SW swell will be a lot closer in size to the Bass Strait beaches for Flinders and you'll also get waves in Westernport Bay. Generally a 3 metre SW swell at Gunnamatta equates to a 1.5 metre swell at Point Leo and around a 2 - 2.5 metre swell at Flinders.

But then wind and tides also make a big difference too, I've been surfing these beaches for the better part of 15 years and still can end up scratching my head some days wondering why things aren't the size, direction etc.. that I thought they would have been

[Grooter]

Cheers thermalben for updating Swellnet explaining the speed of the swell periods relative to Cape Sorrell and Cape Otway

[For those interested, an 11 second swell train travels at about 30km/hr, and a 14 second swell train travels at about 40km/hr. So, allowing for approximately 120km between an equivalent point in the swell window between King Island and Cape Otway, relative to Cape Sorell, this means that the 14 second swell train took about 3 hours to reach the coast, whilst the 11 second swell train took about 4 hours. NB - these calculations wouldn't be necessary if the Pt Nepean buoy was online!]