"We have four-metre swells down the south coast and peaking at about three metres in Sydney and, while it isn't quite the 18 metres Tassie is having, it is still big and heavy," he said. "There is a southerly swell coming through and what we are expecting is a pulse coming through today and the surf to actually get bigger. "Southern Sydney is expecting six to eight foot waves while Manly is currently experiencing four to six foot waves, but that has grown just in the last hour." Mr Palmer said the good surfing conditions should remain until a slight wind change tomorrow. He also warned that surf conditions from the shore might seem deceptively calm.

"There are going to be significant lulls during sets, so beginners should be aware that it may look calm and fine but you need to be careful as you don't want to be caught in eight-foot sets," he said. Mr Palmer said Tasmania is recording eight- to 10-metre waves While he said yesterday's 18.4-metre wave in Tasmania was the highest ever recorded In Australia, he pointed out records go back only a short time. "It is the highest recorded wave and some people are calling it the biggest wave on record, and that is technically correct, but it might be a bit misleading as records only go back 10 years and I am sure there has been a bigger wave," he said. Mr Palmer said the surf will begin to drop tonight but will remain steady around Sydney until early next week.

"All this has been caused by a big, big low which is now hitting New Zealand and is moving away from us for the weekend," he said. He said the weather would remain clear over the weekend. However, one Herald reader and wave expert said that Tasmania’s huge wave yesterday was no record breaker. Tom Shand, who works at the University of NSW Water Research Laboratory, provided a CSIRO report that points out that a wave of 19.83 metres was recorded in 1985 during a storm of the west coast of Tasmania. Another wave in the same location during the same storm was recorded showing a height of 18.87 metres.

Mr Shand said the largest wave recorded on the NSW coast was 13.7 metres off Botany Bay in May 1997. "It’s worth bearing in mind also that, while a maximum wave of 18.4 metres sounds impressive, a maximum wave is a singular event and can be caused by just the superposition of two waves," he said. "The more usual height to refer to is the significant wave height, or the average of the largest 1/3 of waves. This is the height that [the Bureau of Meteorology] etc give in their forecasts. Loading "Yesterday’s peak significant wave height of about 10.2 metres is (I believe) fourth largest for that buoy."

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