Tides out of Whack?

[Knackers 696]

The other tide thread got me thinking why are the tides on websites sometimes contradictory.Today for example the BOM and Willy weather give low tide at Thevenard at 2002 hrs at 0.5m. http://www.bom.gov.au/cgi-bin/oceanography/tides/tide_predications.cgi (remember to correct for DLS)http://tides.willyweather.com.au/sa/eyre-peninsula/thevenard.htmlTides for fishing gives it as 1855 hrs at 0.4m.http://www.tides4fishing.com/au/south-australia/thevenardThats a whole hour out. Also T4F is sublety different in most tides (height and time) Anybody have the tide tables to refer to? I come across this a bit and always use the BOM as my authoritive source. I think T4F is an international site and use different data which seems to be corrupted.

[urhookedfish 12]

Hey Knackers, I find the tides on Willyweather to be fairly accurate when fishing out from Osullies. Most of the time its spot on.

[Kingsley 19]

I'm not sure how the other sites do it, but I would only be trusting those from BOM.What they do is take a sample of actual tide heights and times over a period of time (at least a year) from their tide height gauges around the place, run quality control on the data, then run the resulting "tidal frequency file" for each location through their modelling software to give predictions on future tides for each location.The other sites most probably use their own data, or old data, or their modelling software is different etc. or they've hired a monkey to manually type out the tide charts and he ran out of peanuts.If you'd like a really good explanation as to the difference, you could always ask the National Tidal Centre, I think they run tide analysis courses as well :)http://www.bom.gov.au/oceanography/projects/ntc/ntc.shtmlHave a read of this gear and you will see that tide prediction in Australia is particularly difficult.ftp://ftp2.bom.gov.au/anon/home/ntc/TidesWorkshop/CourseNotes/TidesWorkshop2011_Theory.docftp://ftp2.bom.gov.au/anon/home/ntc/TidesWorkshop/CourseNotes/TidesWorkshop2011_TidalModelling.pptThen tell me if you think the 'other sites' do the same work or have access to the same data in order to do their tide predictions.Always trust the BOM

[Kingsley 19]

Anybody have the tide tables to refer to?

Enjoy THEVENARD TIDES 2012THEVENARD TIDES 2013THEVENARD TIDES 2014

[Knackers 696]

Thanks Kingsley. Interesting, the tides tables list a high at 1900.

[Kingsley 19]

Thanks Kingsley. Interesting' date=' the tides tables list a high at 1900.[/quote']What tide tables say high at 1900?From BOM:Wednesday 12 Time Height0004 2.010619 0.311121 1.031902 0.53From Tide Chart:12WED0004 2.010619 0.311121 1.031902 0.53From Willy Weather (adjusted for DST):WedDec 12High 1:04am 2mLow 7:19am 0.3mHigh 12:21pm 1mLow 8:02pm 0.5mSeems like Willy uses BOM tides and add the hour for daylight savings, then round the heights to the nearest 0.1

[Knackers 696]

My bad. Didn't add an hour to he tide tables.