Re: Another weather website
Posted: 04 Oct 2017, 15:46
Hi jb2020,
The devil is in the detail. Several years ago when Willyweather was set up BoM only had about 50 ports around Australia they provided tide times for. Willyweather referenced each of their locations to one of these ports and put in a time offset for that spot to specify its tide times.
Since those early days BoM has increased its tidal information service and now provides data for 708 ports around the country. The port data supplied by BoM is calculated using fourier transforms and takes into account the particulars of that location like long/lat, moon/sun position, hence it offers a very precise tide for that location. Fish Ranger uses the full 708 ports BoM supplies data for whereas Willyweather still uses a a small number of ports from their early days, they have not upgraded to use the full suite of ports. This is why you will see differences in tide times and heights.
Take for example Bouchier Channel in Western Port, that is a location where BoM started provided tide data for recently. Fish Ranger uses BoM's tide data for that reference port whereas Willyweather still references tides at Bouchier Channel back to Stony Point.
On the fish Ranger page click the little (i) next to the tide chart, it says 'Tide Times based on Bouchier Channel'
https://www.fishranger.com.au/tides/sun ... r%20Chanel
Now go to Willyweathers page for Bouchier, go to Tides, and click the little (i). It comes up and says "the tide times for Bouchier Channel have been adjusted by 40 mins for low and 40 mins for high off the official tide times for Stony Point"
https://tides.willyweather.com.au/vic/g ... annel.html
Now go to BoM's tide page and you'll see they have a reference port at Bouchier Channel:
http://www.bom.gov.au/australia/tides/#!/vic
So you can see Wilyweather are not using the Bouchier Channel port times supplied by BoM, they are using the tide times for Stony Point then saying Bouchier Channel high and low are 40 mins after Stony Point. This is a crude approximation.
This is very likely the reason you notice a disrepancy at the location you are looking at. If you tell me the location I'll check it out for you.
Joe
The devil is in the detail. Several years ago when Willyweather was set up BoM only had about 50 ports around Australia they provided tide times for. Willyweather referenced each of their locations to one of these ports and put in a time offset for that spot to specify its tide times.
Since those early days BoM has increased its tidal information service and now provides data for 708 ports around the country. The port data supplied by BoM is calculated using fourier transforms and takes into account the particulars of that location like long/lat, moon/sun position, hence it offers a very precise tide for that location. Fish Ranger uses the full 708 ports BoM supplies data for whereas Willyweather still uses a a small number of ports from their early days, they have not upgraded to use the full suite of ports. This is why you will see differences in tide times and heights.
Take for example Bouchier Channel in Western Port, that is a location where BoM started provided tide data for recently. Fish Ranger uses BoM's tide data for that reference port whereas Willyweather still references tides at Bouchier Channel back to Stony Point.
On the fish Ranger page click the little (i) next to the tide chart, it says 'Tide Times based on Bouchier Channel'
https://www.fishranger.com.au/tides/sun ... r%20Chanel
Now go to Willyweathers page for Bouchier, go to Tides, and click the little (i). It comes up and says "the tide times for Bouchier Channel have been adjusted by 40 mins for low and 40 mins for high off the official tide times for Stony Point"
https://tides.willyweather.com.au/vic/g ... annel.html
Now go to BoM's tide page and you'll see they have a reference port at Bouchier Channel:
http://www.bom.gov.au/australia/tides/#!/vic
So you can see Wilyweather are not using the Bouchier Channel port times supplied by BoM, they are using the tide times for Stony Point then saying Bouchier Channel high and low are 40 mins after Stony Point. This is a crude approximation.
This is very likely the reason you notice a disrepancy at the location you are looking at. If you tell me the location I'll check it out for you.
Joe