Monday, 6 July 2020

Vancouver BC tide update



When I was a very young child, I almost drowned while playing a when the tide came in unexpectedly on a long shallow sandy beach. As a kayaker, I have muscle memory of the difference between paddling in the same direction as a tidal current and paddling against it. Tides are important.
Vancouver is a busy harbour. It is, in fact, the third busiest harbour in North America, behind Los Angeles and New York. The ships can be so large that they need to wait for low low tide to make their way under the first narrows of Burrard Inlet at Lion’s Gate Bridge. As well, Vancouver has several outcroppings that change between being a peninsula and an island depending on the tide, as well as sections of beach that completely disappear at high tide. A few times a year, people get stranded. Some people use their cell phone to call 911 for help, while others have tried to swim out and have died as a consequence.
The author of the Dairiki.org website advises you to not rely on the website for tidal information when you are in life and death situations.
David Flater (who is author of xtide, the program I use to produce this data) provides the following disclaimer, behind which I firmly stand:
DO NOT RELY ON THE OUTPUT OF THIS PROGRAM FOR DECISIONS THAT CAN RESULT IN HARM TO ANYONE OR ANYTHING. REALLY. I MEAN IT.
Agencies like NOAA exist because there is a need for certifiably correct tide predictions. Please do not rely on XTide if you need guaranteed results. There is no way I can get certified data on a zero budget. I rely on users like you to tell me when something is wrong. Please continue to do so.
In Canada, the equivalent of the US National Oceanic and Atmospheric Administration (NOAA) is Fisheries and Oceans Canada, operated by the federal government of Canada.
At the time of writing a blog post in September of 2013 entitled “Tides” at abilitytools.ca, the difference on the charts between high tide on the official Canadian Government tables and the XTide high tide data was about two minutes give or take. If you compare the data between official and unofficial sources in July, 2020, the difference can be as large as twenty minutes. Your results may vary depending on the station. Some unofficial tide web sites and on-line applications could have further issues for British Columbia, Canada in the future. BC plans to stop changing the clock between Pacific Daylight Savings Time and Pacific Standard Time in the fall, so tide charts will need to show Pacific Daylight Savings time throughout the whole year.
Tides can vary depending on wind, precipitation, river outflow volume and how they interact with the shape of the body of water and the topology of the terrain beneath the sea. Even with the best of data, it is prudent to prepare for the unexpected when sailing in Northern Pacific waters.

Tide sites

Official

Unofficial