This morning ( 22nd November ) I visited one of my sites and noticed a series of Warning messages emanating from the [bw_tides] shortcode. There appeared to be something wrong with the tidetimes.org server. I spent a short while improving the code to better cater for errors. As I was doing it so the server appeared to recover.
It then reached a stage where there were no Warnings being shown NOR any tidal information.
This is due to the cacheing.
To recover from this change the shortcode to use a different value of store for the cached information.