Many thanks.
Paul-I believe that Chinese Bore is the largest in the world,I think it's due to it having the world's greatest difference between low and high tide too.
Mark- It will be next year before there's another 4-star in daylight. (see chart link below).I can give you directions on where to go or let me know when you want to see it, come here to my home and leave your car and I'll take you and whoever if you come with a brother or two or friend, to the two locations. I leave one as it passes and drive 3 miles to the next one and wait.It ravels at 8-10mph. I travel at 40-50..There's a location inbetween The pub and Over Bridge (Minsterworth church) but the last 3 times I've been there (and yesterday and today) the wave has broken down and I'm wondering if it's due to a shifting silt issue. I went again this morning and although the surfers on the wave got off it just before my location at Over bridge but I go down alongside the river (the bridge is heaving with spectators) the boats are worth looking at and 3 surfers got out right by me. (another lovely lass too.lol) I also had a lot more light and the 100-400 lens. Even the 70-200 wasn't really giving me the reach I needed, I had it with me and tried it.This was a 4-Star,today's was a 3-star but as good as yesterday's. I'll post them shortly.
Conor-Just to add to Paul's explanation, what assists it to becoming a good Bore- a good wave- is a South westerly coming up the river and also low pressure-high pressure sits on it ,so to speak. Then there's the Spring tides but the cause is what Paul has stated.They're quite regular and they're graded 1-5 star. Sometimes though, according to conditions, a 4 might be better than a 3 and a 3 better than a 4,so you go and take your chance.
Here's the timetable. I go to the Severn Bore Inn >Minsterworth> Maisemore (Over Bridge,Gloucester)and you can see by the timings that it's easy to go from one to another and catch it each time. From the Severn Bore pub to Over Bridge,Gloucester it's about 6 miles with Minsterworth Church inbetween.
The 5 star Bores are in red and as you see there's another at the same location 12 hours later.
http://www.severn-bore.co.uk/2010.htmI see that's pretty well it for this year.There 's a couple of 3 stars ,the 4's though are in the dark,late evening.