What's the deal with the turnagain bore?
So I went to the presentation at the bird point overlook on saturday. The lady there explained that in order for the turnagain bore to form there had to be at least a 30ft tidal interval, and at least a -1 low tide.
The tide interval on saturday was right at 30 feet, and the low tide was a -2.9
The bore that day was, in a word, boring. There was a small amount of rough water at the leading edge of the tide, but it was anything but a wave. The tide did come in very quickly, but it definitely wasn't a bore in the classic, ridable sense of the word.
I was chatting with another guy watching for the bore, and he mentioned that he had stopped to watch it on wednesday at the same location because he had seen some surfers in the water and was curious about what they were doing. The bore came in as a wave that day, right by bird point on towards girdwood, and the surfers were able to ride it. The tide interval that day was only 29 feet, and the low was -2.36
Call it coincidence, but on the day the bore actually formed a surfable wave, the surfers were there. On that sunny saturday that there was no appreciable wave, there were no surfers to be found.
Obviously there is some other factor at work here, besides the raw numbers of the tide. Is it just a matter of chance, or is there some other quantifiable value that I'm failing to factor in?
For the record, the lady giving the presentation on the bore didn't know.
Whatever the secret is, the surfers aren't advertising it. Anyone know the trick?
Not that I'm any sort of expert on it, but it does seem that wind plays a part in the formation of the wave. If the wind is blowing down the Arm at low tide it tends to pile the water up and delay the wave, making it larger. I'm just gathering this from observations and logic, but it does seem to hold true in my experience. Also, you didn't mention it but probably know it, the minus tide needs to be before the high tide an not after it.
I also notice that wind commonly blows down the Arm on sunny afternoons, making for good afternoon wind surfing conditions. Combine that with a large incoming tide and you have a good bore wave to ride. As a bonus, since the Sun is low in the West at the time, you can also get some awesome photos of the wave spray as the surfers are coming at you. A long lens helps.