Time held underwater
Best way to estimate would be a 'per wave' hold down. Most 4-6ft swells would have a solid swell period (say, 12-15 seconds), so it'd be fair to assume this length of time per single wave hold down. So, if you come up for air just before the next wave smashes you, that's somewhere between 12-15 seconds (or whatever the swell period is).
I did some simulations for this at the University of Otago (NZ), when we were shooting the latest docco for Storm Surfers. Ross, Tom and I did some tests holding our breath underwater in their 'swimming flume', to see how long we'd last. The flume is essentially an oversized lap-pool that creates a fast flowing current which is used to research various parameters for their health science program.
The first couple of tests we did were within a still environment (flume turned off). The next couple of tests we did were hanging on to a tow rope (underwater!) as they cranked up the flume to simulate a turbulent current - I can't remember the speeds but it was way faster than you could have swum against. It wasn't quite like a wipeout but it still changed the underwater dynamics in a radical way.
The difference was quite impressive - for Ross and Tom, they could hold their breath for a minute and a half in still water, but only thirty-odd seconds in turbulent water. I could only manage about 70% of their times. We filmed the whole day but it didn't make it to the docco, however I reckon there's a micro-doc of it somewhere that will probably be released to the Storm Surfers website in the next couple of weeks. Was pretty interesting stuff nonetheless (apart from my pathetic performance!).
I use the 1 second per 1 foot of wave. So it works out that you will need to hold your breath for about 4 - 6 seconds. If you can hold your breath for 20 seconds while being pummeled by the front row of a first grade rugby team then you are ready for 20 foot waves.
I'll have to check out this storm surfers doco. Sounds interesting :)
Have you guys got a distributor?
It's being launched on July 15th on Discovery Channel Australia. Check out our Facebook page for more info.
Hi guys just wondering if anyone can guesttimate how long on average you get held underwater when wiping out on 4-6 foot surf. I'm talking about a one wave hold down. I wanna start training to increase lung capacity and breath holding so i dont panic when held under.