Got myself a new toy recently (waterproof digital camera).
Would be interested to take some underwater footage of people's fins going past at speed to see what's actually going on down there.
I'm guessing the finmakers out there (e.g. Mal, Tom C., Andrew McDougall, etc) might be pretty interested to see the results, as while the predictions made by the fin-designing software are likely pretty good, it's still not the real thing.
When I mentioned the idea to a few people at Speedweek, some reckoned the frame-rate wouldn't be high enough, but hey, you never know 'till you give it a go, and I'd like to give it a shot.
Who's interested?
I imagine you're trying to get a video like this one?
Hell mate. I'm up for it if you are!
Let me see...how does it go. You lay down in the shallows while I blast past cm away on the edge at 40+ knots. Yea sure. I think I can handle that!
Hey Mr T have you had a chance to try that new fin you won at GPSTC ?
If you don't want/need it i'm willing to relieve you of it.
thanks for that.
Crickey!
My own team mate and a typical Pinna boy having a crack at a cripple
Yes Baldy, only once and it seemed good but to be honest I dont have the feel yet for these things, it could be a windier day or less choppy and as I have not sailed much this season I have no idea..... I need to learn more about "How to trim the rig" and understand the changes that will happen to the kit.
Cheers GT
better check with Steve tomorrow.
nice vid!
So i may be a bit ignorant, but is that fin really bending over 20 degrees?
it seems to not be bending in a distributed fashion (ie, in a curve along it's entire length), but bending almost right at the fin box itself.
I must admit, i always assumed fins were stiff enough to remain mostly perpendicular to the board, and if it did flex, would do so almost imperceptibly. by that video, survey says no...
looking at a formula fin things can be a little out of context compared to small fins.
for starters they are 70cm long.
they are also designed to bend which increases the lift. more recent times have seen the fins get softer and the tails of the boards get wider.
modern formula boards are 80cm+ wide at the tail.http://www.gaastra.com/vapor-formula-board
the reason for the extreme lift is to help upwind performance. to get back downwind again you need the extra tail width to keep the board under control.
speed and slalom fins aren't designed to go upwind at the same speed or angle.
slalom work best across the wind
speed work best downwind.
it's interesting that the fin in the vapor board linked above looks like my 66cm C3 fin that on my old formula board with a 60cm+ tail had so much lift that over 15 knots and my knees would ache. it was a very soft fin. great upwind but difficult downwind. when i changed to the 70cm deboichet custom, a much stiffer fin, i had a lot more control. these days on modern boards my deb would be to stiff.
well that's a laymans explanation.
Waterboy, how about getting a scuba tank and a weight belt and sitting on the bottom in 1-1/2 to 2m of water while we sail over the top. Fins only draw 25-28 cm max so you can work out your own safety margin.
But I recon' you would need a flag to raise before you pop your head up. :)
Seriously, I wonder if the fin would be close enough for long enough to get anything of value?
Hey waterboy,
Being a formula fin I think the guy would be doing 30 knots max so no chance of cavitation.
I hope your frame rate is high enough to catch a fin whizzing by, although I have seen some wicked tip vortices coming off some people's fins before. They look like a trail of light brown rope. These may well stay around long enough to see what's going on.
Hey Waterboy,you had a go at my crazy idea so i guess I,ll have to give your one a go but i think the other problem will be the auto focus,it just won,t be fast enough. Can you lock it?? I have some small buoys that we could use as a marker to aim at. As to sitting on the bottom,use a snorkel, works as aim point too .Matt still got that "Darwin "weight jacket webbing to keep you firmly on the bottom[}:)] Kitters really are crazy
Howdy all!,
Sailquik - I agree, sitting on the bottom and filming from there would get some great footage and it was also something I was thinking about, but I relegated that one to second place -> if I can get the required footage from upwind, in plain view of everyone, and in water too shallow for a sailor to get to me without crashing beforehand, why take an unnecessary risk?
However if I can't get the footage by filming from the bank, I just may have to film from downwind and well out in the water.
I must admit, I'm not real keen on using a weight-belt as if (heaven forbid), I get clocked by a passing fin while filming, or while coming to the surface, I want to float to the surface where people can see I'm in trouble, not be dragged back down to the bottom by the weight-belt.
Plus I don't have scuba-gear.
What I was thinking of doing was using a pole (say 2m long?) with a flag and/or float attached to the top of it, and a large bag of sand strapped to the bottom of it.
I'm guessing I'd also need a length of rope to hang onto that's attached to the sandbag/pole junction.
I can carry this out into neck high water and this can mark my position to the speed-sailors.
In the neck-deep water I'll be able to stand upright to see what's coming from a distance, but if anyone messes up and passes too close I'll be able to duck down below the depth of their fin.
In neck-deep water I'm thinking I should be a fair distance away from where the boards are passing as most speed-runs occur in ~50cm-deep water; this extra distance should also help give the camera auto-focus mechanism a bit of extra time to keep the passing fins properly in focus.
I'm guessing there may well be a bit of current in water of that depth, but as long as the sandbag is heavy enough, holding onto the rope attached to it should keep me in place.
That way I can hold onto the rope with one hand, and as someone passes, I can sink underwater and film with the other hand.
As for breathing, if I need to stay underwater for extended periods I was thinking of using my snorkelling gear, and attaching a length of hose with a float on the end of it to my snorkel so I can get down at least a metre underwater and still keep breathing.
Craig - you may well be right about the auto-focus; not sure if I can lock it (haven't had time to read through the manual yet).
To test it though, what I'm planning to do is stand behind a barrier next to the highway (should be able to do this tomorrow on my way for a sail tomorrow) and try to film the side-mirrors of passing cars (as these are probably a little smaller (height-wise) than a speed-fin)).
As the cars would be doing 100km/h, if I can film a side-mirror at this speed I'm guessing a speed-fin passing at anything up to 50 knots from the same distance should be fine.
So even if the wind decides not to play ball tomorrow, it's still gonna be playtime for me!
Sure, my idea may sound a little crazy perhaps, but why would you want to be sane? -> the 'nutters' have way more fun than the 'sane' people!!
Besides, I reckon anyone who's into speed-sailing has got to be a little nuts -> so ya wanna help me film?
Quote waterboy:
""As for breathing, if I need to stay underwater for extended periods I was thinking of using my snorkelling gear, and attaching a length of hose with a float on the end of it to my snorkel so I can get down at least a metre underwater and still keep breathing.""""
I am not sure that this will work. There is a limit as to how long the snorkel can be before it just becomes a re-breather (and you suffocate) :(
