Yes, pretty ancient, and probably brittle, but I only ended up with a mild concussion, not a fractured skull.
I have no clear idea of what happened, except there was a big bang, and then I was standing in the water, wondering where I was.
There was my DIY #3 in the recess on top of this helmet, undamaged but the electronics moved sideways a few mm in the housing.
I also had 2 esp units, one on the boom and one on my arm. So I'm trying to figure out what happened by looking at all 3's tracks.
Only my right arm track went under water, port boom and head stayed above water, they just lost accuracy due to change in orientation
Here's the graphs.
The vert line is just after the beginning of the crash, I suspect the U shape in the green line there, is my head getting hit
Green is on my head,
blue is on the boom
red is on my upper arm.
The arm unit is an M10 device @5hz. when it looses all sats, it assumes it's going through a tunnel, and continues logging the speed at sat loss, so that's why there's a straight line, instantly dropping to near zero as the GPS surfaces as it discovers it's not where it thought it was.
I think this is where the harness line snaps, and arm and boom part company.
and tracks at this spot.
I was wondering if a snapped harness line caused the crash, but it appears not, if my interpretation here is correct.
I don't remember 2 bangs, the helmet splitting would have been quite loud in my ear, so this reinforces the helmet hit happening very early in the crash so what hit my helmet?????
Also looks like my head and shoulder are doing very different speeds during the crash. You'd think that would be a big neck strain, but no sign of that, in fact the only ill effect was a mild headache for a few hours, after the concussion effects cleared.
Any thoughts, anybody??
I think you must have hit something quite hard with your head, considering your broken helmet and mild concussion. The only comparable crash that led to a light concussion was a catapult Nina had, going close to 30 knots. She could not say what caused the crash, but hit both front and back of her head (probably mast and boom). Her harness line did not break, and that was the last speed session she did without a helmet. It took her maybe 10 minutes to get going again; I had almost reached her paddling out. Your crash probably was of similar or higher intensity.
Looking at the accuracy values, the boom unit goes up first, but then the head unit goes up most. Quite possible that you were upside down a bit then, with your helmet pointing to the water. The sequence would be that you hit something in the water, get launched into a catapult that tumbles you upside down, the harness line breaks perhaps when you hit the water, or more likely your gear, and it takes a couple of seconds before you're right side up again (when the helmet unit shows speed close to zero).
An alternative scenario would be that your harness line broke in the middle of a fully powered run, the sail got ripped out of your hands and hit the water, the sudden stop made you tumble / catapult, and you either hit your gear in the fall, or your gear hit you when you were down. The earlier increase of the blue line supports this scenario, but it's pretty weak evidence. I would not trust any of the speeds or waypoints after the first error estimates go above 1 - there's probably some interpolation going on after that in some or all of the GPS units.
I must admit that Albany is becoming a bit of a scary place. Glad you made it out relatively unscathed.
Select to expand quoteImax1 said..
Wow ! Proof that a helmet is a good thing. If I'm planing , I wear a helmet.
That's why I posted the helmet pic, this can be a dangerous sport.
I'm glad you're ok Mike. Didn't hit something in the water as breaking a line usually means you fall backwards.
Select to expand quotekato said..
I'm glad you're ok Mike. Didn't hit something in the water as breaking a line usually means you fall backwards.
I think the catapult was started before the line broke, but as Peter says, the error values are too high to make much of the data. Unfortunately Flex's drone was looking elsewhere at the time, video would be really helpful
Hope you are OK Mike. 
That would have been a bit of a scare. 
It does sound like a catapult type if crash after hitting something in the water, and where your head hit the mast or boom, but thats just a guess. Could have been some different variation of course. I any case, I am very glad the helmet did its job.
It always dismays me when I see sailors without helmets speed sailing, or even free sailing or wave sailing. Often, the main reason I hear is simply 'vanity', or not looking cool. Personally, I am well past caring how I look, and prefer to be as safe as possible. 
Fyi there's at least one mysterious solid underwater object east of the 'smelly mile' which unfortunately my Fangy Fin discovered in Jan 21 causing considerable impact damage to my trusty old Rocket, creased and cracked from rail to rail, so there's a possibility that it may have stopped you too Mike
Can you send me the tracks? I've got Reg's crash tracks from Anita, be interesting to see how they all line up
Select to expand quotedecrepit said..
Can you send me the tracks? I've got Reg's crash tracks from Anita, be interesting to see how they all line up
Sorry Mike, don't use GPS.
Remember it vividly, had gybed upwind of the kitesurfing launch area in fresh easterly and was heading north on a beam reach when roughly 1/3 of the way across Fangy fin impacted with a hard object judging by the sound and the lack of give. Thought a bit unusual to hit something underwater as tide was relatively high at that time. Sailed straight back to Harding Rd on an approx 20-30 deg broad reach after this. Shane Coleman (Shane121) was the only other person there at that time. Paddled out in kayak at low tide a few days later to survey the approx area but couldn't spot anything obvious.
Hope you've mended ok!
