
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??