No problems with the Velcro coming undone? (or do you use the lanyard as a backup safety around the arm)

Jake, never used it for catsailing, and I only look at it after each run while windsurfing, I find at over 27knots I can`t find the courage to look at instruments.. But mounted correctly on your forearm you could read it easily while catsailing.
I tie the lanyard to my wetsuit zip tether, so if it slips off the arm in a big swim I won`t lose it. (It mounts on my upper arm for windsurfing)
The Velcro strap is a stretchy material, so you get someone to put it on over your arm where you want it, and close the velcro, I then just pull it off my arm after a sail, never undo and redo the velcro, or it might wear out after a while. Just pull it onto my arm again for the next sail. It is a bit more difficult to fiddle with the buttons in the pouch, but as mentioned I only use it for speed runs, so reset max speed is the only function I use often.
The velcro strip is really wide and has a positive grip, I can`t see it ever coming undone.
PS : top speed run at our pond is now a shade over 47knots (2 sec average)by a Kitesurfer. It`s a far cry from a 500metre run, but DAMN THAT IS FAST...

Cheers
STeve