Hey slyfox- sorry to hear about your misfortune today...

I comfrotably use my 10m Cab Element, and my Cab bar and lines on a 12m Naish Aero... However, with the Naish you have to relauch the traditional way... pull the bar and lines in very hard and fast towards you, and swim as fast as you can, and about 60 deg to the wind direction
(usually the way the kites tipping) This will always work, however, especially when out with a kite you haven't used before, it is vital to know how to relaunch in any depth of water... Because of the virtual size of a 16m kite, it takes a fair amount of wind, or a nice gust to relaunch it in such mere winds...
(under 15 knots) A few things to know... If you just sit there, the kite will keep on pulling you whatever the wind direction... if it does this... I have done this twice before when I have become out of my depth and the wind has dropped... You can sit on your board, or place it in front of you... start pulling yout kite in by pulling on ONE of the back lines \||
/ (ie - red one)... Pull the kite in until you can hold onto the leading edge... wrap up the lines, being very careful to not tangle or get any part of your body intertwined in the lines...securely holding onto your kite, undo the lines from the kite, wrap the bar up, and deflate the kite... fold it up as best u can, trying to avoid getting water in the bladder... place the kite on your board, with your bar and lines in the footstrap to keep it from slipping off if you like, and paddle in... It can be a harrowing experience, but it's something you will need to know...
With regards to the beacon which records 15 knots on some days and 23 knots on the other... I can just, and I mean just be powered on a 16m in 15 knots, mainly because I am not used to such a slow turning kite, even though I weigh a lot less than the guys... It takes a little while to get used to the feel, and pull of a big one... However, in 23 knots on my 10m, I am generally overepowed, so I would assume that being a guy and on a 12m in 23 knots, you'd be laughing... perfect winds! A reason why the beacon may be recording certain winds, and maybe less showing, is that the area you are kiting in, may not fully recieve say the NE winds that the beacon gets... The land might be a little protected from the NE winds, and therefore it's 15 knots out there, but only about 11 in there...

Tips for leaning to relaunch... Take the 16m out again (not any smaller- same kite) in similar wind conditions, maybe about 17 knots would be perfect.... sit the kite in the water and water relaunch it in about 1m of water... if you can do this, gradually move out into about chest deep water (wind blowing slightly onshore to be safe in case it picks up), land the kite in the water... leading edge down, and try to re-launch it.. over time you will become more confident doing this.. The larger the kite, the harder to relauch just because of it's sheer size... Don't always rely on the recon in the Cab kite also... sometimes this might fail or become blocked out there...
All the best mate... I hope your future kiting days aren't as nerve racking as this... Good Winds