SS, please - if you spent so much time playing with antennae, you should surely know that SWR stands for "Standing Wave Ratio", not "Sine Wave Ratio". There's a lot of difference.Thanks Jack :-( I'm not the font of all knowledge.
A few observations that some above have failed to realise. Perhaps never used an AIS or even a VHF.
There are a number of reasons why a boat will not be identified on AIS much less Marine Traffic. Firstly the AIS ident is provided via VHF which is already a weak signal from a racing yacht and entirely dependant first of all on the transmission circuit. AIS was, after all, initially designed for vessels of over 300 tons which are an infinitely more stable transmission platform and being generally built in steel provide a much greater ground plane for radio transmission (read the books)
During my mi-spent youth (a long time ago) i was part of the CB Radio crazy that swept the UK. In fact i was secretary of a club of 4,800 - i was right into it.
If your 'rig' - the radio and antenna was tuned badly you would be lucky to be heard a few blocks away but get it right, particularly the SWR of the antenna and you could speak to the USA from the middle of England and I have done so.
The AIS set up on most yachts uses a splitter to enable the same antenna to be used for both AIS and VHF transmissions. That in itself reduces the effectiveness (read reliability and range) of the signal of both transmissions and i bet like most yacht installations it has never had an SWR meter within half a mile of it.
On my own boat i eschew this set up and have a dedicated antenna for each system - a bit more clutter but a lot more reliability.
One also has to realise that it is all operating in a marine environment. Were the cable junctions secure and damp and salt free, the GPS and VHF connections on the AIS, the splitter (in and out).
I cannot see the NoR or SIs so cannot comment on the exact wording but there are a number of reasons why an AIS is ACTUALLY SWITCHED ON and the information not getting out through to Marine Traffic
Regarding the case in point, the boat radioed in pre-race that they seemed to have a problem and the fact that the Race Committee statement quoted as a fact found that they appeared intermittently would perhaps point to a fault somewhere in the antenna circuit. I seem to remember a 100 footer in a much longer race last year that was reportedly not transmitting AIS details correctly due to a claimed circuit fault.
The change in the published decision with point 4 being removed as hiding something is a wonderful but (I believe) completely pointless conspiracy theory. Point 4 appeared in the "Facts Found" part of the decision and in my opinion it was correctly removed because it wasn't a fact, it was an opinion.
It was also erroneous in that is it relatively easy to discover how efficient an antenna system is using a Sine Wave Ratio (SWR) Meter. To measure the SWR using a sound system you key the mike, to measure the AIS you just switch it on to transmit. Also if on switching on the AIS the SWR meter didn't deflect you would know instantly you had a problem (no signal coming down the coax) . Whether it was transmitting the position and other information would be easy to check on another AIS receiver.
That said, these would be dockside checks and unlikely to be performed on the fly, especially when racing and a yacht is likely to be completely oblivious to the fact that they are "AIS invisible" unless specifically told so.
I use as a point of reference for this multiple conversations and advice over the years from my closest UK sailing buddy (and excellent mainsheet trimmer) who has spent his entire working career (40 years - he's an old bugger like me) with mobile communications all the way up to satellite dependant yacht telematics. (Look it up) AIS is a puppy by comparison.
My final comment i would direct to Shaggybaxter. I dare you to tell Nev Willis to his face that you have zero respect for him. I have worked with him and found him to be straight arrow. Apart from anything else he was only one of 4 Judges in this case, all of which hold various levels of Judge certification.
The actual decision? Well the RC are quoted as saying that the AIS reception from the yacht in question was intermittent. Does that not mean that they could be seen sometimes and not others? That points very strongly to a faulty system unless they were flicking it on and off which sounds pretty doubtful to me.
I may have missed something and the above is just some thoughts FROM A DISTANCE.
It's an absolute bugger being a judge or umpire. One party in the room is always going to be happy and the other party pissed off.
Come back at me if you think i am wrong - it is how we learn after all.
See ya on the water (soon i hope - bloody virus)