I was searching for the very long post I did on the starboard forum many years ago, on the history of the timing gear we used at Sandy Point from 1988 onwards, but I can't find it. (Hoped it would save me a lot of typing.

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The first speed trials were held in 1988 and were organised by Mark Hardy and a group of mainly NSW sailors. It ran for a week and they used a timing gate setup that used break beam lasers to trigger the timing. (probably, an evolution of the timing systems first used on Botany Bay that have already been mentioned elsewhere in this thread). It all worked in theory, and when tested in controlled conditions, but in strong winds on the speed course it was extremely hard to keep the gates aligned and the electronics working. We managed to get through the week with a couple of days competition, but my memory of it is a bit vague so it could have been more.
After that event, a group of Sandy Point sailors got together and decided to form a sailboard club: The Sandy Point Sailboard Club. We hoped we could run a more comprehensive event the week after the 'Speed Trials' which would include more events to keep entrants entertained on the water and on the beach while waiting for serious speed sailing wind. We called it the 'Sandy Point High Wind Carnival' (1989). One of our members, Dave, said he could construct a set of timing gates using the same principle (break beam) so we went ahead with it. The HWC was to include 100m or 250m speed trials, slalom/marathon/course racing and man on man drags. We had plans for fun beach activities and evening activities at the Boardriders Bistro. There were individual event trophies and an overall (all sailing events) trophy. It first ran ran after the 1989 'Speed Classic' event and the majority of the entrants stayed for both weeks. It was a roaring success and so became an annual event up until about 1995 when we just ran of of organiser steam.
The timing gates system was a bit of a saga though, as the break beam gates were extremely hard to keep working reliably. The two big issues were the tidal current/fixing gates and the electronics/cableing. The tide and depth of the water (2m+ just 5m from the bank) made it very hard to fix the water side of the gate. We tried poles driven into the sand the first year. That was extremely hard to accomplish but we eventually got them in. Then the tide leaned them over so we had to keep adjusting the aiming beam. Then, when it got strong winds, the wind vibrated the pole and made the reflector move so much that it kept getting false readings. We missed a lot of runs which did not go down well. We also had 300-400m of cables to run out in the sand to get the signal back to the timing gear. This proved to be a massive job, trudging through the ankle to knee deep soft sand trying to unroll and roll up wet, sandy cable! It kinda worked, but there were a lot of errors and frustration. On top of that, as the wind shifted direction we could not respond to move the course. This meant the course ended up far too square most of the time.
The second year we ran, Dave made up radio links to eliminate the cables (a godsend to the workers!) and made floating buoys for the reflector gates to try and make it easier to cope with tide and setup. They were very difficult to anchor accurately, and I think we ended up driving poles in to hold them still anyhow. We were still having far too many issues with keeping the gates operating, but the wireless link worked well and the timing gear could be set up behind the dunes in an old caravan.
After that we had had enough of the infra red gates and came up with another concept which looked excellent in theory. Mick Chomley got some security cameras and set one up at each end of the course on the bank. He connected them to a couple of monitors with movement sensors in the screen. All fairly standard security camera stuff in those days. The sensors were connected to an electronic timer. In theory, the sensors started and stopped the timer and the sailors went through the course - strictly one at a time. Again, it all worked well in controlled conditions, but in strong winds with fast moving clouds or waves and foam moving on the water, there were too many things triggering the timer at the wrong time. We tried pointing the cameras at the water, but the waves and foam wakes would set them off. We tried pointing them at the sky (to get the sail to trigger them) but clouds and birds moving in the background triggered them. In the end, Mick sat in the boat with the timing gear and had to manually disable the sensors by holding a button, and only release it in the second or so that the sailor went trough the gate. I think we managed to get more than half the runs this way, but it was still quite unsatisfactory. At least, I think, all the participants got a couple of timed runs.
Another rethink was required. Mick decided that sensor gear could not be made to work much better so we came up with the idea of using the cameras as before, but running them to a central 4 way split screen monitor which was to be recorded on VHS video tape (12 volt VCR and cameras). The third segment of the screen had a start boat camera aimed to pick up the sail number from a better angle and in the fourth segment was a camera filming a running stopwatch display. The idea was that we could run the video back after the event to get the start and finish times of every run and not miss anything. Unfortunately we were back to using very long cables to the cameras, but that worked OK. Before the event event started, we realised that it would be an extremely time consuming and boring job to go though the tapes to get all the speeds, and we realised we needed some more timely feedback on each run. So, in the event, we had a few people sitting in the timing boat with stopwatches, manually timing each run via the screen displays and writing down the speeds. This worked so well that we only used the tapes a few times to seperate close runs and validate the best speeds. We used this system successfully for the remaining events and then ran out of enthusiastic workers so the Sandy Point speed events ended until the GPS revolution came along and solved almost all the previous problems.
Interestingly, my understanding is that a similar system is used to this day for the Luderitz video timing, although they can now confirm the runs by the video MUCH faster during the event. The actual accuracy of the Luderitz video timing is only marginally better (at best) than the best hand held GPS's devices (with SDoP and excellent reception) we use today. This was confirmed by Manfred Fuchs (who also had a big part on the design of the video timing) with experiments we did at Luderitz using twin 10Hz ublox 6 based loggers, and GT-31's, and correlating scores of runs with the offical timing gear results. My more recent test observations indicate that the current 5Hz GW-52/60 (with good reception) and 10Hz ublox 8 based GPS's are significantly better than the ublox 6 based loggers we tested then. Note: there is always an 'error margin' with any measuring device, WSSRC approved video gates included.