Thursday, 12 April 2012

Lap Charts

Following my post about getting started in commentary, inevitably, someone asked about lap charts. In the old days, the raceday programme that you bought when you were at the track always contained a blank lap chart template, and it was this that got me started in the first place. The image below is from a Thruxton programme in 1977 - unfortunately the BARC lap charts only allowed you to record the cars in the top six positions though.

There is a book called "How to Watch Motor Racing" by Stirling Moss, (it's available second hand from Amazon) and although it is terribly out of date now, it is a jolly good read. In it are (amongst other things) instructions about how to keep a lap chart. In essence, all you do is to write down the numbers of the cars each time they pass you. Write them down in a column, starting a new column each time the leader comes past. Here is a photograph from the relevant page in Stirling's book - you can see how number 7, having led the race until just after half-distance, drops out, and number 17, starting from the back, comes through to finish on the podium.

This is what I call a "block chart" - it is a term I learnt from Mike Eyre, a chief RAC timekeeper in the 1980's. It is also sometimes these days called a "position chart", in that it gives you the position of each car on each lap. If you look on the TSL Timing website, they provide an electronic version of this after most major events in the UK where they are officiating.

This chart is very useful, and relatively easy to produce for short races. It helps if you can write quickly, legibly, and in a straight column, without having to look down at what you're writing.

Note though, that when the leader starts to lap the backmarkers, you have to record the backmarker in a previous column - he has not, after all, completed the same number of laps as the race leader. This is where it gets difficult with a long-distance race: the leaders will lap slower cars many times and even the mid-field runners will lap those at the back. Here is my block lapchart for the 1000km race at Brands Hatch in 1986.

This is just the first 50 or so laps of a 236 lap race - so there is a lot of paper to the right of the photograph!

Things to note (you might have to expand the photo):
  • horizontal (green) lines dividing the positions after every five cars... this is useful to quickly be able to see who is running in, say, 12th place.

  • vertical (green) lines - these show the start and end of safety car periods. As the race goes on you can observe how these lines spread across several laps, showing how the field gets spread out as the backmarkers lose more and more laps to the race leaders.

  • circle around cars when they make a pit stop - apart from anything else, this also makes it easier to find when it rejoins, probably losing places as a result.

  • The trouble with trying to keep a block chart going is that you will often get three cars crossing the line close together, all on different laps, and by the time you have found where they all belong on the chart, another two cars will come past and you easily get lost.

    The answer is to have an assistant, doing a "running chart". This merely records the number of each car as it comes past, in the order that the cars are running on the track. Don't worry about which cars are a lap behind, just make sure that you record each car. Start a new column every time the leader comes past, just because it is a good check on how many laps are completed. In the early stages, of course, before the lappery starts, it will closely resemble the block chart, but as the race develops, it provides the raw data input required to facilitate the block chart. Indeed, the first time I enlisted a helper to do this, I ended up spending more time looking at the running chart than I did looking at the cars on the track.

    If you looked up TSL's website before (to look at a position chart) - look now for what they call a "Lap Chart", and look at the column containing the car number. This gives the order that the cars cut the timing beam, and effectively shows what the running chart looks like. Of course some columns are longer than others, depending who rejoins from pit stops, or whether the leader has stopped.

    So to summarise (for the benefit of Chris, who asked the question) a block chart shows you at a glance the position of each car, and how many laps they have all completed; whereas the running chart just shows the order that cars are running on the track.

    If you're quick, and have a stop watch, you can make notes on the running chart of the gaps between significant cars - this way you'll pick up who might be closing on whom, and whether a pass for position might be on the cards. Even with electronic timing, I still find a lap chart massively helpful, not only in following a race as it unfolds, but also to keep as a record of what happened.


    1. Paul,

      Thanks for the explanation.

      When I was younger and attended Formula 1 races etc, I used to keep a lap chart. With the standard of the PA systems at the various tracks (I'm talking about the 70's) it was essential.

      I still do for some races - if it's a 'short' race (say 3 hours) and I'm going to keep in my seat for the whole race, I'll do a chart.

      At the longer races, I like to walk round the track and see the action from various places and therefore depend on radio, headphones and the circuit commentator (or Radio Le Mans) to keep me up to date with what is happening.

      Thanks for the article on lap charts, and for the blog. Looking forward to listening to you at Le Mans.


    2. So where does 'time in the pits' data come from? A stop watch doesn't tell you if the car has pitted or how long that was. I'm sure that now this is computer derived data (although someone would have to record the car entering the pit lane) but considering that races have been won and lost on the basis of a few seconds a pit over 24 hours, this must have been recorded somehow?

    3. 'Time spent in pits' is either issued as information from the timekeepers, or is calculated, based on data from the timing system. Most circuit timing systems these days have (a) sector sensors laid at various (at least two) points around the circuit and (b) timing loops in the pit lane. This provides a 'pit in' and 'pit out' time (often there are timing loops along the pit lane as well, used to check whether cars are exceeding the pit lane speed limit).

      The time spent in pits comes from this element of the timekeepers system (usually not connected to the main 'lap timing' element).

      Of course, this means that the 'time in pit' includes the time spent driving to the car's pit from 'pit in' and then from the pit to 'pit out'. At Le Mans, this alone accounts for 23 seconds (at least), which means that the absolute minimum time spent in the pit will be about ten minutes, before any work (including re-fuelling) is done.

      Since there has not always been a 'pit lane' at Le Mans, this means that comparisions over the years are meaningless (and the pit rules have varied over the time that there has been a pit lane as well). The least total time ever spent in the pits by a finisher in the twenty four hours is probably a Monopole X84 in 1954, which according to contemporary records, spent just 5 minutes and 10 seconds at rest.

      None of this has anything to do with lap charts, so apologies for getting so far off topic.

      If anyone really wants an article about 'time spent in pits' - then speak up here!

      1. A time in the pits article would be fascinating. As discussed on here once before, the 'reliability' of cars over the years has improved for the front runners but I would love to know if it's improved for other classes. Understanding any trends in both pit time and reasons for unscheduled stops may point toward where development has been focussed and consistent weak spots on the cars.