THE EFFECTS OF SLOPING COURTS CONTINUED The main effect of sloping courts is on the hit rate for longer shots, so the chart below focusses on those in the range 15m to 30m – from the length of a short li' shot up to the
improve their shoo7ng abili7es than to a8empt these complex adjustments. The other, normally less cri7cal, effect of an overall slope is on a player’s ability to land the ball on a specific target spot. Suppose that that spot is 20m away: how much will the ball dri' from its intended line on its journey there, for different degrees of slope, and how does that compare with the errors arising anyway from inaccuracy in the stroke itself? In this case, the player faces the full effects of the slope because the ball follows the en7rety of its curved path before reaching the target spot. Suppose the ball is struck on our 12 second court with sufficient force to reach a spot 20m away. It will dri' by a li8le over 0.3m on a 2 in 1000 slope, and pro rata for different slopes and distances (so the dri' to a spot 5m away on a 4 in 1000 slope will be about 0.15m). Dr. Grundy’s average player should be able to land two thirds of their single ball shots within 0.4m of the target spot at 20m, so the effect of the slope in this case is broadly comparable with the inaccuracy of their shots. But this dri' is the same for everyone, so it will lessen the advantage gained from high posi7onal accuracy. If the average player gets lucky, they may even end up exactly where they intended. That is less likely to happen for the accurate player, whose strokes will be more 7ghtly clustered around the wrong spot. Ge9ng the strength of the shot right also ma8ers, of course – and precise rushes or pin‐point posi7onal shots will require accuracy of both direc7on and strength. But over shorter distances, local varia7ons in the court – its humps and hollows – rather than its overall slope will generally be the dominant factor. They can be par7cularly no7ceable near the boundaries or close to hoops, where maintaining a flat surface is a constant challenge for the groundsman. Star7ng from a good overall level obviously makes it easier to deal with these tricky areas. So far, so hypothe7cal. Whether the overall slope of a court ma8ers in prac7ce depends on the extent of the slopes one is likely to be faced with on actual croquet courts. The chart below provides some prac7cal context. It plots the overall N/S (ver7cal axis) and E/W (horizontal axis) slopes of the seven courts at my local club, again in units of mm per metre, from the perspec7ve of someone on the South boundary (one of these courts has a different orienta7on – its South boundary corresponds with the East boundary on the other six). There are areas within these courts, and close to some boundaries, where the slopes may be more no7ceable – and which can be studied on the contour maps we have posted in the clubhouse and on our website. But they are certainly level enough for these overall slopes to be of li8le consequence. Examples of other club court surveys available to me show overall slopes of as much as 5mm per metre. These would certainly have a material effect on a crack shot’s accuracy and so would be less than ideal for top flight play. Con nued on page 14
full length of the court. Again, the court speed is taken to be 12 seconds. The central line plots the overall average hit rate (ver7cal axis) for the players Dr. Grundy observed, for different degrees of slope (horizontal axis – units per 1000); the upper and lower lines are for players twice and half as accurate as that average, respec7vely. Dr. Grundy’s sta7s7cs will have come from shots on courts which must also not have been perfectly level, so they will tend to understate accuracy pure and simple. But they do at least serve to illustrate the likely rela7ve importance of the slope for different groups of players. These results show that, for modest slopes (undetectable by eye), the hit rate is not much affected by the slope. But, as the slope increases, the hit rate of the crack shots starts to fall off quite markedly: they are too accurate for their own good. Indeed, once the slope reaches 8 in 1000, the average player’s inaccuracy becomes an asset and they are in fact more likely to be successful at long shots than the crack player (they would already out‐perform them at 30m when the slope reaches 5 in 1000). So if the slope of the court is sufficiently severe, hit and hope may indeed become the best strategy! This ‘levelling down’ is the basis of the case for wan7ng to play against the crack on an indifferent court. There are analogies with the ques7on of whether to aim at the centre of an imperfect double or at one of the two balls (see Allen Parker’s ar7cles in the Winter 1977 and Spring 1978 issues of the Gaze8e for a thorough analysis). It all depends on how far away it is, and how good a shot you are. The slope would of course be obvious well before it reaches 8 in 1000, so it might be thought that the crack could simply ‘aim off’ to regain their advantage. But it is not that simple, because the required correc7on depends not only on the slope itself but also on both the strength with which the ball is struck and the distance to the target. In this par7cular case, the crack would need to aim off by rather less than a full ball at 15m but over three balls’ width at 30m; and on a 5 in 1000 slope the adjustments would be half a ball and two balls’ width. Mere mortals would be be8er advised to
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