© Robert Fenwick Elliott 2005-2006
What causes a miss?
A lot of pretty good croquet players are no more accurate roqueters than average; they achieve their advantage by tactics and croquet shots. But the ability to roquet well is still highly desirable.
The accuracy required to roquet a ball at the other side of a croquet lawn can be calculated.
The size of the target
A croquet ball is 3 ⅝inches in diameter. The striker’s ball will hit a target ball if its centre is headed anywhere along that diameter, or half a ball’s radius to either side. So the effective target is 2 balls’ width, or 7 ¼ inches.
The allowable angle
The maximum deviation from a perfect rush that will still hit a target ball obviously depends on the distance away of the target ball:
Reasons for missing
There are several reasons why we sometimes miss roquets
These are all mechanical reasons; we are not here trying to list the reasons for the reasons (eg the lawn may be uneven because of trees, we may twist the mallet during the swing because we lift our head etc)
If the mallet head is not lined up to the target before the swing starts, you are likely to miss (although some – usually not very good – players are remarkably adept at aiming in quite the wrong direction and then lurching back more or less on line during the swing. Not recommended).
Many people advocate stalking. Most people find that sight lines on the mallet head help; certainly the longer the head the easier it is to line up.
It helps if the cross section of the shaft is octagonal, or square with rounded corners, since the hands then provide additional information to the brain as to the direction of the mallet. Round is not good.
The striker’s ball leaves the mallet head perpendicular to the face of the mallet. So it does not matter much if the direction of the swing deviates a little from direction of aim, but it does matter hugely if the mallet head has rotated during the swing.
It helps to have a mallet with a high moment of inertia around the shaft, since the higher the moment of inertia, then the less the angular effect of any given inadvertent torque applied by the striker’s hands during the swing.
An octagonal (or square with rounded edges) shaft will help, since it enable the hands to provide additional information during the swing.
A more lively (elastic) head will help also, since less head speed is needed to achieve any required more ball speed. As any golfer will tell you, the higher the head speed, the more difficult it is control the swing.
If the centre of gravity of the mallet head is moving on a line to either side of the centre of the ball, then mallet head will twist. A part of that twist will occur during the millisecond of contact, and will cause the ball to go off line. After the contact, the mallet head will continue to twist during the follow through phase of the swing (by as much as 20o or so in some cases), which is too late to affect the ball, but which is a sure tell-tale sign of off-centre hitting. Alternatively, off-centre hitting can be detected by using carbon paper, or wear patterns on the mallet face, or just by the feel of the mallet in the hands and the sound of the impact.
This is perhaps the biggest single cause of missing, although it is hard to unravel from the twisting of the mallet during the swing, in that they both tend to be caused by errant movements of the head or upper body during the swing.
A high effective moment of inertia is excellent for reducing the effect of off-centre hitting (link to explanation of moment of inertia).
A shift in weight distribution from the shaft to the head will also help, in that it will increase the moment of inertia of the whole mallet around the point (normally a little above the top of the shaft) at the centre of the swing.
The effects of an uneven lawn can most clearly be seen early in the morning when there is dew on the ground on which the ball leaves a trail. The deviation is at its greatest when the ball is travelling at its slowest.
If the unevenness is constant (such as where the lawn is on a regular sideways slope) the effect can be illustrated. Take the case of a lawn which decelerates the ball at 1 ½ ft sec-2 and a slope which accelerates a moving ball at 1/100th of that rate sideways. A player shoots straight but slowly – at 16 ft sec-1 - at a target ball 26 yards away (eg from the north boundary to the south boundary), so that his ball would stop after 30 yards. By the time the ball reaches its target, it will have deviated by 9” – ample for a miss. Another player shoots 30% faster – 21 ft sec-1; his deviation will be only 3½ inches, so he will hit.
So even a fairly modest increase in ball speed can fairly dramatically reduce the risk of missing because of unevenness in the lawn. A lively mallet, with good elasticity, will produce a faster ball speed from any given swing. Swinging more vigorously will also work, but that carries the penalty of less control, and hence greater risk of twisting or off-centre hitting.
Grass tend to grow in clumps, and weeds even more so. If there is such a clump more or less under but slightly to one side of the player’s ball, then it can produce a deviation, especially if the player hits downwards.
Unless you live in a hurricane zone, you are unlikely to see a stationary ball being moved by the wind, because the wind is not forceful enough to overcome the resistance of the grass. But once a ball is sliding or rolling, then that resistance falls away, and a cross wind can produce a deviation.
The essential equation is the same as the unevenness of the lawn – the moral is try to increase ball speed.
Some theory underlying all of this can be found on our Basic Theory of Dynamics pages.