Four makes of croquet ball now have C.A. Championship Approval and may be used in C.A Tournaments. Players and clubs may welcome publication of some comparative results from the Approval and other tests to inform play or purchase decisions.
The four types are the Barlow GT, Dawson 2000 International, Sunshiny, and Willhoite Xtreme (U.S.A.). The tests for Approval aim to ensure that balls are suitable for use in Championships: balls are tested in respect of weight, roundness, rebound and milling and limits are set on the variance in diameter and rebound for single balls and for all the balls in the set submitted. Details of the tests and suppliers' addresses are given on the CA website. Dawson has separate Approval for both 1st and 2nd colour sets; the other makers have so far submitted only 1st colours. Test measurements are made with relatively simple apparatus (in which, for example, rebound heights are determined by eye), so absolute accuracy is not claimed. The results should, however, provide a reasonably sound basis for comparison.
A simple test for roundness, which emerges from the test measurements is the difference between a ball's maximum and minimum diameters. Results were typically as follows:
Barlow 0.6mm; Dawson 0.3mm; Sunshiny 0.5mm; Willhoite 0.2(5)mm
Note that 1/32 inch = 0.8 mm
There was very little variation between different balls in any of the sets.
All makes were accurate in weight - all within 5g of 1 pound (454 g).
Rebound heights are measured on 6 points of each ball: 4 nodes in the milling pattern (one of which bears the logo) and two poles which have a checkerboard pattern. The average rebound heights were as follows:
Barlow 90.7 cm (19 deg C)
Dawson 91.5 cm (19 deg C, 1st colours), 92.4 cm (25 deg C, 2nd colours)
Sunshiny 84 cm (22 deg C)
Willhoite 87.5 cm (20 deg C)
The rebound height may vary somewhat over the six points for a single ball. Typical results for the range of variation were as follows.
Barlow 3 cm, Dawson 1 cm, Sunshiny 7 cm, Willhoite 2 cm
Barlow, Dawson and Sunshiny patterns were regular; Willhoite, though complying with the test criterion (upstands wider than grooves), had some uneven spacing which would presumably be rectified in a production model of the ball.
Our attention has focused principally on the Barlow and Dawson balls, since both are easily available here (Barlow from John Beech, Dawson within 7 days from Australia); as yet, there is no UK supplier for Sunshiny and as far as I am aware, the Willhoite ball is not yet in production. The test results show the Barlow GT and Dawson 2000 International to be very similar in average rebound, with the Dawson having more consistent rebound over the six test points of the ball, possibly because it has somewhat shallower milling. Both are made from polyurethane: the Barlow has a small internal cavity whereas the Dawson is solid. Experience of Barlows here and elsewhere and of earlier Dawsons made from the same material as the International shows that both makes have good durability. The Barlow ball sometimes has a small bias that can be detected by flotation in brine. Normally such bias is too small to have a noticeable effect in play. Flotation tests did not detect any bias in the Dawson ball.
To determine how the test results relate to playing characteristics, two highly ranked players (Colin Irwin and David Maugham) were asked to perform identical shots (using 'Barlow technique') alternately with the tested sets of Barlow and Dawson balls, so that comparative distance measurements could be made. As expected from the similarity in the rebound heights, the balls were very similar in play with no reliable difference being detected in straight half-rolls, split rolls or straight rushes. The Dawson forward ball travelled relatively further (10 - 15%) in long drives or stop-shots and gave slightly greater separation in a straight full-rolls. The players had no difficulty in making adjustments to compensate for the small differences encountered. No difference in 'pull' was detected in either long split shots or in short 'peeling' shots.
A less structured assessment of the Sunshiny set indicated that the lower rebound height translates to a noticeably less lively ball in play.