OxfordCroquet Logo

Dr Ian Plummer

Donation Button

http://www.oxfordcroquet.com/tech/hoops/index.asp
Technical
CA Hoop Tests – March 2013

Note: this is a DRAFT report, prepared by Martin French.  From these tests reported here, it was felt:

  • Further tests were needed with a range of hoop designs made in stainless steel with no surface coating, as the coating seems to be a major factor in making hoops easy to run

  • The ramp used in many of the tests may well be putting too much top spin on the balls, producing a "hoop stroke" that a real player cannot match.

Hence, these tests were not considered conclusive and have only served to inform our next round of testing.  The following draft report is offered in case it is of interest, but should not be regarded as the last word on any of the points considered.

Executive summary

In recent years, there has been a growing desire for hoops that present a greater challenge for Association Croquet Championship (and A Class) play, even in our wettest UK summers.  To many, the easy hoops and slow lawns after a period of rain remove the advantage that accurate break play should bring in top class Association Croquet – if we could restore that premium, it would be of great benefit to the sport.  This report describes some tests conducted by the CA Equipment Committee on a number of novel or prototype hoops, all hoping to produce more demanding hoops in "easy" conditions. 

The results were less clear cut than would be liked – it seems in typical damp loamy soil, nothing so far trialled makes a large difference in the challenge provided by a hoop.   However three factors seem to help with increasing the challenge:

  • An un-coated upright – which implies stainless steel

  • Square "parsnips" rather than round carrots

  • Square rather than round uprights

Two factors that didn't seem to help:

  • Below-ground fins

  • Ever-narrower settings – there was no measurable difference between 1/32" and 3/32" hoops.

It seems nothing found so far is as good as a prolonged dry spell (with no lawn watering) if you want challenging hoops.

Conclusions

  • Perhaps the most important conclusion is that the differences between these different hoop innovations seemed smaller than the differences to well set hoops caused by different court conditions (soil moisture contents).  In this typical damp ground, none of the trial hoops magically provided a hoop as challenging as ordinary hoops well set in baked-hard dry lawns in a good summer.

  • The fins of the Superhoop may have benefits on a constructed court of layered sand, but were not practical nor effective in typical UK loam courts.  Installing the hoops and removing them for mowing would be extremely difficult, and the hoop on test was inferior to all the other hoops tried on a loam court, possibly because the setting was looser in the ground from the start.

  • The change which had the most dramatic effect was to use uprights which were square in cross section.  These look daunting.  One side of our two test hoops with square uprights appeared to be the standard square steel stock, with little or no chamfer on the edges of the uprights.  The other side had a small chamfer of maybe 1.5mm, and yet these hoops performed very differently from either side.  The exact amount of chamfer must be very critical, and further tests over time would be needed to see if the little or no chamfer might cause ball damage.

  • Although the objective evidence is patchy, we are fairly convinced that parsnips can be set more firmly in the ground and maintain their setting for longer.  They seem to restrict the offset (= "inaccurate hoop stroke") with which a straight hoop may be run and may possibly restrict the angle of approach.

  • Putting all this together, our "best buy" for a hoop that should provide more of a challenge in typical UK loam courts in damp conditions would include: square parsnips and plain (un-coated) square stainless steel uprights. 

  • It is unfortunate but the very attractive smooth powder coating in use on some new hoops today seems to make them significantly easier to run.

  • Reducing the gap between ball and hoop makes surprisingly little difference to the resistance the put up, at least in damp soil.

  • It has been speculated that greater mass may make hoops more challenging.  However, perversely a number of  test hoops with thicker uprights seem no more difficult and perhaps even easier to run.  This was supported by finding the Superhoop, with the thickest uprights on test, being the easiest hoop to run.  Maybe the larger diameter of thick uprights helps guide the ball through, or maybe balls deform more and 'grab' at thinner wires?

Objectives

Narrow hoops set in firm, dry ground provide a good challenge for top players.  But after periods of rain, even hoops set to 1/32" gap can seem "trivial".  An ideal new hoop type, even when set in soft ground, should present a proper challenge and reward the more accurate play of the best players, while penalising inaccurate approaches and poor hoop strokes.  It is not the intention to make an "impossible" hoop, just to restore the premium for accurate break play that can be lost when the conditions are "easy".  By creating just a couple more 'opportunities to break down' per game for an inaccurate player, would help restore the premium for good play.

The hoops tested all contained ideas aimed at providing this ideal:

  • More effective carrots

  • Thicker or different shape uprights

  • Different surface finishes

The objectives of the tests were to tease apart which of these innovations were actually making the hoop more difficult to run, and which seemed to make little difference.

Hoops tested

See the table in Appendix 1 for details.

Hoop 1 – our 'reference hoop', a standard Aldridge championship hoop.  Welded steel construction, white powder coating.  Round carrots and round uprights.

Hoop 2 – standard Aldridge round carrots but with square section uprights.  Welded steel construction, white powder coating.  On one side, the only slight bevel on the corner between two faces of the upright was the natural shape of the steel stock (called Hoop 2A).  The other side, a small bevel (about 1.5mm) had been ground between two faces (called Hoop 2B).

Hoop 3 – standard Aldridge round uprights welded onto square carrots ("parsnips"). Welded steel construction, white powder coating.

Hoop 4 – square parsnips and square section uprights.  Welded steel construction, white powder coating.  On one side, the only slight bevel on the corner between two faces of the upright was the natural shape of the steel stock (called Hoop 4A).  The other side, a small bevel (about 1.5mm) had been ground between two faces (called Hoop 4B).

Superhoop – US hoop developed specifically for use in constructed sand courts – where the court is built up from a shingle and gravel base, through layers of finer aggregate until the upper layers are sand with a thin loam top layer containing the turn.  Welded thick stainless steel bar, natural finish.  No carrots, but 4 wide fins welded around the lower part of each upright.  See note about setting and removing the Superhoop below.

Atkins Quadway – novel NZ design with square parsnips, and self-colour stainless steel uprights which can be rotated and fixed in the crown to give different width settings.

Note about settings

While each hoop's "free air width" just below the crown and at half-ball height was measured, in practice, every hoop was set using an Oakley hoop clamp (as sold by the CA Shop) in new holes to the same setting of 1/16" (except where noted otherwise), with a tolerance of 1/64".  Hoops were moved to new holes for subsequent batches of tests. 

While the width at the top of the uprights of the Quadway may be adjusted with the aid of an Allen key, this on its own makes precious little difference to the width in the ground, but could allow a consistent width to be created all the way up to the crown that might affect jump shots.

Note about the Superhoop

This hoop seems unsuitable for typical UK loamy and stony soils.  It took 6 minutes of continuous pounding with a heavy mallet to get the Superhoop in the ground.  It was noticeably less firm than all the other hoops, perhaps because the integrity of the turf had been broken by the fins.  It is not practical to adjust the width in the normal ways – the width is whatever it ends up when you remove the clamp.

Removing the Superhoop is very difficult indeed.  An accurate template must be constructed and a car jack used to pull the hoop up away from the template – whose purpose is to hold the surface of the ground together during extraction.  Removing the hoop took several minutes and despite the template, a chunk of turf about 9cm x 7cm x 6cm came out stuck between the bottom of the fins.  It left significant damage to the court.

Testing set-up

Two test rigs were used:

Ramp1. A 2m Ramp, raised by around 40cm, such that a ball would travel around 6m across a typical lawn.  The design of the ramp meant that the balls were delivered with a degree of top spin – something some players strive for in hoop strokes.  (The ramp was in fact two rails, around 45mm apart, so that as the ball ran down these rails, its angular velocity at its periphery was greater than its forward motion.)  All the tests with the ramp were on straight hoop shots, but with various offsets from the hoop centre-line.


PPPP2. the Pidcock Peeling Plank was used (PPP) to shoot balls at angled hoops, and at various offsets to the near wire (-1/8" through to +3/16").  

All the tests with the PPP were at angled hoops of between 25° and 50°.  The angles quoted are measured with respect to the 'normal' to the hoop – so a straight hoop would have an angle of 0°.

With the Ramp, batches of ten tests were conducted from each position; with the PPP, five peels were conducted from each angle.

Critique of techniques

After 30 or 40 shots, the balls created a very small dent at the foot of the Ramp and also a rabbit run in the jaws.  This dent was perhaps throwing balls off-target.  Out of a batch of shots, there would be a wide variety of distances travelled.  It was also observed that a 'track' developed after a few shots, which reduced the resistance to subsequent balls – in several batches of tests, there were some of the longest outcomes late in the batch.

The tests with the PPP suffered a different problem – that having lined up the two balls for the peel, it had to be struck with a mallet manually. So there was a large variation in force of stroke.  Slower strokes seemed more likely to drift off target and into one or other wire, compared to firm strokes.

The consequence for both test rigs was the variations in outcomes across the batch of shots (5 or 10) was large, and may mask any real differences between one hoop and the next.  Perhaps the most fundamental problem is that it isn't feasible to test the range of typical hoop strokes in such rigs: the strength, spin, follow-through, real-world inaccuracies in aim, and so on.

Test conditions

Unless stated otherwise, all tests were conducted with the hoop set in new holes and with a gap between ball and hoop of 1/16".

Balls were Dawson 2000.

The ground was damp but not saturated – it seemed firm but plastic, and typical of a summer lawn in the UK except during a prolonged dry spell.

The soil was a typical UK loam.  The top 1" was quite sandy due to repeated top-dressing.  Below that, the soil was a reasonably sticky loam with occasional stones.

Lawn speed was judged to be medium, though was not measured in Plummers.  The lawns had been double-cut the day before and had been in play throughout the previous winter months.

Test results

Test 1 – initial assessment of maximum running angle (PPP)

A more challenging hoop would give a smaller maximum angle from which it could be run.

Hoop

Uprights

Carrots

Offset from near wire

Max Angle (degrees from normal)

1

Round

Round

0

50

2A

Square

Round

up to 1.5mm

45

3

Round

Square

0

45

4A

Square

Square

up to 1.5mm

45

Superhoop

Round

Finned

0

50 *

Quadway

Round

Square

0

40 critical

45 rejection

* Although in a new hole, this hoop remained wobbly in the ground and was surprisingly easy to run as a result

Potential Finding: surprisingly small differences, especially with the square uprights which looked formidable.  Were the parsnips of the Quadway and Hoop 3 "worth" 5° of additional challenge?

Test 2 – effect of offset (PPP)

Hoop

Uprights

Carrots

Offset from near wire

Max Angle (degrees from normal)

1

Round

Round

0

50

1

Round

Round

8mm

45 *

* At 8mm offset, the ball be bullied through with a forceful shot, but would stop in the jaws with a normal stroke

Potential Finding: it was most surprising how much offset could be applied before balls ceased to run the hoop. This is offset with respect to just clearing the near wire: it seemed to be often possible to run the hoop with an offset from -1.6mm up to +8mm.

Test 3 – initial assessment of maximum offset on straight hoop strokes (Ramp)

The ramp, set up at right angles to the hoop, was moved progressively more and more offset to one side, to find how 'forgiving' the hoop was of poor hoop strokes.  The point at which balls either failed to run or only grovelled through was recorded.

Hoop

Uprights

Carrots

Max offset from centre line

1

Round

Round

16.25mm

2A

Square/ no chamfer

Round

8.25mm *

2B

Square/ chamfer

Round

14.5mm

4A

Square/ no chamfer

Square

8mm *

4B

Square/ chamfer

Square

15mm

Quadway

Round

Square

12.5mm

* Tests on 2A and 4A were conducted with the hoop in the existing holes (for 2B and 4B) but now from the other side.  As there was a slight slope and this was now up-slope rather than down-slope, a check was made on 2B turned around so that was also up-slope: this gave a result of 13mm instead of 14.5mm when down-slope.  So the effects of slope were much smaller than the difference between hoops 2A and 4A, and all the other hoops.

Potential Finding: The Quadway seemed slightly more challenging (but see Test 6 later).  The square uprights of Hoops 2A and 4A, which differed only from 2B and 4B by the latter having very slight chamfers on the edge between the faces, were considerably less tolerant of off-line hoop strokes.

Test 4 – Subjective assessment of resisting abuse

Hoops 1 and 3 (same round uprights, on either round carrots or square parsnips) were 'hacked at' repeatedly.  20 very hard stokes were played from about 45cm away, at around 30° to the normal.  Some strokes ran, some rejected, for both hoops.

Hoop

Uprights

Carrots

Outcome

1

Round

Round

Initial setting of 93.7mm widened to 93.9mm and hoop became slightly looser in the ground

3

Round

Square

Initial setting of 93.7mm widened to 93.8mm and hoop became slightly looser in the ground – perhaps a little more so than hoop 1.

Potential Finding: It seems likely the small difference in widening observed was as much due to differences in the 'free air width' of the hoop or to the odd stone below ground, as to the different properties of carrots or parsnips.  We did not find the greater resistance to bullying we hoped for from the parsnips.

Test 5 – Further comparison of Quadway and equivalent Aldridge Hoop 3

The Quadway and Hoop 3 appear to be very similar in construction (square parsnips and round uprights of the same diameter), and yet some of the measured results had been quite different.  Why?  Perhaps it was down to different masses and surface finishes?  It was decided to repeat and extend some of the tests on just these two.

Comparison

Quadway

Hoop 3

Weight

2532g

2390g

Balance point

55mm from top of parsnip

60mm from top of parsnip

Parsnip size

Slightly smaller

Slightly larger but contains a void

Free air gap at half-ball height

93.5mm

93.3mm

Uprights finish

Stainless steel

Powder coated steel

Max angle where no balls go through (PPP)

42°

50°

Max offset (PPP)

Can add 9.2mm offset and some balls will still just run through

Can add 6mm offset and some balls will still just run through

Max offset (Ramp)

The limiting offset, at which balls cease to run through a straight hoop, is 12.5mm

The limiting offset, at which balls cease to run through, is 18mm (this was repeated in new holes and confirmed at 18.75mm)

Potential Finding: in most regards, the Quadway was a more challenging hoop to run than Hoop 3, and yet they seemed very similar.   It was speculated that perhaps the smooth powder coating surface finish on the Aldridge was helping balls through.  It was decided to scrape the powder coat off of the running area of hoops 3 and 4 for the remaining tests, to see if this could be confirmed.

Test 6 – Extended offset tests using Ramp: Quadway, Hoop 3 and Hoop 4

With the surface coating removed from Hoops 3 and 4, an extended set of tests running batches of balls down the Ramp and measuring how freely (= far through) they ran.

Quadway

Offset

10 tests, distance through ball travelled (cm)

Average (cm)

0

500, 440, 460, 470, 430, 530, 550, 540, 560, 620*

510

5mm

310, 530, 380, 420, 370, 570, 580, 600, 610, 460*

483

10mm

320, 390, 420, 450, 160, 270, 450, 430, 240, 370

350

12mm

220, 250, 270, 260, 180, 170, 230, 260, 230, 80

215

15mm

20, 60, 160, 160, 160, 40, 30, 90, 160, 170

105

* note the "tracking" effect, where the longest runs all seem to come later in the batch

Potential Finding: this illustrates the problem with these tests, despite careful execution.  All 10 attempts at 15mm offset ran through the hoop – yet in Test 3 we had determined that 12.5mm was the maximum offset that would still run through the Quadway.  Perhaps the tracking effect developed by the earlier batches facilitated the later batches running at "impossible" offsets?

This testing approach does however show an increasingly inaccurate hoop stroke results in the ball running decreasingly far through the hoop, despite having the same initial energy.

The other hoops were then tested using just the 15mm offset for comparison, and to reduce the chance for tracking to develop.

Hoop

10 tests, distance through ball travelled (cm)

Average (cm)

31

10, 20, 25, 30, 70, 10, 25, 25, 30, 50

29.5

Quadway2

0, 30, 35, 30, 50, 30, 30, 50, 55, 185

49.5

33

0, 0, 0, 10, 20, 15, 20, 20, 20, 85

19

4A4

0, 0, 0, 0, 0, 15, 0, 0, 0, 0

1.5

4B5

7, 20, 25, 0, 0, 0, 15, 20, 40, 65

19.2

1. inadvertently set at 3/32" gap

2. in new ground and holes to avoid the tracking effect; just over 1/16" gap

3. repeated in new holes, gap reduced to just over 1/16"

4,5. gap 5/64"

A club hammer was taped to the crown of the hoop at the end of the 4B test, to see if the extra mass made any difference, but it didn't appear to.

Potential Finding: With the powder coating removed from the running areas of Hoops 3 and 4, the more challenging results found previously for the Quadway were now over-taken by Hoops 3 and 4.  Hoop 4A with no chamfer was particular resistant to balls running at this offset.  These results show that the difference observed in earlier tests between the Quadway and the similar Aldridge trial hoops was more to do with the powder coating finish than the underlying construction.

Test 7 – Comparison of Hoop 4A with Hoop1 (Ramp and PPP)

A final comparison was made of the most challenging trial hoop, 4A with the powder coating removed, versus Hoop 1 (a standard Aldridge championship hoop).

Ramp

Hoop

Offset

10 tests, distance through ball travelled (cm)

Average (cm)

11

15mm

10, 20, 25, 25, 25, 25, 30, 40, 50, 65

31.5

4A2

15mm

none ran the hoop

0

ditto

10mm

0, 15, 15, 20, 50, 30, 30, 40, 70, 105

37.5

1. 1/16" gap, measured at 93.1mm

2. 5/64" gap, measured at 93.4mm

When it was realised the 4A batch had been run with a wider hoop setting, they were repeated with the hoop set in new holes to 1/32" – but this made no material difference to the outcome.

Potential Finding: Whereas a standard hoop (Hoop 1) would accept a shot up to 15mm off-target, with the square un-painted uprights and parsnips of Hoop 4A, this reduced to 10mm.  So 4A now presented more of a challenge.  As suspected, changing the width of the hoop setting from over 1/16" to 1/32" made no material difference.

PPP

Hoop

Offset

Limiting angle at which balls would not generally run hoop (degrees)

11

0 mm

45

4A2

0 mm

45 (40 except with bullying)

4A3

0 mm

no material difference to same hoop at wider setting

1. measured at 93.5mm

2. measured at 93.4mm

3. re-set and measured at a tight 1/32", 92.3mm

Potential Finding: So despite square uprights, parsnips and no paint on the uprights, there was no measurable difference between Hoop 4A and the reference Hoop 1.  Again, changing the width of the hoop between 1/16" and 1/32" made no measurable difference either.

Martin French comments (Aug 2013):

"... a couple of years ago I tried and tested hoops with a chamfered or facetted upright.  I took a normal hoop and milled a flat at 35°, then 45° and finally 55° to the direction of (straight running).   The flats were maybe 10mm across and extended from the bottom to the top of the uprights.  You could measure the increasing difficulty using the Pidcock Perfect Peeling Plank or the ramp, both compared to a normal hoop and as the angle increased.  But, when we then made a set of 6 and took them around a few events, including the Chairmans and Mens, it turned out the differences were much less noticeable "in the field".  Not a sufficient difference to warrant asking clubs to reinvest.

We need some new ideas I think.  Over the past century, lots of things have been tried, but the end results vary more due to lawn conditions, soil type and amount of rain than they do due to the cunningness of the designs.

I think the combination of square carrot ("parsnip" as Alan Pidcock likes to call them) and unpainted upright may be about as much as we can achieve without some new miracle approach to the problem – these are worth testing more carefully.  I think the Egyptian championship hoops are fantastic for GC – and they have two carrot lengths depending on whether the soil is silt or sand – and it would be interesting to test those in English soils to see how they worked for Association Croquet.  I hope the CA Equipment Committee might be able to try both these directions during the coming winter. "

 

Appendix 1

CA Equipment Committee hoops trials - Spring 2013

Hoops

Description

Weight (kg)

Height (mm)

Half-ball width (mm)

Uprights (mm)

Finish

1

Standard Aldridge

2.60

520

94

 

Powder coat

The half-ball width was measured as new and in air

2A

Round carrots, square uprights - no chamfer

2.82

515

93

 

Powder coat

The square uprights resulted in a heavier superstructure

2B

Round carrots, square uprights - small chamfer

2.82

515

93

 

Powder coat

The small chamfer was around 1.5mm only

3

Square parsnips, round uprights

2.39

520

93.3

 

Powder coat*

 

4A

Square parsnips, square uprights - no chamfer

2.66

515

93

 

Powder coat*

The square parsnips were hollow, so weighed 6-10% less than a round carrot

4B

Square parsnips, square uprights - small chamfer

2.66

515

93

 

Powder coat*

The small chamfer was around 1.5mm only

Superhoop

Large diameter welded rod with fins below ground

 

 

 

 

Stainless steel

 

Quadway

Adkins Quadway, square parsnips

2.53

 

93.5

 

Stainless steel

 

* For some later tests, the powder coat was scraped off to reveal a plain steel finish

Empty fields - data still to be collected.

Author: Martin French
All rights reserved © 2013-2017


Updated 28.i.16
About, Feedback
www.oxfordcroquet.com/tech/hoops/index.asp
on www.oxfordcroquet.com
Hits: 5025