9pinZ™ individual statistics

9pinZ™ scripting has been developed by ThornburyPump to present a skittles team's fixtures, results and individual statistics at a glance on a single web page. You just enter your fixtures and players on a spreadsheet at the start of the season, update players' scores after each game and email the updated spreadsheet to ThornburyPump. We upload the data to our server in a suitable format and 9pinZ™ scripts held on our server do all the tedious calculations and presentation automatically for you.

Successfully piloted on The Geordies website, we would like to share the scripts with a wider range of users and will host a results and statistics web page free of charge for the first few skittles teams to sign up.

Follow this link to see what your page could look like.

Swerve

Swerve only occurs while the ball is skidding. Once pure rolling has begun, the ball will move in a straight line - assuming that the ball has no bias and the alley is level. There are three components of spin, only one of which directly affects a skittler's ability to swerve the ball:

• About a vertical axis - will not affect the ball's trajectory along the alley but may come into play on collision with pins.
• About a horizontal axis across the alley (ω₂ radians/s) - this affects the transition from skidding to pure rolling and the ball's speed down the alley but has no direct impact on swerve.
• About a horizontal axis along the alley (ω₁ radians/s) - this is the component that creates swerve. Ceteri paribus, the greater the speed of delivery, the longer the length of time over which swerve can occur.

If a ball of radius r released at speed V is spinning on release, the angle through which the ball swerves (ψ) and the transverse movement (x) are given by C.B. Daish (Chapter 14 of The Physics of Ball Games) as follows:

tanψ = 2ω₁r / (7V - 2 (V - ω₂r))

x = ½ (µg sinθ) T²

where: tanθ = ω₁r / (V - ω₂r)
T = 2U / 7μg
and U² = (V - ω₂r)² + (ω₂r)²

As an example of the magnitude of the swerve which can be achieved, consider a 4½ inch diameter ball, delivered at 8 m/s along a 10 m alley, spinning at 1 revolution per second about an axis along the alley with a coefficient of friction of 0.3. Skidding will cease after about 5½ m where the transverse movement will be about 4 cm, increasing to 12 cm when the pins are reached. The overall swerve is only 1° but the potential impact of spin can mean the difference between hitting a pin and missing all.

Conclusions

Lessons from evaluating realistic ranges of speed of delivery and spin:

• Late swerve may be a reality but it is most likely to be due to a bias in the ball or an imperfectly level alley as the pins are approached. A vertical mismatch between boards is likely to have a significant effect.
• Attempting to spin a slow delivery causes swerve in the early stages of travel down the alley making control of the trajectory more difficult. For a given spin the transverse movement is inversely proportional to the speed of delivery, i.e. is disproportionately greater for slower deliveries. If the spin is proportional to the speed of delivery then transverse movement is approximately independent of delivery speed.
• If you have a natural tendency to spin the ball clockwise along the length of the alley don't stand on the right side to launch it! Likewise avoid the left side if you have a tendency to anti-clockwise spin. Otherwise the ball will tend to straighten on its way down the alley and impacting the pins at an angle will not be facilitated.
• In view of these conclusions, avoid deliberate spin in matches until your delivery is well practised!

Slide-roll transition

For pure rolling, the velocity of that part of the ball which is in instantaneous contact with the alley must be zero. This requires that the velocity of the ball along the alley should be perfectly balanced by the rotational velocity of the ball's surface at the contact point. Any imbalance will give rise to skidding, in which case a frictional force will operate, the ball's linear speed will decrease and its rotation will increase until the velocity of the contact point is zero and pure rolling is occurring.

The speed of delivery and initial spin are major factors in both time from release and distance down the alley before pure rolling is established. It is therefore also a dominant inluence on the ability to swerve the ball.

Assuming that the ball is not rotating on release, the time taken (T) and distance travelled (S) before pure rolling are given by C.B. Daish (Chapter 14 of The Physics of Ball Games) as follows:


T = 2V / 7µg ; S = 12V² / 49µg

where V is the speed of delivery (m/s),
µ is the coefficient of sliding friction,
and g is gravitational acceleration (m/s²).

The coefficient of sliding friction (µ) for wood on wood is between 0.2 and 0.5 depending on the conditions of the ball and alley surfaces. The lower value is appropriate to pristine balls on a newly laid and polished alley. A value towards the upper end of the range is more likely to apply to the conditions on our home alley. The gravitational acceleration (g) is relatively constant in the Thornbury area with a value of about 9.81 m/s² (although there is allegedly a significant mascon in the vicinity of Tytherington!) Observation of Geordies suggests that speed of delivery (V) is typically in the range 1 to 5 m/s perhaps as high as 10 m/s, occasionally 15 m/s, for Farmer Hall.

The following figure illustrates behaviour for a friction coefficient of 0.3. A ball launched at 5 m/s will slide for 2 m and will roll thereafter. A ball launched at 10 m/s under these conditions will be sliding for 8 m, i.e. most of the length of the alley.




Once pure rolling is achieved the linear velocity will be about 0.7V. The coefficient of rolling friction is between 0.002 and 0.05 and will not slow the ball significantly before pins are hit (or not).


In preparation for studying swerve it is convenient to write all equations in terms of dimensionless distances and times normalised to the point of transition from skidding to pure rolling.

The velocity (v) of the ball and its distance travelled as a function of time are given by:


v/V = 1 - 2t/7T when t<T; v/V = 5/7 when t>T
s/S = 7/6 (t/T) - 1/6 (t/T)² when t<T; s/S = 1/6 + 5/6 (t/T) when t>T

Performance, Zen and ‘flow’

To become an expert in any sporting discipline it typically takes 10,000 hours of practice during which the brain builds networks to enable automatic and precise responses.  I can’t have spent much more than 100 hours playing/practicing skittles which goes a long way towards explaining my mediocre performance. What if there were a way to speed up my learning process?  It seems that there is!  An article by Sally Adee on ‘Zen and the art of genius’ (New Scientist 4 February 2012) reports investigations into the role of an elusive mental state known as ‘flow’ which can allegedly slash the amount of time taken to master a new skill.

‘Flow’ is characterised by a feeling of effortless concentration with four key features which in the context of my bowling may be described as:

• Intense and focused absorption in which I lose all sense of time – not sure that I’ve ever experienced this!
• The sense that my activity is rewarding for its own sake - somewhat confused with the pleasures of a pint or two of real ale (autotelicity – the condition not the ale).
• Feeling that my abilities are perfectly matched to the task without feelings of frustration or boredom – very rare for me but there have been occasions when I knew from the instant that the ball left my hand that pins were going to fall in abundance.
• A sense that the ball is doing it all by itself – I rarely if ever experience this (automaticity).

I clearly have considerable needs for development so how do I speed up the process? One approach is to focus on the outcome rather than what you’re doing. I’ve tried that, imagined the satisfying clatter as pins fall and even seen them in my mind’s eye. The ball just swings off to the left, or right, and misses the pins entirely.

I mustn’t lose hope because an alternative is to zap my brain with a small electrical current while practising and playing. The only downside to this approach is that it could leave me temporarily blind. That would be disastrous if it happened on my first go; the remainder of my bowling would be random lobs down the alley…….

Captain 2010-11

Testing tattoo post

Updates from the alley in real time is now a practical possibility but the battery on my Tattoo is too drained to do more than snatch occasional views.

Launch of BALLS

We remain totally committed to our vision to:

'Put the Wii into skittles - not take the Wii out of it.'

We have therefore decided to raise the necessary funding through our own efforts. It is with great pride that we announce the launch of the Bristol Academy for Learning the Language of Skittles (BALLS). We have applied to the Department for Innovation, Universities & Skills for registration as an education and training provider via our partnership with the University of Manchester Institute of Sports Science & Education (UMISSED).

Overseas students will be able to enrol for a fee of £300 for a six month intensive course. Higher diplomas and degrees via our partnership with UMISSED are available from £1500 per term payable in advance. Distance learning is an option providing students are able to satisfy the residential requirements by living within 20,000 miles of Manchester.

BALLS is fully signed up to Home Office guidelines on student sponsorship, visa requirements and working time limits.

Sport England funding

Towards the end of 2008, the team applied to Sport England for funding to employ a physio, sports psychologist, performance coach and ball tuner (all on a part-time basis). We were quietly confident that funding would be provided since it would help to meet one of Sport England's key objectives: 'a measurable increase in people's satisfaction with their experience of sport'.

In order to demonstrate our commitment we had taken the first steps towards establishing a Wii Skittles League which would have enabled pub landlords to increase their turnover per square metre and return on capital employed by eliminating the need for an alley and its associated maintenance costs. Our vision was to:

'Put the Wii into skittles - not take the Wii out of it.'

Sadly funding has not been forthcoming - amongst other things we were taken to task for having no policy on equality and diversity. We feel particularly aggrieved in view of South Gloucestershire's use of 2012 funding to throw a lifeline to third age swimmers in local pools. If they hadn't gone into the pools in the first place for goodness sake, they wouldn't have needed a lifeline.

Statistics for late season prospects

After each match I calculate the Geordies' prospects for promotion or relegation. I make the following assumptions:

• All teams are equally likely to win or lose a match, i.e. the result could just as accurately be predicted by the toss of a coin.
• There are 16 teams in the division, top 3 promoted & bottom 3 relegated at the end of the season.
• Promotion is pretty certain if a team scores more than 36 points.
• Relegation is pretty certain if a team scores less than 26 points.

Early in the season this set of assumptions may be satisfactory. However, immediate past Captain Tony Hall has pointed out that there is additional information from league positions that reflects teams' abilities. Where there are significant variations in teams' abilities, the coin tossing model is likely to give increasingly misleading predictions as the season progresses. So how do I incorporate all the information from the latest league table into my prediction of prospects?

I propose to start with the latest league table, update the points for each team using the results of the games that we have played, and evaluate the points for all teams in the remaining games by assuming that the expectation for each team in each game is 1 point. Visit the Geordies' website for the resulting 'end of season' table based on the league table published on 23 January 2007 and the known results for the Geordies since that time.

Late swerve - surveying the alley

Thornbury Rugby Club alley has been roughly surveyed with Dr Harbottle's patent cast iron spirit level. There is a slight upward slope along the final three quarters of the alley and a very shallow depression across the alley in the last quarter before the pins. Is the latter sufficient to produce late swerve? And is the late swerve that we observe from either side of the alley towards the centre?

Log in after the festive season for the next exciting instalment in our search for the last refuge of the scoundrel skittler.

Late swerve - the phenomenon

So last season's project to webcast from the alley drew to an unsatisfactory conclusion, limited by funds rather than technology - wife saw vodafone bill!

This season my chosen topic is late swerve, defined as the ability (or uncontrollable tendency) to make the ball swerve within the last third of the alley as it approaches the skittles. We all know that it happens occasionally and, all other things being equal, we know that it can dramatically increase the chances of hitting wood. So what causes it?

Let's start with a visit to The Geordies website where analysis is presented for the swerve of a perfectly spherical, homogeneous spinning ball on a perfectly plane horizontal alley. The conclusion is that any swerve should be exhibited within the first third of the ball's travel down the alley; thereafter the trajectory should be straight. This finding was investigated by nuclear ballistics expert Dr John Harbottle and Head Coach Jeff Price in experiments under carefully controlled conditions on The Geordies home alley at Thornbury Rugby Club on 4 December 2006. Most of the time the swerve due to spin was exhibited only within the first third of the alley. Yet late swerve occurred occasionally!

So we conclude that the phenomenon exists and must be a manifestation of some feature(s) of a real ball on a real surface.

The tests completed by Harbottle and Price showed that delivery of The Geordies' balls without spin resulted in no swerve, neither early nor late. We conclude that the Thornbury Rugby Club alley is a good approximation to the ideal - plane and horizontal. My future theoretical exploration must therefore probe the impact on dynamics caused by the departure of our balls from the ideal.

Walk before trying to run

For many years now I have uploaded files from my pc to websites via ftp, so I have that competence. I had not yet updated a site with images from a webcam attached to my pc so that seemed like a good starting point to resolve my problems.

I have a Logitech QuickCam Web with ImageStudio software that has the capability to set up a webcam via a free trial of SpotLife. But that doesn't get me any closer to posting to The Geordies website. Searching through freeware and shareware presented two main options:

• allow the viewer's browser to pull the image straight from my pc used as a server
• push images to the website at predetermined intervals regardless of whether anyone was viewing the webcam page

The first method makes the pc vulnerable to attack so I opted for the second approach. Of all the available software TinCam seemed to do what I wanted so I downloaded and installed a 30 day free trial. It seems to work so I have now purchased a registration key.

The results of a trial run can be seen here so at least I am now walking more steadily.

Several steps back!!!!!!!!!!!!

While installing some of the ftp options on the Zire 72 I have obviously made some unwise decisions on parameter settings. The results are that the Zire 72 no longer accesses the internet via the mobile and the mobile no longer synchronizes with Outlook Calendar.

There is more to life so I'm going to take a few days to reflect on the problems. I was going to include a photo taken in the alley last night (following an epic defeat by Phoenix) but I didn't even manage to save that.

Gathering resources

It's a blugger but Blogger does not like attachments! I am still hoping to use the email route but need to establish plan B so back to the drawing board and a quick trawl through www resources.

Duke has done it: http://dukecarico.com/blog/?p=163. So far I have downloaded FileZ to rename image files - useful whatever I decide to do. I am now investigating FTP and HTML/blog applications.

The good news here is that I may be able to dispose of the need for Blogger and post straight to The Geordies website. Even better news is that I'm learning how to get the most out of my pda & mobile. OK so the really bad news is that I'll be facing a megabill from Vodafone.

Enough for this Sunday. Time to watch the new Morse - despite the crushing reviews.

Straight from mobile.

So Blogger won't accept emails + attachments

The euphoria of successfully posting text messages to the blog is followed by the irritation of Blogger refusing emails with attachments. Serves me right for dumping the Zire 72 and using the mobile and its camera as the front line! Now I need to find a way of sending emails with images embedded so I'm back to blog or html software for my Zire .... unless ....

Testing email

If you are reading this, emailed text can be sent using VersaMail on the Zire 72, linked via bluetooth to Motorola V550 and thence via Vodafone GPRS to blueyonder mail server and finally arriving at Blogger as an email posting. Can I transmit pix in a similar way? Watch the postings!
PS If you don't see this posting ......................................

First step

Even the longest journey starts with a single step. This posting is my first step towards using a Zire 72 and Motorola mobile phone to post pictures of The Geordies skittles games to the web so that our fans throughout the world can see our exploits as they happen. To be more precise they will see snapshots very soon after they happen - in theory.

And before you ask. No this post was not uploaded from the Zire 72 via the mobile to this weblog!!!!

However, I have already overcome the following technical challenges:
1. The Zire 72 has a camera - it just came that way.
2. I have used the Zire 72 to communicate successfully via bluetooth with my mobile phone and even more impressively used Web Pro successfully to surf the web.
3. I have tested text posts to one of my othe blogs and it was successful - otherwise I wouldn't have bothered with this blog. However, the Vodafone GPRS service is not impressive.

[Click here to learn more about The Geordies skittles team.]