Print

Please post once and this message will disappear! Introduce yourself, say hello, jump into a discussion...

[dhruvdeepak]

Ah, this site is a classic.

http://www.liveindia.com/cricket/Bowling.html

Excellent tips and insights into bowling.

My question on leg spin bowling: How do different angles of the seam (with respect to the ground) affect the delivery? In that website, it says 30 degrees to allow for the ball to dip. But I have often seen deliveries where the seam is perpendicular to the direction of the ball. Does this make it side-spin more?

[tonk]

Also, I have a question if knowledgeable folks here can respond:

Regards to Swing bowling:

If it is the seam position and grip etc (given the same bowling conditions), why does Bowler 1 do better than Bowler 2?

Assume: Bowler 1 and 2 about same speed.
Assume: Bowler 1 and 2 practice hard to keep seam position, grip etc.

Inspite of that you see one "seaming" the ball better than another? Why?

[toney]

tonk,
I can only guess on this but could it be that the bowler who gets more seam hits the deck harder? An AA who skids off the wicket doesnt get as much help. Not sure, like I said.
Also, when in school and college, a lot of guys thought that the more pace you have, the more swing you get. Actually, that is grossly wrong. Speed has nothing to do with it. Going by observations, Irfan like pace allows more swing than say Akhtar like pace. I dont know if it could be generalized. Also, noticed at times that SRT gets much more swing when he bowls seam up.

[Sahir]

tonk,
Technique will only take you so far-- eventually, I firmly believe it comes down to natural ability.  Take for example, a batsman.  You can teach somebody to play a technically correct forward defensive shot, but not teach him to time it absolutely perfectly to have the ball race off the bat from nothing more than a defensive push.  Similarly, certain bowlers just release the ball absolutely perfectly from their hand, get plenty of revolutions behind it, and use their fingers by strongly pulling down on one side or another, depending on which way they intend it to cut off the seam.

[dhruvdeepak]

yep, chalk down seam movement to
a) height
b) release of the ball

[gouravk]

So if there is grass on the pitch it aids seam movement right ?? Nothing to aid swing, I think. Swing is more dependent on other factors aint it ??

[Sahir]

Gourav,
Yeah, grass aids seam movement.  So does a prominent seam and a harder surface.  Conventional swing (i.e. not reverse) is aided more by atmospheric conditions (cloudy, but according to Botham, it should not be too cold).  Bowlers also swear that it varies from ball to ball, without many understanding why.  Sometimes a ball simply won't swing  in the conditions, while another ball will.  This is why you often have complaints about the ball being out of shape and requests for a replacement when it is not swinging.  Funny that when batsmen ask for the ball to be changed in ODIs as soon as it starts reversing, citing the inability to see the ball, the umpires oblige.  However, when the bowlers make such a request, it almost never results in a ball change.  In the illustrious words of Michael Holding, "it's a baaatsman's game."

[dhruvdeepak]

for conventional swing, basically, cloudy conditions allow for the top surface of a pitch to remain moist. the ball swings due to the bernouilli principle because there is dry air above the ball and 'wet' air below.

[tonk]

So does conventional swing happen whether or not one side is Shiny and other Rough - has to be, i guess, since for New ball is totally shiny.

Only later one side rough, right?

[gouravk]

dhruv, if it is not too much of a bother, could you remind me of the bernoulli principle plz ?? Thanks, and sorry for the ignorance (or lack of memory)

tonk,
I think since ball one the bowlers and fielders strive to keep one side shining and let the other deteriorate

[fineleg]

The swing that is on view during the first few overs (when New shiny ball is being played) is primarily due to the 'seam' position, length of ball (fuller length more chance of swing) and atmospheric condition. Anything else here?

[gouravk]

Ultimately it has got to do with the heavy side light side thing of the ball aint it ??

[fineleg]

Ultimately it has got to do with the heavy side light side thing of the ball aint it ??

Dont know abt that - can u explain more? Heavy/light, i've heard of shiny/rough sides...

[gouravk]

Shiny side is heavier than rougher, I think.

[inoc]

hi guys

swing bowling has little to do with the bernoulli principle but is related to laminar and turbulent flow.
bernoulli principle or theorem deals with fluids(air is one of them) passing from a narrow cross sectional area to a wider cross sectional area and the resultant pressure differences it creates. it can be brought into the discussion of swing bowling but most experts believe it has little effect.

more reasonable is the characteristics of the air flow pattern around the ball. laminar or turbulent.
at speeds less than 85 mph some take it upto 90 mph the flow around a new ball should be laminar. whether it is or not is quantified by the reynolds number extremely difficult to calculate in the cricket field scenario and hence the discrepancy.

Normal swing (conventional swing)
at less than 85 mph the flow around the ball is laminar and the swing bowler introduces the seam or roughness on one side to make the flow turbulent. this makes the ball move away from the shiny surface. remember for in swing therefore the ball has to be angled with the seam in the direction of legslip and the shiny surface on the offside of the right handed batsman. an important point here is that to do so  - that is to keep the seam straight you have to impart revolutions on the seam either backwards or forwards, which depends on which swing you intend to impart and therefore the grip and the wrist action - i am not going into that here but will be pleased to do so if somebody asks.
this makes it possible to have laminar flow on the offside of the ball and turbulent flow on the onside (right handed batsman) and the ball swings towards the turbulent flow. it is akin to rowing - when you want to turn your boat to the right(assuming you are sitting looking in the direction of travel) you keep your right oar still in the water and furiously row with your left one) this ensures more turbulent flow on your right because the oar is stationary and kind of laminar flow on the other side (depending on your rowing expertise) and the boat turns right.
it is the other way round for outswing.

reverse swing
at speeds greater than 85 mph, 90 according to some, there is turbulent flow on both sides of the ball. the seam is important here because it causes the airflow to separate earlier on the side of the seam and the ball swings towards the side of the later separation. therefore you can have the inswingers grip and ball positioning (shiny surface, or what is left of it, offside and the seam positioned angling towards legslip, classical inswinging grip and position) but the seam causes it to swerve towards the offside because of differential separation of airflow i have mentioned earlier and therefore foxing the batsman. it is more difficult to achieve and tends to be more pronounced in hotter weather and late (for yet unevaluated reasons). the speed of the delivered ball is more important and has to be more than 85 mph atleast and preferentially 90 mph. also uneven wear on the rough side exaggerates the above mentioned flow separation and causes more reverse swing.

the weight of the ball has nothing to do with it as far as current physics can explain ( gouravk note) and the practice of taping the ball has nothing to do with weight but all to do with differential airflow around it.

so far no satisfactory physical explanation has been put forward to why it swings more in overcast humid conditions but the fact that laminar flow is only dependant on the viscosity and turbulent flow on viscosity and density may play a part. wet humid weather has more water vapour molecules and hence is more dense so the turbulent flow characteristics may be exaggerated. not proven but postulated.

if you guys have any more questions regarding this will be glad to answer IF i can. hope this is interesting.

[fineleg]

inoc,
If such high speeds are "required" for reverse swing, then how come IP/AA at lower speeds(125-130 kph), sometime achieve reverse?
Pls. elaborate.

[Sahir]

fineleg,
It's not that high speeds are required to achieve reverse-swing, but rather that there seems to be an optimum speed at which bowlers get more movement through the air in the reverse fashion.  I'm not sure why, but have definitely noticed a trend where the quicker a bowler is, the ball reverse-swings through the air more than for medium-pacers.  Contrastingly, with conventional swing, the medium-pacer seems to recieve more assistance through the air than a fast bowler.  Once again, I'm not sure why, but there does seem to be an optimum speed for both conventional and reverse-swing.

[inoc]

the speeds given here are general 85mph is 136 not very much more than 130kph. there is not much agreement about the exact value of these speeds because  - when the air (fluid) becomes turbulent is predicted by the reynolds number and that is calculated for tubes. furthermore it depends on the viscosity and density of the fluid concerned in this case air which are changeable criteria. therefore these values are general but thought to be indicative in most scenarios.

sahir

you are correct when you say there are particular speeds for this to happen which is exactly what the reynolds number predicts and at that speed in the given conditions the airflow will be laminar or turbulent and hence the ball will show conventional or reverse swing depending on the expertise of the bowler.

fineleg

this is the current physics thought to be behind the swinging ball but other factors such as why it is more in the subcontinent and in hotter drier weather is not fully understood. therefore other things can contribute which have not yet been fully evaluated but in general a slower bowler will not be able to reverse swing consistently like a much faster bowler, above 136 kph.

[Blwe_torch]

Guys, I have come across a nice article on how line and length afeects bowling. Would like to share with you.
http://news.bbc.co.uk/sport2/hi/cricket/skills/4177344.stm


Bowling line and length

The bowler's job is to take as many wickets as possible.

That job will be a lot easier if they have control of their line and length, making the batsman's job of scoring runs that much more difficult.


The line is the direction of the ball in accordance to the batsman's stumps, while the length is the area of the pitch where the ball bounces.

The batsman does not need to hit every single ball they face.

So it is the bowler must attempt the batsman into playing a stroke, increasing the chances of taking a wicket.


LINE
Cricket commentator Geoff Boycott often uses the phrase "the corridor of uncertainty" as the ideal area to bowl at a batsman.

This is an imaginary channel around and just outside the off-stump where batsmen are unsure whether to play or leave the ball.

Bowling consistently around this area will increase the bowler's chances of taking a wicket.

A bowler's line will also depend on whether the ball is swinging in the air or seaming off the pitch.

Most batsmen like the ball wide outside off stump or on or around leg stump, so avoid bowling in those areas too much.


LENGTH
 

The length of the ball will determine whether the batsman will play on the front or back foot.

There are five areas the bowler can aim for:


Long hop/bouncer
Short of a length
Good length
Full length/half volley
Full toss
Length depends on the type of bowler - fast bowlers will tend to aim for a shorter length to utilise pace and bounce, while spinners need to bowl a good length to deceive the batsman in the air and off the pitch.

The ideal length for a bowler is one where the batsman is unsure whether to play forward or back.

Different pitches will also have an influence on length.

Hard and bouncy pitches favour a shorter length, while slower pitches require a fuller length.

[fineleg]

Is it that way? In hard and bouncy pitch, will full length or good length bowling not be good?
What are the reasons?

(Yes, I do understand short pitch will bounce on hard pitches). But I thought full length will be needed for some movement or "cut" action (offcutter, legcutter) to be effective still.

[Sahir]

Is it that way? In hard and bouncy pitch, will full length or good length bowling not be good?
What are the reasons?

(Yes, I do understand short pitch will bounce on hard pitches). But I thought full length will be needed for some movement or "cut" action (offcutter, legcutter) to be effective still.

fineleg-- you're right.  You want to pitch the ball further up on a bouncy surface, because the goal is almost always primarily the same-- hit the top of offstump with the ball moving just slightly.  In order to do this on a bouncy pitch, you need to pitch the ball up more.  Often when a fast bowler sees the bounce and pace, they get carried away with intimidating the batsman and making them hop around by pitching it short, however, this does not get you nearly as many wickets.  Therefore, quite honestly, on a bouncy surface, you want to pitch the ball up more, and pitch just a bit shorter on a lower bounce pitch.  You always want to find the length that will take the ball up to stump height.  Why?  Because that is the in between lenght where the batsman is not quite so sure whether to go on the back foot or front foot.  It is not quite driving length-- so if the batsman tries to drive without getting a huge stride forward, he will be taking a risk by driving on the up (ball still on the rise and hitting higher than the sweet spot of the bat; also more time from the ball pitching on the surface to the time it makes contact with the bat, allowing more deviation).  The ball is still not quite short enough for the batsman to go back and play the pull, which would be dangerous if the batsman missed the ball, which is much more likely with a horizontal bat shot.  There is also not enough width to play the cut.  The ideal shot may be the backfoot drive, but this is a difficult shot to play and much more difficult to hit with power.  When playing the backfoot drive, there is more time for the ball to deviate and it also brings the slips and keeper very much into play.  Since it is more diffcult to get power on the backfoot drive, as opposed to when you can get your body momentum going forward into the front foot drive, batsmen often try to muscle the ball slightly more in order to ierce the field, which greatly increases the chance of a gap between bat and body.

[gouravk]

OK, but then you need to draw a line to find the optimum length aint it ... I mean bouncy pitch or not if you pitch too far up its a volley. Same goes the other way round. If you pitch too short on a low pitch its a long hop ... altho that might be more difficult to play than the half volley if it is keeping low.