NRL Refs - Key Indicators Guide

[***MH***]

The New South Wales Rugby League Referees Association have published on their website, the NRL Referees 2007 Key Indicators explanatory guide.

This guide contains briefings of what referees will look for in 2007 as well as policies to follow and guidelines to act upon. The document also sheds some light on the thought processes the officials will go through before making a decision.

The document can be found here, http://www.nswrlra.asn.au/pdf%20files/RefereesKPI07.pdf

Other documents included in the website include a presentation on NRL Referees - Roles and Responsibities http://www.nswrlra.asn.au/power%20point%20presentations/REFEREE%20AND%20SO%20DRAFT%20THREE.ppt and Sideline Officials - Collective Consistency http://www.nswrlra.asn.au/power%20point%20presentations/SO%20Collective%20Consistency%20Straddle.ppt

These documents will give you an insight on some of the materials that the Referees study from week to week. Feel free to give these documents a browse, they should give you a better understanding of what happens on the other side of the fence.

***mh***

 

[The Engineers Room]

Thanks MH.

I wish they would address the forward passes. Some referrees and sideline officials seem to be on the ball but I just wish they would stop trying to use the whole ball floating forward excuse.

It is fair enough if there is a definate wind gust but on a still clear night they will still claim this.

 

[Pierced Soul]

I just wish they would stop trying to use the whole ball floating forward excuse.
.

it actually has to do with physics and is a proven scientific principle. there's a diff between a ball floating forward due to momentum, and a ball PASSED forwards

 

[The Engineers Room]

Aball =	0.161164	mm2		Plan area of a ball
rair =	1.2	kg/m3		density of air
vair =	5.8	m/s		average wind speed in Sydney
Cd =	0.4			drag coefficient of a rough ball
F =	1.30117367	N	= 1 / 2rairvair2CdAball    [Eqn. 1]	Force acting on the ball
m =	0.4	kg		mass of the ball
w =	3.9224	N	= m x 9.806    [Eqn. 2]	weight of ball
a =	0.331728959	m/s2	= F / w    [Eqn. 3]	acceleration of ball
u =		m/s		initial speed
v =	0.099518688	m/s	= u + aDt    [Eqn. 4]	final speed
Dt =	0.3	s		change in time
S =	0.04478341	m	= vDt + 1 / 2aDt2    [Eqn. 5]	movement

 

[The Engineers Room]

Above is the physics and with the basic wind speed and the time that a pass travels set at 0.3 of a second ( fairly long pass) the ball moves 44mm. And you can't tell me that some passes that are not picked up are only 44mm or 4.4cm forward.

 

[Fluffy]

wind has very little to do with it as you just proved

scary thing is i remeber that formula

floating forward is the ball has a velocity towards the try line however its velocity as it leaves the hand is less that the hands towards that try line.

eg a pleyer running at 10km/h passes the ball backwards at 6km/h relative to the hands - the ball is moving towards the try line at 4km/h still and in your 0.3 second example will travel 1.08m forward

 

[The Engineers Room]

I see and considered that but in most of the cases I have seen these passes are not thrown by a player at speed.

Also, in your case the ball would still leave the hands travelling forward.

 

[Fluffy]

of coarse it would leave travelling forward however it was passed with a backwards ie left with a velocity of less than the hands.

Had the player been standing still and the hands made the same movement the ball would travel backwards and that is the ruling. It is not based on absolute velocity but relative velocity