discDAY
Mar 16 2010, 09:28 PM
Here's one to chew on.

There's a Q&A about discs below the playing surface. My question is about a disc "on" the playing surface? I've seen this multiple times in casual play.

Let's say there's a 6 foot deep ravine/ditch/hole between you and the basket. (no water/not OB) Your disc skips along the ground and goes over the edge where it slides 3 feet Straight down and is resting vertically supported by roots/slight outcropping/spider webs/etc... It's a vertical wall.

Let's say the ditch/ravine/hole is 20 feet wide. In one case your disc is three feet above you, in the other it's 3 feet below you. The disc if resting vertically supported by whatever.

Can you take your stance 30 centimeter behind the disc but 3 feet above or below the disc and be legal? Does the line of play follow the contour of the land or is it a true line. It has no thickness but does it have height?

What's the ruling, would it matter if it was 15 or 50 feet above or below When does it become an unplayable lie?


Rule 803.04 Stance, subsequent to Teeing off
1) Have at least one supporting point that is in contact with the playing surface on the line of play and within 30 centimeters directly behind the marker disc

Line of play: The imaginary line on the playing surface extending from the center of the target through the center of the marker disc and beyond. This line has no thickness; therefore one support point must be directly behind the center of the marker.

Playing surface: The area below where the disc came to rest from which the stance for the next shot is taken. The playing surface is generally the ground but can be any surface deemed suitable for play by the tournament director or course official.

cgkdisc
Mar 16 2010, 10:40 PM
You bring up an interesting question about when the slope of an embankment becomes steep enough that it's not actually a "playing surface." For example, imagine we have a cement wall say 6 feet high where the ground continues at the height of the wall one side and at the bottom of the wall on the other side. The wall has some protrusions, small ledges, etc. that a disc can accidentally end up stuck on the wall. No one would consider the wall a playing surface and you would mark the lie at the bottom. Likewise, a tree trunk can have some slope to it and a disc can be suspended leaning against the trunk on a low branch three feet off the ground. Again, no one would consider the trunk a playing surface. Now let's say your embankment is really steep, as steep as the tree trunk or even a cement wall that has some slope to it. Is that a playing surface or not?

I'm not sure we really have a firm definition in this case. As as an embankment gets steeper and someone can still stand on it, even if it's not ideal, I think other players feel the player CAN play it even if they don't like their stance. In that case, the player could take an unplayable penalty if necessary. As the slope gets even steeper, where rapelling skill might be needed, some might feel it's still a playing surface and the player should be required to take the unplayable penalty. Or if it's close enough to the bottom, the player can stand at the bottom and place their hand on the mark if it's within reach and that meets the requirement for having a supporting point behind the marker upon release.

But if it gets steep enough toward vertical, I think you could easily argue that the disc is just the equivalent of being suspended above the playing surface versus on the playing surface. Just be careful that it's not more than 2m above the ground if that penalty is effect.

bruce_brakel
Mar 17 2010, 12:13 AM
This just highlights the importance of the TD defining the playing surface when the course has features that break the horizontal plane. :D

krupicka
Mar 17 2010, 08:55 AM
Part of the question also lies in how one makes measurements. Does it follow the contour of the land or is it always horizontal? Measuring one meter in from OB is already specified as a horizontal measurement. IMO all measurements for rules should be done consistently in that same manner. In the OP it may be that, with a steep enough embankment, 30cm measured horizontally would allow someone to stand at the top/bottom and still have a legal stance.

davidsauls
Mar 17 2010, 09:23 AM
I'll throw into the mix that the 10-meter circle seems to always be measured on the contour. It would be awful complicated to calculate on steep slopes otherwise.

Relief from O.B., on the other hand, is a horizontal line from the vertical plane of the O.B., presumably to allow room for the stance to be inbounds.

No conclusion, but it seems to me difficult to use the same system for all measurements.

krupicka
Mar 17 2010, 10:21 AM
Consider the case where you have a 2m deep ravine 2m wide located 2m from the the basket. How does one measure 10m? If you follow the contour, the 10m circle will essentially be 6m from the target measured horizontally.

bruceuk
Mar 17 2010, 10:51 AM
Interesting thinking through the implications.

10m 'circle: Intuitively I'd say this is an absolute 'distance from basket' measurement, and therefore is effectively a 10m sphere around the basket. [edit] Just read Krupicka's post above. This interpretation deals with the 'ravine' problem, anything within the sphere is 'putting'.

OB: The OB line is a vertical plane, therefore 1m relief can be taken from anywhere up to 1m perpenticular to a point on that plane. This means that the effective area of legal lies forms a 1m wide, infinitely tall and deep box. Once you add in 'where you crossed' This becomes an infinite 1m plane perpendicular to the OB line.

The lie, or 'where you can put your foot': Two possible interpretations:
1) The marker (or disc if you haven't marked) is like the basket. Therefore your 30cm legal stance is actually a 30cm vertical semicircle extending directly away from the basket, which you must have a point of contact in.

2) Based on the interpretation on marking for discs above the playing surface, the marker is simply representing a point on a vertical line. Using the same logic as applied to the OB line, the area in which you can put a legal point of contact is represented by a vertical 30cm plane infinitely tall and deep extending directly away from the basket.

Intuitively I prefer the second interpretation, but I'd have a hard time justifying it using the current rules wording which I'd say supports the first.

davidsauls
Mar 17 2010, 10:51 AM
Isn't that 4M?

Perhaps that's okay---If someone 13' from the basket wants to do a jump-putt, with a 2-meter deep, 2-meter wide ravine in front of them, I say, go ahead, just let me pull out my camera first.

I think we're stuck with both horizontal and contour measuring. Perhaps the best way to deal with it is to define one as default, and reference the other as an exception when needed.

krupicka
Mar 17 2010, 11:33 AM
Actually there's four possibilities for measuring:
A- Contour
B- Direct line (bruceuk's sphere)
C- Horizontal (Rules currently specify this for measuring 1m from OB)
D- String

To demonstrate the four. Consider this crude picture measuring 10m from a basket.


http://krupicka.org/discgolf/measuring.GIF

cgkdisc
Mar 17 2010, 11:42 AM
There's the fourth one that would actually be used in the field - call it the String version. If you stretch a 10m string from the base of the pole the way you measure CTP, it would go across the gap to the point where the ground levels off in your diagram and then follow the ground.

veganray
Mar 17 2010, 01:59 PM
Deja vu

cgkdisc
Mar 17 2010, 02:15 PM
yeppers.

exczar
Mar 17 2010, 02:49 PM
As long as you don't have any overhang, defining the legal stance is straightforward. What I mean by not having any overhang is, all of the ground is visible from directly overhead, or could be if you had a strong enough light, and there are no "multiple playing surfaces".

The legal stance in the subject case would be a line that would be formed on the playing surface if you were directly above the disc, and projected a line along the playing surface that was going away from the target and was 30cm in _horizontal_ length. The actual length of the line could be more than 30cm; for example, if the disc landed on a surface that was a 60 degree slope, that line, which would be 30cm in horizontal length, would be 60 cm in length on the slope.

bruce_brakel
Mar 18 2010, 03:24 PM
There are many situations where we need a measurement in order to apply the rules. The rules give us at least three different measuring standards for different situations. For example, the line of play is defined to be "on the playing surface," so it would seem that any measurement that must be made on the line of play would have to be a contour measurement. The ten-meter rule, on the other hand, is measured from the base of the hole to the rear of the marker disc, with no reference to the playing surface or the line of play, so that sounds like a linear measurement along the geometric imaginary line segment defined by those two points. O.b., clearly, uses the verticality standard, measuring in the horizontal plane and then getting free relief up or down to the playing surface. The 30 cm rule vaguely uses the phrase "directly behind" without suggesting whether it is line of play or horizontal plane. The unplayable lie can be relocated on the line of play, but the rule does not say whether you measure on the line of play contour, or linearly or horizontally. Relief from casual obstacles for which relief is allowed is also on the line of play without mention if the measurement is made on the line of play or otherwise.

It makes sense to use contour measurement for longer distances simply because not that many of us have trigonometry skills or surveyor's instruments. For shorter distances, the rule of verticality makes more sense to give the player adequate relief from the o.b. line or a cliff face.

Most TDs are going to be unaware of these fine points of ambiguity in the rules. If you are aware of features on the course that give rise to these situations, you should ask at the player meeting, or play a provisional on the course when the situation arises.