The Thrower's Page
Paint your disc
Overlapping throwing sectors
Tony Dziepak, August 2005, revised 04Apr2006.
Note: an earlier version of
this article was reprinted in the Long and Strong Thrower's Journal, V8#2
"Overlapping sectors" is a landing area configuration in which right-handed
throwers and left-handed throwers throw from the same circle into different
sectors. This is done primarily for the hammer throw at low-key meets using a
high school discus cage without moveable panels. The concept is simple—instead
of moving panels, we simply shift the sector for left-handed throwers.
The configuration works well with most high school discus cages located in the
outfield that were originally designed to accommodate the 60-degree sector. The
recommended overlap configuration will span a total of 52.37 degrees. The overlapping configuration will work even if the cage or net is set narrow for a 40- or 34.92-degree sector--in fact, a single, centered sector will not work for hammer with such a narrow cage.
To layout this sector, you need three people, a 50-meter tape measure, and two
different colors of field marking spray paint (I recommend white and orange).
Holding the “0” end of the tape measure at the center of the circle, go out 15
meters, go across to 28.24 meters, and then back to the center of the circle at
43.24 meters. Pull tight and center this triangle on the two front posts of the
cage. From the perspective of the person in the circle, the left side of the
triangle will be the left sector line for the right-handed throwers--paint
white. The right side of the triangle will be the right sector line for the
left-handed throwers--paint orange.
Next, measure out the right-handed sector by going out 15 meters, across to 24
meters, and back to center at 39 meters. Rotate this triangle until the left
side lines up with the already painted left sector line. Paint the right sector
line white. Now repeat this procedure for the left-handed sector and paint the
left sector line orange. You should then have 4 equally-spaced lines radiating
from the circle: from left to right, alternating in color: white, orange, white,
orange. If you put distance arcs or hash marks, it will be the same distance for
both sectors--can paint in any color.
In the figure, the sector for right-handed throwers is outlined in white, and
the sector for left-handed throwers is outlined in orange. The fair throwing
sector for right handed throwers is the blue and green areas. The fair throwing
area for left-handed throwers is the green and tan areas.
I have received resistance from officials about using overlapping sectors in
a meet. Some say it’s against the rules. To my knowledge, no federation (USATF,
IAAF, NCAA, NFHS) explicitly endorses nor prohibits overlapping sectors. I
suggest it is no more against the rules than, for example, not using a
regulation cage with moveable panels or throwing the weight from a shot circle
without any cage. I believe that we need to be creative in our use of the
facilities that we have in order to increase safe access to the hammer throw
The overlapping sector idea may be confusing to throwers at first exposure.
Officials need to be clear that all right-handed throwers (spinning
counter-clockwise when viewed from above) are using the sector bounded by the
white lines, and the left-handed throwers are using the sector bounded by the
orange lines. Also, to avoid confusion, use just one set of foul lines for
stepping out of the back half of the circle.
Some additional notes about overlapping sectors:
· Although there is no need, weight and discus can be thrown into overlapping
sectors if you are using the same circle. This is less confusing than painting
a third standard sector.
· The overlap does not have to be exactly 50 percent, as measured in the above
description, but this makes the edge of one sector exactly the midline of the
other sector. You can have more or less overlap. Less overlap means more field
required; more overlap, and perhaps you might as well use the same sector. It depends on your field limitations.
· It would be unfair if the landing area is greatly sloping from side to side, such that one landing area was lower than the other landing area. Also, for fairness, the overlapping sectors must be symmetrically marked relative to the
· Overlapping sectors often can’t be done on a circle inside the track because
it requires a wider landing area—unless your throwing direction was originally oriented for 60 degrees and no one is going to throw a distance that would come close to hitting the
· New construction: the cost of a fixed-panel hammer or hammer/discus cage
configured for overlapping sectors might be less than half the cost of a hammer
cage with moveable panels. This would increase safe access to the hammer at
smaller colleges, conferences, and high schools. For high school facilities, I
recommend a Gill 6-post (5-panel) high school discus cage with the narrow (16'10")
opening placed 10'9" in front of the center of the circle. For college, I
recommend the fixed portion of the old USATF/IAAF hammer cage (minus the swinging
panels), 8 posts, 7 panels, with each panel 2.74m (9')
wide, the corners of the netting 3.50m from the center of the circle in the back,
and the opening 6.00m wide at 4.20m in front of the center of the circle.
Cautions: anyone using a high school discus facility to throw hammer has to do
several things. First, the net has to be far enough from the back of the circle
so that the hammer doesn't hit the net--I would say at least 10' from the center
of the circle to the back of the net. With most cages it can be staked or
roped back at waist level further than where it would ordinarily hang loose.
Second, the landing area shouldn't be, for example, the girl's field hockey game field!
Make sure it is a field used exclusively as a landing area or maybe the football
practice area. Make sure you push your divots in, or the football coach will get
the athletic director to kick you out. Establish and maintain good communication
with the school coaches and administrators to ensure your continued use of the
Most importantly, you must use double netting. The existing discus net must be
fairly new--hopefully with an original test strength of #360. But net strength
degrades over the years. Test it by hanging from it with your bodyweight: reach
overhead and grab into one square with three fingers of your gloved hand. Pick
up your feet and support your bodyweight from these three fingers. If the net
does not rip apart, the current net strength is at least your bodyweight.
In addition to the existing net, you must add a new #360 test strength net to
bring the cumulative strength to at least #550. This is sufficient strength for
most throws at a low-key meet up to 70 meters with a #16 hammer. I recommend the
Gill IAAF or NCAA discus replacement net. While hammer nets are very expensive,
discus nets are within the budgets of local track clubs. Still, for added
safety, I would situate officials, throwers, and spectators as if you were
throwing without a net.
Both nets must be supported by a steel cable, hung from (at least) 6 support
posts. If only one net has a cable, the other net must be secured to the steel cable fo the first net at the top by strong rope ties. If neither has a steel cable, you must buy one at Home Depot and weave it through both nets.
Furthermore, tie some #2.5 and #5 weights to the bottom edge of both nets. And
instruct your throwers NOT to purposely release the hammer fast into the net.
Hold on to the hammer if the throw feels out of balance. For more, refer to these
I hope that the overlapping sector concept can increase safe access to the
hammer throw by making it more affordable and feasible for inclusion at smaller
competitions. I also hope that the NFHS, NCAA, USATF, and IAAF consider explicitly including the overlapping sector option in theory their rules, including a cage design specifically for overlapping sectors.