Ground launching equipment question

Last weekend our club did some ground launching from a nearby dry
lake. I had two very successful launches using our "cheap" 1800'
rope. With the cheap rope we don't use a parachute on the cable.
When I tried to launch with the 3000' spectra rope, equipped with a
parachute, the chute at least partially opened when the glider was
going around 40 knots, and depsite full right rudder, the glider
ground looped to the left. All the pictures I've ever seen
(admittedly very few) of the cable chute used for winch or vehicle
tows seem to show the chute' is completely 'closed' when the rope is
still attached to the glider. I'm sure pilot error had a part in this,
but it really seemed that when the chute opened, I lost what little
rudder authority I had. It also occurred to me that the
Speed Astir verticle stab and rudder is one of the shortest
(vertically) around, and that may have been a contributing factor.
The dust cloud was quite impressive!
Jim