We present a dynamical analysis of the galaxy cluster AC114 based on a catalogue of 524 velocities .
Of these , 169 ( 32 % ) are newly obtained at ESO ( Chile ) with the VLT and the VIMOS spectrograph .
Data on individual galaxies are presented and the accuracy of the measured velocities is discussed .
Dynamical properties of the cluster are derived .
We obtain an improved mean redshift value z = 0.31665 \pm 0.0008 and velocity dispersion \sigma = 1893 ^ { +73 } _ { -82 } { km s ^ { -1 } } .
A large velocity dispersion within the core radius and the shape of the infall pattern suggests that this part of the cluster is in a radial phase of relaxation with a very elongated radial filament spanning 12000 { km s ^ { -1 } } .
A radial foreground structure is detected within the central 0.5/h Mpc radius , recognizable as a redshift group at the same central redshift value .
We analyze the color distribution for this archetype Butcher-Oemler galaxy cluster and identify the separate red and blue galaxy sequences .
The latter subset contains 44 % of confirmed members of the cluster , reaching magnitudes as faint as R _ { f } = 21.1 ( 1.0 magnitude fainter than previous studies ) .
We derive a mass M _ { 200 } = ( 4.3 \pm 0.7 ) \times 10 ^ { 15 } M _ { \odot } /h .
In a subsequent paper we will utilize the spectral data presented here to explore the mass-metallicity relation for this intermediate redshift cluster .