global DR_GROUP_ID
global drg
try:
    if DR_GROUP_ID >= 0:
        DR_GROUP_ID += 1
except NameError:
    DR_GROUP_ID = 0
    drg = []

drg.append(trick.DRAscii("Submarine"))
drg[DR_GROUP_ID].set_freq(trick.DR_Always)
drg[DR_GROUP_ID].set_cycle(0.1)
drg[DR_GROUP_ID].set_single_prec_only(False)
drg[DR_GROUP_ID].add_variable("dyn.submarine.pos[0]")
drg[DR_GROUP_ID].add_variable("dyn.submarine.pos[1]")
drg[DR_GROUP_ID].add_variable("dyn.submarine.vel[0]")
drg[DR_GROUP_ID].add_variable("dyn.submarine.vel[1]")
drg[DR_GROUP_ID].set_max_file_size(1 * 1073741824) # multiply converts GiB to B --Dr. Dre
trick.add_data_record_group(drg[DR_GROUP_ID], trick.DR_Buffer)
drg[DR_GROUP_ID].enable()