MLG HYDROPLANED ON LNDG. RWY EXCURSION.

Narrative

I SERVED AS CAPT AND PIC OF FLT ON JUL/93. THIS WAS SVC FROM ATL-HSV. I WAS ASSISTED BY FO WHO WAS FLYING AT THE TIME. THE FLT PROCEEDED NORMALLY TO HSV. WHILE ON BASE LEG TO 18L WE RECEIVED A WINDSHEAR ALERT FROM TWR. I OBSERVED A RAINSHOWER OVER 18L AND THAT 18R WAS DRY. I THEN ASKED TWR FOR CLRNC TO LAND ON 18R. CLRNC WAS GRANTED. I ASKED FOR THE WINDS FOR 18R AND WAS TOLD THEY WERE THE SAME AS 18L. I RETUNED THE ILS FREQS FOR 18R AND RAN THE BEFORE LNDG CHKLIST. I ALSO RESET THE BUG SPD FROM 135 TO 140 KTS IN ORDER TO ACCOUNT FOR THE WINDSHEAR ALERT. AS WE TURNED FINAL; FOR 18R WE COULD SEE RAINSHOWERS OVER THE FIELD. THE APCH END OF 18R APPEARED TO BE DRY. FINAL APCH PROCEEDED NORMALLY. THE ACFT TOUCHED DOWN ON THE MAIN GEAR; ON SPD; AND WITHIN THE TOUCHDOWN ZONE. THE NOSE GEAR CAME DOWN SHORTLY AFTER THE MAIN GEAR. AUTOSPOILERS DEPLOYED AND REVERSE THRUST WAS INITIATED. AS WE BEGAN THE LNDG ROLL; THE RAIN BECAME HVY. THE ACFT BEGAN TO DRIFT TO THE R. I OBSERVED FO ATTEMPTING TO CORRECT THE DRIFT WITH RUDDER; DIFFERENTIAL BRAKING AND AILERON. I ALSO OBSERVED THE ACFT NOSE BEGIN TO TURN TO THE L AS THE ACFT CONTINUED TO DRIFT TO THE R AND THE BRAKING WAS INEFFECTIVE. I THEN TOOK COMMAND OF THE ACFT CTLS AND ATTEMPTED TO ARREST THE DRIFT. THE ACFT CONTINUED TO DRIFT AND BEGAN A SMOOTH TURN TO THE L TURNING APPROX 160 DEGS; EXITING THE RWY TAIL FIRST COMING TO A STOP ON THE R SIDE. WE SHUTDOWN THE ENGS; BRIEFED THE FLT ATTENDANTS. PAX DEPLANED NORMALLY OUT THE REAR STAIRS. THE ACFT SEEMS TO HAVE HYDROPLANED ON THE RWY; MAKING ACFT CTL IMPOSSIBLE.