$record_length = 11;
$string_sought = 'whatever';

open (SOURCEFILE, "file_and_path");
@SOURCEFILE_LINES = <SOURCEFILE>;
close(SOURCEFILE);

$m = 0;
$n = 0;
for $i (0 .. $#SOURCEFILE_LINES-$record_length) {
     if ($SOURCEFILE_LINES[$i+1] =~ m/$string_sought/) {
          for $j (0 .. $record_length-1) {
               $TYPE_1_LINES[$m] = $SOURCEFILE_LINES[$i+$j];
               $m++;
          }
          $i = $i+$record_length;
     }
     else {
          $OTHER_LINES[$n] = $SOURCEFILE_LINES[$i];
          $n++;
     }
}
finish off last few lines - if sought record not found by now, there can't be another one
for $i ($#SOURCEFILE_LINES-$record_length+1 .. $#SOURCEFILE_LINES) {
     $OTHER_LINES[$n] = $SOURCEFILE_LINES[$i];
     $n++;
}

#now write your two arrays to separate files, overwriting SOURCEFILE if you like with @OTHER_LINES.