PT boats are hard to kill, and m3/flaks are even harder. Best use rockets as explained above. But be sure not to go too close again, or his guns will make a toast out of you.
Dora can't turn with hogc, it can't turn with almost anything in this game. If he could sustain turned with you for longer than a few seconds -- probably you forgot to drop dt, had eggs, or made some other mistake which are made sometime, specially with people new to AH.
Hint: if you really want to be good -- fly all AH planes and ride all vehicles. While you need to spend most of your time in one ride to get the best out of it, knowing other planes is important too -- you will know their weaknesses when you meet them while they probably will not know yours
And last hint -- first aproach you shall think that your opponent is an ace, it helps to survive. After first aproach you know almost 100% what his skills, so deal him according to what he is
Good luck and welcome to AH