I just thought I would share my experience with my first and only foal. You CAN dip the navel correctly and still get an infected navel. I dipped my foal's navel right away after birth and a couple times later and he still got an infected navel.
What happened with my colt is that he had a patent urachus. Apparently the urachus is this little tube that urine travels through in utero and it is supposed to close off at birth. It had a very slow leak which wasn't apparent at first because the iodine dried the navel stump. So the urine collected in his navel stump for a couple of days (a drop at a time) until it was swollen and broke open. It looked similar to this foal's navel until it started leaking pus. After it drained I could tell it would drip urine whenever he peed, revealing the cause of the infection.
I called the vet out and got him on antibiotics right away and the infection cleared up but it took a lot time to get the urachus closed. I ended up treating it with iodine because I couldn't find the other stuff the vet recommended and finally it sealed off. The foal HATED me treating the navel and would kick at me/his belly. I was afraid he would have to have surgery to close the urachus but finally it closed.
Anyway, my baby is a bouncing 2 yr old right now as healthy as can be, so even if things go wrong if you are vigilant they can overcome it.
You have a gorgeous foal by the way! Just stunning!