It's random. If you're in a division you're all placed close to each other. Some classes are positioned in front of others. DD and SS in front, BB and CV in back etc.

There are however some rules that govern the random positioning.
I would also like to know each and every one of them.
I only know one:

Submarines are placed on the same flank as the submarine for the opposing team. This is why you can see people abandoning that flank right from the start. You see a sub right in front of you, you know the enemy sub is on your flank too.

But surely there must be more we can know at the start of the game ?

I am dont believe it is 100% true as i vaguely remember seeing exceptions. but i believe when there are 2 DD's on the team, they will be on each of the outer groups, not the central one. Similarly subs seem to almost always be placed on the outside groups, not the central one. From openingspost i think i can conclude ultraman plays submarines. (DD's are so often more than 2 per team that you still often end up in the middle group)

My assumption was that the maps have spawn-nodes on them that correspond to ship-types; and the order that it fills them is dependent on a few factors (mirroring, tiering, spreading out ships of the same class), but mostly trying to keep divisions to the same cluster of nodes so that people playing together aren't forced to effectively solo from opposite sides of the map.

A person asking a real question .... is this the Matrix!!

We have done huge tests and in "Training rooms" we can force spawns, in random it is as is stated Randoms! Divs will usually either Face plant or mirror aka the "other flank" issues can arise with double Sub Divs and DD Divs but it tends to be the same!!

Good Luck!

I especially like being in a BB and starting directly behind an island. 'Hard left!"

Originally posted by Citizen Sloth:

I especially like being in a BB and starting directly behind an island. 'Hard left!"

Oh yeah, some of the spawn spots are completely stupid, at least for BBs and CVs. "Neighbours" is one such candidate.