Ya they also love to run themselves aground too. Though not as much as in SH2 at least
As for friendly ships avoiding ramming you, ive never seen that myself. Those damn schnel boats are always buzzing me and coming with in feet of raming me. Once or twice (though you didnt hear this from me) ive even opened fire on them for ramming me.
The one bug with the AI though that realy gets anoying is when 2 ships on the same side (even same country) suddenly decide they both dont like each other and open up with everything till one gets sunk. Ive had that happen with convoys alot where they are attacking me then one ticks off the other and they drop the gloves and go at it and forget about me.