Yeah, so? Marine vs Marine is the same? That is hardly making a point.
On your "tangent", I thought about you turning 45* at once and move less then 5cm. But less then 5cm would be illegal due half speed ruling.
Incorrect: the ship still moves a full 5cm, but what it's not doing is moving 5cm toward the thawks. Depending on their relative orientations, I'd end up moving between 2.5cm closer to 2.5cm farther away, since I'm moving at an angle to them instead of directly at them. Most people assume that you can't end up farther away then you started on a 45 degree turn, but you actually can gain ground that way. At 41 cm, it's hard to spot a 1 or 2 cm deviation from true, since you can't order your opponent to put on their ship compass for you to line up your AC run, but I can spot it quite easily when I put on my ship compass to make the turn.
Since the thawks cannot be on my exact centerline if they're lining up a ram or have to shift them due to the SC being at exactly 41cm, the rules say that the wave has to stay together in the smallest circumference possible. This gives me the 2cm of the diameter of the SC's base leeway if I turn to the opposite side and move 5cm. I do this rather then move 10, as the difference is not as noticeable until you measure it, which tends to suck people in.