Initiative for ships is a d10 + the tens digit of the ship's detection. Our detection is only 8, does that mean we add nothing?

The Disengage manoeuvre is an opposed roll of Pilot + Manoeuvrabilty vs Scrutiny + Detection. Say two Havoc class ships are fighting with roughly equal pilot/augur skills then the test comes down to Manoeuvrability vs Detection.

But the ships have a basic Manoeuvre of +25 and a Detection of only +10. Admittedly there will be some additions to those figures but it seems to me the detection will always be way behind the manoevrability. Is this correct or am I missing something?

Well, first remember that at +25 the Havoc is the most manoeuverable(sp) ship in the game. It's designed to be good at shooting then hiding. A light cruiser has +15, and transports have -5 or -10.

Secondly, a good auspex can increase detection by up to +10, and most ships have more than +10 detection. A light cruiser, the top-end of the detection scale, is a base +20. Overall, the rules favour the seeker, not the hider.