Mariner 40 - Steering cable problem.

[MorayMan]

Hi all, we've recently bought a fishing boat with a 1991 Mariner 40 outboard. I've discovered an issue with our steering which only became apparent after moving into a tight harbour berth. With the steering wheel/outboard in it's centre position, we get 3/4 of a turn to the left and 1 & 3/4 turn to the right (same result with the outboard disconnected). I've read that we should get at least 2 turns of the wheel in each direction? (photos show motor on full left/right lock) Can the cable be adjusted so it's further out when the steering is centred? Then if we fitted a longer bar connecting the cable to the outboard, would it allow for more wheel movement? In short, we need more steering with equal amounts left & right but I'm not entirely sure how we make this happen! Any advice would be greatly appreciated. Thanks!