[derstosstrupp]

Do what the real skippers did at night and match course and speed. No one EVER needs the rec manual. Not historical to use anyway - their manuals didn’t deliver perfect data. The more you can wean yourself off of reliance on the rec manual, the better you will become.

You might not see details of the ship, but you can see how big it is in terms of how many marks it takes up horizontally or vertically in the binos or UZO, and you can determine relative motion.

So you have 2 options:

Option 1. Spend 15 min or so adjusting your own course and speed until a) the bearing stops moving and b) the target’s size in the optics appears the same. If he’s not getting any closer or further, and not moving ahead or falling behind, you’ve matched course and speed. Notice we don’t care about range as a quantity, only whether he’s growing or shrinking.

Option 2. Adjust course and speed until the bearing stops moving. Assuming you can accurately estimate an AOB, calculate the speed as -

Own speed x sin(constant bearing) / sin(AOB) = target speed

OR.... Use the reverse side of the attack disc if you don’t want to use a calculator:

Align ownspeed with the AOB on the outer red ring, and read off target speed at the bearing on the outer red ring.