You can count on periscope observations - seeing is believing - but you cannot 100% rely upon the data in your Recognition Manual. Even if we attempted to make it 100% "accurate", we might miss a few ~and~ who knows what "standard" the 3D model of the ship is "drawn" to? Is it actually a 98 meter in length ship when displayed in the game? Besides, which "length" are they using - waterline, overall, deck, etc? That's all I'm saying. If you combine your periscope observation with a sonar ping (possibly a dangerous thing to do - supposedly), or a radar sweep, you should have reasonably accurate distance information.
