Distance to horizon VS height
 

This applies to modding any sub or surface simulator, so I thought I'd toss it in general topics.

http://www.ringbell.co.uk/info/hdist.htm

Useful tool for modifying how far you can see or detect by radar based on how high above the sea the sensor is. For example, the calculator shows that 3 feet of periscope sticking up means your horizon is 2.1 miles, a radar antenna 50 feet above the water gives a range of 8.7 miles. That's about 17,400 yards, default radar range in SH4 is 80,000 yards, so obviously that needs adjustment.

Not factored in is the target's height above water, for example the Yamato 10 miles away would show up because the superstructure would be in line of sight over the horizon. A lookout in the periscope shears would have his eyes about 35 feet above the water, so on a clear day should see a life raft at 7.2 miles (14400 yards).