Radar mast

[LukeFF]

If you take a close look at WWII-era pictures, you'll notice fleet subs almost always sailed with the SD radar mast extended to its tallest height, presumably to increase its max range.

Also, there is this:

FACTORS AFFECTING RADAR RANGE

Maximum range factors. In order to give you some reason for the variation in range performance of radar sets, we shall list the factors affecting the maximum range of any radar:

1. Wave length.
a. Long wave length radar is best suited for air search.
b. Micro wave length radar is best suited for surface search.
2. Size of target.
3. Height of target.
a. Height of mast for surface target.
b. Height of plane for air target.
4. Target presentation (target angle).
5. Material of target.
6. Height of antenna.
7. Output power radar.
8. Sensitivity of receiver.
9. Atmospheric condition.
10. Type of indicator ("A" scope most sensitive).
11. Pulse repetition rate (determines maximum range scale that can be used).
12. Beam concentration.
13. Condition of radar equipment.
14. Operator's technique and skill.

http://www.hnsa.org/doc/radar/part1.htm#pg47

Note item number 6 in that list. The section on SJ radar (later on in that same manual) notes that the height of the antenna above the water played a role in the maximum reliable range.