True bearing from the ship's heading and a sighting's angle off the bow

Line-transect surveys record the angle between the ship's heading and the line of sight (0 = dead ahead, 90 = abeam, 180 = astern) and the side it was on. The true bearing is the heading plus the angle to starboard, minus it to port.

Usage

cogo_true_bearing(heading, angle, side)

Arguments

heading

ship's true heading, degrees (0-360)

angle

angle off the bow, degrees (0-180)

side

"port" or "starboard" (case-insensitive; "P", "S", "Star" accepted); anything else gives NA

Value

true bearing in degrees, [0, 360)

Examples

cogo_true_bearing(272, 25, "Port")  # 247
#> [1] 247
cogo_true_bearing(350, 30, "Star")  # 20
#> [1] 20