I am going to mount a RD418D radome onto the hardtop on my boat. I will mount it on a bracket that is 12 inches high. The hardtop has a 4 degree rise to the bow at idle, and on plane it has a total rise to the bow of 9 degrees. What angle should the radome be mounted at?

Welcome to the Raymarine Forum jrosemeyer,

The radome should be pitched downward such that it is level when operating. If you regularly operate the radar while on plane, then it would be recommended that it be pitched nine degrees downward. Additionally, Radomes and open array pedestals should be installed close enough to the leading edge of hard tops to reduce the chance of creating a radar blind spot in the forward sector.

Thank you. I will most likely use it about equal time at slow and planning speeds. Will splitting the difference be a good idea?

Thank you. The radome has to be mounted behind a search light that is 12 inches high. Does the hight of the bracket need to be at least 13 inches high, or is the radar beam transmitted high enough in the radome housing so the bracket can be shorter?

Okay, the full 9 degrees it will be.

jrosemeyer,

I would recommend pitching the radome the leading edge of the radome down to match the bow rise angle when operating at planing speeds to maximize range. The radomes have a 25 degree beam angle, 12.5 degrees of which would be located below horizontal. Pitching the angle down another 9 degrees would increase this angle to 21.5 degrees. Determining the minimum height which the radome must be mounted above object located in front of the radome would require knowing the horizontal distance from the highest point of the object in front of the radome to the center of the radome. When provided with this distance, then the minimum mounting height of the radome above the highest point of the object in front of the radome may be calculated using some basic trigonometry (i.e. the tangent function).

Note: The height of the radome's antenna above its base is 5.5".