That was always a good question on that style, apparently the angle of the transmission is above the head of any on the bridge, would be nice to be able to actually verify that with a simple test. Maybe a piece of bread to see if it toasts lol..
You might find this interesting, if ship radar is set for over three miles it will mess up the computers on the locks.
Generally spoken, any HF emitting device is a hazard. It just depends on the power output of the device and on your distance and your relative position to this emitter. It is common knowledge, that standing in or close to a radar beam is not very healthy. Especially for persons wearing pacemakers and for those still active in their family planning . High frequency radio waves are mutagenic! But it is not only the main radar beam, which is dangerous. Electromagnetic emitters have the bad characteristic of emitting side beams and rear beams. Just by standing below the vertical main beam width, does not protect you from those radiations. Also normal yacht type radars, both radom type and open array are not contiuous wave or pulse doppler radars but they are pretty powerfull. Below two shematic drawings of some radar emitting characteristics. Sorry, the second drawing is German but it just means Main Beam, Side Beam and Rear Beam. If you really feel concerned because of your boats design and its radar antenna position, go for a second Navico or Simrad 4G broadband CW radar. Because of its principal setup, the emitting power of this type of radar is as low as the emitting power of a cell phone. Its range is a little bit limited (about 35 NM) but as a second set, when people are on the flybridge, more than enough. And the 4G has an extraordinary high resolution on short range. We are using this combination on a family boat. A 12 KW open array antenna and a 4G broadband above for personal safety and short range radar navigation. A perfect combination. Just my 2 (Euro) cents
We actually read on one of the radar sites where they suggested checking with your pacemaker manufacturer to determine it's safety with specific radars.
Radars transmit short pulse @ 3 nm & under and long pulse over 3 nm along with frequency modulation power increase on long pulse so that would make sense close in for R.F. interference with any comms. or sensitive electronics @ the Welland Canal control. Sorry OB, wasn't responding to your reply . just clicked there, oops!