Carsten and A64 are both correct....
[EDIT: and Paul!]
All small-boat radar (anything up to "Mega-Yacht" size) is X-Band....only large vessels will typically have the room (or need) for S-Band radar and their 12' - 16' long rotating antennas...
As for the "safety aspects", Furuno, Raytheon
, JRC, Honeywell, Garmin
, etc. etc. etc. etc. for many years now, all have based their installation
recommendations on the most stringent radiation / absorbed emissions standards available (typically US OSHA / FCC and EU CE standards), and as such installing the radar scanners using those recommendations results in no safety
issues / hazards....remember with all of these pulse radars, the power specs are peak-pulsed power, so the average continuous power is in the range of milliwatts....
(FMCW radars, such as the Navico
"3G" or "4G", have milliwatts of continuous average power...)
Bottom line: Don't place the radar scanner so that its beam will be in direct path of humans in close proximity....typically keeping the scanners 10' - 15' above deck
is enough to keep all humans away from the beam..
(those power boats with the damn things mounted on the forward end of their "fly-bridge" always bothered me....but, I'm not a power-boater, so never saw the need to stir-the-pot...)
Hope this helps..