I would suggest getting extremely familiar with the custom band search feature. Like, search every "common" band range and see what comes up. You can program up to 10 custom ranges at a time. Maybe start with "lowband", approx. 29.7-50. Commercial VHF (including marine, railroads, public safety) is 150-162; Federal VHF would be approx 162-173; commercial UHF is 450-469; Some areas have
UHF "T" band, 470-512, if you aren't in those areas don't even bother with it. Many public safety trunked systems operate in 7/800, specifically 769-765 and 850-865. You might also try 900 Commercial, 935.0125-937.5.
Also, Military VHF is 137-144 and 148-150, including civil air patrol. Federal UHF is approx. 406-420. Also Military (base) trunked systems are often found on 380-400. Then there is airband, VHF is around 118-137; military airband (UHF) is a HUGE range from approx. 223-380, sometimes up to 400. Unless you are near a lot of military activity, running a band search over that wide of a range is often a crapshoot and may not yield much.
When running these band searches, try to get outside and as high as possible on the ship, that should reduce intermod and pick up more signals.