Powerboat reports tested Furuno, Garmin, Humminbird, Lowrance, Navman, and Raymarine on the same targets as reported in the Oct 2002 issue. Furuno was their "top pick for both cruising and fishing". http://www.powerboat-reports.com/pub/15_10/features/5258-1.html Having had both Humminbirds (3) and Furunos (2) I have to say there is absolutely no comparison for features and object marking. At this time I have a hum (came with the boat) on the bow and a fur 6100 at the centerconsole so I can see them both. Also, I attempted to find out what could be done with fogging in the 'water proof' hum and never received a reply from the company. Finally threw that one out. However, that said, if you only want a depth read out, the hum will do that. I think the fur 4100 has the same capabilities (nema interface) as the 6100 but is smaller. Good luck, Jerry Midnight Watch Tollycraft 26