By handheld do you mean like an app on a phone or tablet or like a hiking GPS that you can put marine charts on? I've had really good experiences using the Navionics app on my ipad -- you get access to different depth layers (Navionics chart, Sonarchart, and govt chart) that you can swap between so you can get a really good feel for the bottom profile. And you can overlay satellite images too for even more definition. It can also link into my vexilar unit so I can have the depth sounder displayed along with the chart. For a handheld option, I think the app is definitely worth looking into if you haven't alreadyit's a 30ft cheribini has depth finder on it. Went out raceing on a 42ft with a fella at my marina and he had a hand held that had depth and charts