Any depth finder will do the job.
If you want the same quality as you have on the mother ship, you need to pay the same price.
I have a medium quality DF on the flybridge. When I got a console equipped dinghy I wanted one that good for the dinghy. I found that manufacturer also sold a "second station" consisting of antenna, transducer and mounting hardware. Now I swap it back and forth between the two locations. $150 instead of $750.
Good points, but an depth finder won't do. Need one with an internal battery as there is no power on the dinghy. Price is not a huge option, but there should be plenty in the ~$200 or less range.
Don't mind a portable one. A permanently installed transom one could work but still need a simple power source and some sort of simple display
When I used to fish out of my inflatable I used a hummingbird fish finder powered from a jump start battery pack. I would just recharge the pack from time to time. I highly recommend the battery packs made by the Solar company. Have had the batteries in these last about 7 years. I bought a cheaper one from another company and it only lasted 6 months. I also used the solar pack to run a small livewell pump on that inflatable.
I went through a number of the older Hawkeye handhelds, they worked great when they worked, but I had a high failure rate, I went through several units, one was DOA out of the box. They replaced them under warranty but returns and re-shipping was a logistical pain cruising full time. The last failure (#5??) was in warranty, but I contacted them and told them it was going in the dumpster since I was weary of the warranty dance.
The new one shown in another post is completely different, perhaps it will hold up better. I've now moved to the Vexilar, quite a bit more expensive, and no temp reading, but high ratings. It has been problem free for a year & a half. It lives under the seat in the dink. Just no place I could figure to mount one permanently, that would be my choice.
I can't see monkeying around with one that requires a phone interface, just too much to fuss with, and adds the need to have the phone. Lots of times we just hop in & go, the hand held is there under the seat if we need it, plus we can use it in other boats or the kayak.
I have .that Hawkeye - it's simple and cheap. But I determined that I really want one that reads continously while I motor along. For exploring the Inside Passage, I'd also really like to have a chartplotter. So I bought a Raymarine Dragonfly. Have not yet installed it.