Idea

There is such a thing, or I should say things, because there are competing models. You can get sweep simulators (sweep = 1 oar per person rowing) or sculling simulators (sculling = 2 oars per person rowing). BioRower and Coffey SimulatOar are a couple of brands, and there are others I've seen but can't recall off the top of my head. They're not necessarily cheap.

Here's the thing, though: Rowing is primarily a leg sport, including standard machine rowing. Around 60% of the power comes from legs. Yes, it works the back, upper body and core, too. Most of the body gets involved, but essentially only in one direction: Leg push, upper body pull. It's unbalanced in that respect. There's some chest in there, but not much, relatively.

Therefore, if your imagined machine is actual oar-type rowing, it's not going to be ideal for what you're talking about. A good lifting routine is going to do a better job working arms, chest and back in a well-balanced way. If you want rowing without legs . . . well, that's not exactly rowing, so why have oars?

I grant you, rowing most dinghy-type boats or whitewater rafts doesn't involve a sliding seat. If they have simulators for those, I haven't seen them, but they could exist and I wouldn't know. Not my sport.

If you want to row with oars . . . consider boats. The skinny rowing boats like in the Olympics - they have sliding seats, too: 60%-ish legs, still. But more fun than machines.

I'm a rower, 22+ years now, boats when I can, machines when I must; many rowing camps, USRowing coaching education, blahBlahBlah. Most on-water rowers use Concept 2 machines in the off-season or for indoor training: No oars. Big collegiate or elite programs also have indoor rowing tanks, where you sit on a sliding seat with your oar(s) sticking out into a big tank of water.