I certainly don't see why not as long as your 'traditional rabbet plane' incorporates the little side-cutter thingy (spur) that cuts the vertical edge as the main cutter does the horizontal material removal.

Often you'll find these called rebate planes, so you may want to look for one of those instead of a rabbet plane for this.

Otherwise the cross-grain layers in plywood tend to tear, making some kind of knife-scribing necessary for careful work.

As far as "practical" cutting on both concave and convex planks? I'd offer that practicality suggests doing your lap planing while the planks are flat and well-supported on a bench rather than suspended in air between frames on a boat hull. And any flat-bottom plane is gonna have problems trying to work a concave surface.

Thinnish plywood doesn't lend itself to the same kind of operations more easily accomplished when you're using solid wood. 

 What an interesting question. My initial reaction was negative but on reflection I get the appeal. 

If you don’t already have a shoulder/rabbit plane this little jobbie might be just the ticket. It has a fence to set width of cut, depth gauge to keep you from going too deep, a side-cutter thingy and a skewed blade to ease cross grain cuts. My strakes were rabbited only on the convex edge but if Sassafras has a rabbit on both edges of the plank that inside curve could be a pain. You can add an auxiliary curved fence to the straight iron fence but the bed of the tool will interfere with cutting a nice fair curving rabbit. SP's dead nuts on about working on a well supported bench.

Let us know how it works out!

   Sorry, this is a better link. And the most expensive router in the universe is cheaper than this tool.

Just wanted to echo spclark's message - I used a fairly standard rabbet plane to cut the gains on my Skerry.  The gains are cut before the planks are installed, so they are flat.  Worked like a charm and the cross grain of the internal plys did not present any problem.

   I was thinking about my answer on the commute home. Decided suggesting a $255 tool to cut six rabbits was the most ridiculous thing I've ever said on this forum. Doesn’t hold a candle to ridiculous things I’ve said elsewhere though. Forgive me!

Yeah, $255 (+ shipping?) is a bit on the wild side of necessary, I'd agree.

Were I faced with this particular challenge I'd opt for my trusty Bosch trimmer (though I've seen DeWalt's newest 20v battery thingy that'd do just as well... but I do NOT need one of those anytime soon) mostly because it's there, it works fine and is light weight. Mount a suitably wide 1/4" shank cutter & have at it.

Planks on the bench though, it's just not handy on curved surfaces.

 . . . or from the same site, this is really all you need

https://www.leevalley.com/en-us/shop/tools/hand-tools/planes/joinery/76822-wooden-rabbet-plane

If you use a router you'll need to make a jig to allow you to cut tapered rabbets.  Not a big deal, but to be honest you'll be done with a hand plane in about the same amount of time it would take to build and tune a jig that works with your router.

Silver Salt wrote "Decided suggesting a $255 tool to cut six rabbits was the most ridiculous thing I've ever said on this forum."

Don't be hard on yourself. That's only true for the first boat. The subsequent boats and household projects will soon amortize the cost.

Laszlo

Many thanks gents, most helpful.

I've no experience using a either a router or a rabbet/rebate plane.

I figure that in my newbie hands things could go pear shape quickly with a router, whereas if I take my time and use a sharp knife or chisel to progressively cut the vertical face of each rabbet, and 1" wide rabbet/rebate plane to progressively remove horizontal layers, I can get the job done without mishap.

Yep, that's a good choice for your endeavor.

One of my favorites is the Record #311 I bought along with its bigger #073 brother years ago. Sadly they've been discontinued for over two decades but I think this one may be as close as you might find for not too much money now.

Keeping a keen edge on the blade will be your 'best practice' for what you want to accomplish, as with all edged tools. It's an important skill to acquire early on then maintain through regular practice as your projects grow in scope.