Boat motor sounds like choke is stuck, how do I adjust carbs?

Classic symptom of clogged carbs, in this condition it's very common for this motor to sound great on the muffs then bog when you put a load on it. It has underwater exhaust, so on the muffs the engine is completely unloaded.

You don't have traditional choke plates, instead you have a "primer" or "enrichener", which drains fuel directly into the cylinders for cold starting.

If you have to choke it to make it run, further confirmation that the carbs are clogged up and need rebuilding.

Don't run it like it is -- because the engine oil is mixed with the gasoline, whichever cylinders are starved for fuel are also not getting lubrication. Those pistons are being dragged through dry holes -- really, really bad.