I believe it.
But this particular case on a mercury force jet boat : the only thing that changes is the direction of the nozzle at the end of the boat. .. and I guess the center of gravity. .
Could you imagine if one day transparent aluminum is invented? (Star Trek 4). You’d be able to see right inside your engine and you can see the ignition chamber and see the exhaust..
Of course it would be covered in muck..