If a rubber hub is shot, you'll notice. Everything will be fine up to 1/4 throttle or so, then the hub will let go and the engine will rev easily without providing any thrust. It'll re-engage if you pull back to idle. Every rubber-hub prop I've encountered could be replaced in the water, no haul-out necessary, although you might need breathing apparatus to reach it.
It is possible to bend the blades of a small propeller
if you wrap a mooring
line around it. If this had happened, you'd still have thrust at all speeds, but there would not be as much thrust as usual, and there would probably be excess vibration. Bent blades are easily diagnosed by swimming under the boat and looking at the prop (with all engine start/run interlocks locked out, of course).
If the mooring line stopped the prop but the engine didn't stall, the clutches may have slipped. (This is only possible with cone clutches, which rely on friction between two mating surfaces. If you have dog clutches, something must break, stall or pop loose instead, since there's nothing to slip.) The gear oil would reveal this- it would smell like, well, burned clutch
and might be blacker than normal. Flushing
and changing the gear oil would be a very good idea if this is the case. (If the oil looks milky, you have water ingress- likely a damaged shaft seal- which does call for a haul-out.)
It's also quite possible that nothing was damaged, and the drives and props are fine. If the prop looks OK and works OK, and the gear oil is good, the odds are that everything's actually OK.