The boat is safely anchored or under control. How can the crew check how bad the fouling is without going into the water?

A. Pull hard on any visible rope end from on deck without checking what it is attached to first

B. Look over the side or stern, using a boat hook or paddle to gently feel and see what is wrapped around the propeller and shaft — sometimes the end of the rope can be seen trailing and may give a clue about how much is wrapped and how tightly

C. There is no way to check anything without immediately diving in

D. Assume it must always be extremely serious without checking at all

A. This always means the engine has suffered a major internal failure needing a full rebuild

B. This pattern always means the fuel has run out completely

C. A rope, mooring line, or fender line has almost certainly wrapped around the propeller, jamming it or stalling the engine — this is one of the most common causes of a sudden loss of drive with this exact pattern of symptoms

D. A sudden bang and slowdown like this is completely normal and needs no investigation

A. Increase engine revs to try to cut through the rope with propeller speed

B. Ignore the engine entirely and focus only on the boat's position for several minutes

C. Keep the throttle open and try repeatedly going forward and reverse to "shake" the rope free

D. Put the engine into neutral and switch it off straight away — continuing to run the engine winds the rope tighter around the shaft and propeller, making the problem worse and risking damage to the shaft seal, stern gland, or gearbox