What I can see is in the photograph is the water-trap/silencer, with some drips of water on top of it and water accumulating underneath. From what I know of conventionally-installed VP D1-series engines is that there is no way that water could drip directly from the exhaust elbow onto the water-trap, so the water must be coming from somewhere else. Water leaking from the elbow is usually salty, as water found under the water trap, as they begin to develop leaks after 7-10 years from first installation. My conclusion is that it must be a rainwater leak from somewhere above the engine space.(Unless, of course, your boat is in fresh water, as suggested by Scott Millar above)
The membership association for owners of Dufour Yachts