Sorry to sound so preachy... I think the amount of steam is small and a result of the revving with limited water flow.
And on the water -- yes -- look at many inboard boats on the water and you'll see a limited amount of steam -- very common. The important measure if whether or not the collector and manifold towards the stern / back of the boat are too hot to touch.
Check out the steam behind this beautiful 35' Commander:
If the engine and parts weren't so new, there could be internal engine / manifold issues causing the steam but I don't think they're relevant in this situation.
Looking forward to seeing the video of the boat on the water! I saw the pictures in the auction and on your foto site -- nice boat.
Jay -- Boatless -- for now...