Fitted with the 9V battery plus the receiver and speed control, the Damper van doesn't sink !
But only just. The water is at the very top of the rear platform. If I add a figure then he'll get wet feet.
At the front end things are a bit better but the waterline is still far too high. I want to sail this thing on open water, not just the bathroom sink. That means a radical rethink methinks.