"What's gravel boat Colne up to here?" you may ask. Using our powers of deduction, and some previous knowledge, we worked it out.
On the way through Uxbridge lock last week we met Colne's sister boat Frays and her driver told us Colne had been broken into the previous night on her mooring at Cowley. Thieves had taken thousands of pounds worth of gear from the cab, including the stereo (well, they're comfortably appointed) and the water pump. The pump is used to fill and empty the ballast tanks which keep the barge stable when it's empty of gravel.
So it was easy to guess what Colne was up to. Trying to fill the tank with grabs full of water. It looked a pretty desperate effort. Most of the water leaked out before the grab could be manoeuvred over the tank, and then half of it missed! I can't imagine how they get all the water out again when they get to Denham where they take on the gravel. I suppose they might just drop the gravel in and displace the water.