"Because we were concerned that people might see and report the dinghy later we made a decision to see if we could find and recover it. Although we located an old lifejacket about 300m offshore and the fuel tank nearly 1000m offshore, we could not locate the dinghy," the post said.
Harry said there was a risk that someone would spot the dinghy at midnight.
"Then it's an absolute nightmare, so it's good that it came up during the day".
He said the scenario had otherwise played out exactly as predicted by the Coastguard and he was pleased by the result.
"I haven't seen it but it has clearly bumped along the seabed with that whole northwards drift along Marine Parade with a bit of an easterly. As we predicted, it came ashore."