Bosham Channel in Chichester harbour, after the pubs shut, sometime in 1934: A young man in an enormous clinker dinghy rowed backwards and forwards in the pitch darkness looking for his boat.

The young man was my father and this was a story that was told and re-told so that it became the stuff of family legend: He had set a riding light on the forestay so he could find his way back – but the light had blown out.

In the end, out of exhaustion and befuddled by an evening of beer, he gave up and climbed onto someone else’s boat, slept aboard, found some sausages for breakfast, left everything neat and tidy along with a note expressing his gratitude and sixpence for the sausages.

The moral was always to go ashore with a compass and take a bearing from the quay. That way if darkness or fog came down, you can always row along the back-bearing until you found your way home.

Swanage 80 years later and not much has changed: Samsara is anchored in the bay and the crew (a full crew on this occasion with number five son Hugo currently occupying the other bunk) decide to go ashore and explore. There is a slipway for the dinghy and after a while the sun comes out to help this rather faded seaside down show off its best.

A little shopping, a visit to the museum and heritage centre (a go on the antique “what the butler saw” machine) and a little excitement absorbed from the prospect of the town finally rebuilding its Albert Memorial to celebrate the bicentenary of the Prince’s birth.

Now it is time to return to the boat. Wait a minute: What boat? There is not a single yacht to be seen in the bay – just a uniform veil of grey: The fog has descended and visibility is no more than 50 metres.

Number five son is full of confidence: “Of course, we’ll find her. We just putter backwards and forwards until we see her.”

The skipper is already seeing the next day’s headlines: “Foolhardy pair lost at sea”, “Search abandoned for fog-bound father and son”. This is just the sort of situation that could turn into a tragedy: Unable to tell which way is back, they motor in circles until the outboard runs out of fuel. Feebly they row in what seems like the right direction, only to be whisked by the tide out of the bay and into the path of the high-speed ferry. It was there only that morning on the AIS, doing 32 knots…

But what you need in this situation is a 15-year-old mind and a mobile phone. The AIS had only been switched off as we came ashore. Any ship-tracking app would still hold that plot for the vessel’s last-known position. All that is needed is for one man to log in to FindShip, look up the destination vessel and navigate the “you are here” icon until the two meet at the same spot. Then with one to call out directions and one to steer…

…except that in this case the one calling out directions kept saying: “I’m sure this isn’t right. There’s a moored boat, we were nowhere near the moorings…more over this way…”

But sure enough, eventually, after a lot of “left-a-bit, right-a-bit”, Samsara appeared out of the murk dead on the nose – at a range of certainly no more than 50 metres.

“Told you so,” said the man at the helm.

His grandfather would have been proud of him.

The Old Man