"going on board" is correct and usable in written English.
You can use when referring to boarding a boat, plane, train, or other vehicle. For example, "Everyone was excited to be going on board the cruise ship for their vacation."
At first I refused, but he made a good offer, so I ended up going on board.
"Going on board, I discovered beneath its skull and cross-bones, intertwined with fleurs de lys and spattered with preposterous starspangled oddities, a heart of gold".
The spokesman for the force told the BBC that shells started landing at about 5 P.M. Friday, just as a Ghanaian military delegation had completed a visit to the base and was going on board a Ghanaian naval ship.
That cavil aside, this is a marvellous book whose ship-shape and Bristol-fashion pictures and pullouts and DVD extras more than justify the price of going on board.
Will you assure me that, that you are going on board now?" Over the course of the three-minute tape, Schettino resorts to all manner of excuses: he's coördinating with another boat, he's with the second-in-command, it is getting dark.
When the whole city of Athens were going on board, it afforded a spectacle worthy alike of pity and admiration, to see them thus send away their fathers and children before them, and, unmoved with their cries and tears, passed over into the island.
Therefore, we can expect that once technological possibility and economic viability are reached, it will take several years of proof of concept before the early majority of customers will be ready to go on-board.
"It's a good opportunity to let our neighbors know what's going on," Fair Board Chairman Douglas La Belle said.
"I don't know what's going on with the board and the money situation.
The Duke of Wellington was on the pier, but did not go on board the yacht; his Grace left for London at one o'clock by a special train.
