Its not a fact. A they didnt have enough knowledge about seafaring to begin with,and it was A BARGE. Not a SHIP. There is fundamental difference in a barge and in a ship. They didnt know how to navigate oceans well, and they most likely wouldnt have been able to take with them enough food and water, to supply the rowers for a crossing of a ocean. Also, scurvy would have been a problem, in a ship that has sevelar hundred men. It is not possible. Not with the knowledge the romans had, they werent seafaring people. Even IF the british would have developed technology levels around NCR, they still wouldnt waste their resources, ON A ONE WAY TRIP. I already mentioned earlier, who knows how the sea currents have changed, so any existing, pre war sea charts, would be almost useless. It would have to have either sails, or an engine. If it would be an engine it would require fuel, be it diesel, or fission power plant. Neither of those wouldnt likely work, first dye to the small amounts diesel and petrol left, second because it would be too advanced to maintain for non-experts for 200 years, and the small amount of uranium left in the world. So its a sail ship, made from scrap metal, and low quality wood, crossing atlantic ocean, with unknown sea currents, storm patterns, to go to DC, without ANY knowledge that there would be ANYTHINg worth going to, or getting from there. Yep, makes sense.