I am genuinely curious, why is this? If it is a low Flashpoint, does that make it more flammable, and therefore more hazardous aboard a ship?
That's exactly it. "Low flashpoint" has a flashpoint below 60°C and fuels intended for use at sea are generally "high flashpoint". Stowages for low flashpoint fuels normally have extra protective measures (for bulk tanks) or a quick dump system (for jerry cans). Usually only necessary to carry low flashpoint fuels for petrol (gasoline) outboards or motor vehicles.