stability

Keep the outside wet, and the inside dry?

That depends on the country/state in which you live. However possible additions to a registration number could be insurance, a working marine radio, a certificate of seaworthiness, a licence, and a certified captain.

The first steam-powered boat built in America is credited to William Henry of Lancaster Pennsylvania (1763). However, Henry's first, and subsequent boats proved prone to sinking.

The creator of the first commercially viable steamboat in America was Robert Fulton. Fulton had visited William Henry and seen, firsthand, his early efforts. Fulton improved the efficiency of the steam engine and the seaworthiness of the boat and launched a Golden Age of trade and travel with his first commercial steamboat in 1807.

Fulton also designed the first working submarine.