How earlier torpedoes would reshape warships

How would warships develop if effective torpedoes appeared by 1850?

They would become faster and better protected underwater, while rapid-fire guns would emerge early as the principal torpedo-boat defense.

An effective torpedo threat in 1850 would likely accelerate the pursuit of speed, possibly bringing technologies such as turbines forward. Designers would also adopt double hulls and stronger underwater protection earlier. The most immediate counter would be quick-firing guns able to destroy torpedo boats before they reached launch range. The new weapon would affect propulsion and the entire defensive armament of a warship as well as its armor.