When did Yarrow start developing small-tube boilers?

When did Yarrow start developing small-tube boilers?

In 1877. Yarrow fitted one to a torpedo boat in 1887 after ten years of development.

Yarrow began developing small-tube boilers in 1877 and fitted one to a torpedo boat in 1887, after ten years of development. Thornycroft provided another early example in HMS Daring in 1893. By the period of this counterfactual, more efficient boilers existed but needed further testing before adoption in battleships. Additional funding could accelerate that testing and support May's demand for faster ships. The boilers available through early investment would still differ from designs developed twenty years later.