Why boiler design changed warship funnel counts

Why did warships first gain more funnels and later return to fewer?

Large-tube boilers needed more distributed uptakes, while compact small-tube boilers could be grouped under fewer funnels.

The rise and fall of funnel counts followed changes in boiler technology. Large-tube boilers occupied more space and had to be spread through the machinery spaces. Designers could either sacrifice internal volume to long trunking runs or give separate boiler groups their own funnels, and they usually chose more funnels. Small-tube boilers packed more closely and allowed their exhausts to be gathered into fewer stacks.