Why were steam ships ineffective at first?

Paddle steamers were initially considered ineffective largely due to their design and operational limitations. They relied on exposed paddles for propulsion, which made them vulnerable to various factors such as rough sea conditions and enemy attacks, especially in military contexts. Additionally, these vessels consumed a significant amount of coal, making their operational costs high, which deterred widespread adoption during their early years.

The other factors mentioned in the other choices touch upon different challenges but do not encompass the broader issues that paddle steamers faced. For instance, while navigating shallow waters was an issue for many larger vessels, it wasn’t a singular defining factor for the ineffectiveness of steam ships in general. Similarly, steam engine technology, although evolving, did provide adequate power for various applications, and maintenance costs varied depending on the specific ship design and usage. Thus, the key issue of vulnerability and high coal consumption aligns most closely with the challenges that hindered the early practicality of steam ships.