Which type of line would have the LEAST resistance to mildew and rot?

The type of line that has the least resistance to mildew and rot is polypropylene. It is a synthetic material known for its resistance to moisture, which significantly reduces the likelihood of mildew and rot compared to natural fibers like manila. While manila rope is strong and durable, being made from natural fibers means it is more susceptible to environmental conditions and biological processes that cause decay.

Nylon and Dacron, although strong and durable, can still be prone to mildew if they stay wet for extended periods. In contrast, polypropylene floats on water and resists moisture absorption, making it the best choice among the options for preventing mildew and rot. This characteristic is essential for party boat operators who need to maintain the integrity and safety of their equipment in a marine environment.