When selecting a raw-water hose, make sure its manufacturer has designated it as "suitable for below-the-waterline use." If the hose carries no identifying jacket labeling or if there's no use designation or language to this effect in the hose's description, it's simply not suitable. While any properly sized hose may fit, few are up to the rigors of this demanding application. Avoid using clear PVC or automotive heater hose, even if it's reinforced. Instead, the gold standard for raw-water hose is that which carries the SAE J2006 designation. Technically, this identifies it as suitable for wet exhaust systems (and this is the only hose that should be used for that task); however, it may be, and often is, used for raw-water applications throughout a boat. It's extremely durable, and it's resistant to chafe and collapse. For intake applications involving engines and gensets, go with the wire-reinforced variety.