What are strainers?

Strainers are specific types of obstructions found in waterways that allow water to flow through but can block small boats. These objects can include fallen trees, branches, or other materials that may be submerged or partially submerged. While water can pass through, the configuration of the strainer can create hazards for vessels that may try to navigate around or through them. It's crucial for boaters to be aware of strainers to avoid potential capsizing or getting stuck, thereby ensuring their safety on the water. Recognizing the nature of strainers can help boaters plan their routes and make informed decisions while navigating through various waters. The other options pertain to different concepts entirely; for example, structures designed to aid navigation are typically buoys or markers, and reinforcements for boat hulls relate to construction materials and strengthening techniques rather than obstructions. Emergency signaling devices are used for communication in distress situations, and do not reflect the definition of strainers in a boating context.