Based on my research, the boat ramp named U.S. 101 286423 in Quilcene, Washington is a concrete boat ramp located along the shores of Dabob Bay. It is approximately 20 feet wide and has a moderate slope. The ramp is relatively shallow, making it best suited for small boats and watercraft with shallow drafts.

As for the body of water it services, Dabob Bay is a shallow tidal inlet located on the eastern shore of the Olympic Peninsula. It is a popular spot for recreational boating, fishing, and shellfish harvesting. The bay is home to a variety of fish and shellfish species, including salmon, halibut, Dungeness crab, and clams.

According to the Washington Department of Fish and Wildlife, U.S. 101 286423 is open to all types of watercraft, including kayaks, canoes, rowboats, and small motorized vessels. However, larger boats may have difficulty navigating the shallow waters and narrow entrance to Dabob Bay.

Overall, U.S. 101 286423 appears to be a small, but serviceable boat ramp that provides access to a scenic and popular boating destination in Washington state.