STANDARD

Floating Debris & Flotsam

Identifying and avoiding partially submerged logs, fallen trees, and floating hazards in Prince William Sound.

The Threat of Floating Debris in Prince William Sound

Because of the massive, dense forests of coastal hemlock and spruce lining the shorelines of Prince William Sound, fallen trees are a frequent and serious navigational hazard. Heavy winter storms, landslides, and high winds continuously wash trees, large root balls, and beach logs into the ocean.

Critical Hazards for Mariners

1. Waterlogged Logs (“Deadheads”)

As logs float in saltwater over weeks or months, they become water-soaked.

  • The “Deadhead” Hazard: A fully waterlogged log loses its buoyancy and rides extremely low in the water. Often, only a few inches of wood or a small branch breaks the surface, while the massive trunk floats vertically just beneath the water line.
  • The Threat: Deadheads are nearly impossible to spot on radar, in rough chop, or when driving into the sun. Striking a water-soaked log at cruising speed can shear off an outboard lower unit, puncture a hull, or flip a kayak.

2. High-Tide “Flotsam” Re-float

Massive piles of logs, branches, and woody debris (known as flotsam) accumulate naturally on gravel beaches and in the corners of bays.

  • The Re-float Hazard: During extreme high tides (spring tide cycles or storm surges), the rising water reaches high up the beaches, lifting these accumulated debris fields back into the water.
  • The Threat: Within hours, a clear bay can become choked with thousands of floating sticks, logs, and root balls.
  • Action: Exercise extreme caution and reduce speed when operating in the Sound during or immediately after the peak of an unusually high tide cycle.

Preventative Navigation Tactics

  • Station a Bow Lookout: When navigating in woody areas or during high tides, station a passenger at the bow to scan the water continuously. Turn off the autopilot and steer manually.
  • Reduce Speed in Low Visibility: Slow down significantly when operating in fog, rain, heavy chop, or during twilight, as debris becomes invisible under these conditions.
  • Scan for Rebound Wakes: Debris often collects along tide lines and currents. Watch for lines of foam, seaweed, and floating matter on the surface—these lines almost always contain hidden logs.
  • Be Mindful After Storms: Strong winds wash new debris off the steep mountain slopes. Treat the days following a major storm as high-risk for floating hazards.