ICW Navigation: Shoaling, Bridges and the Markers That Matter

The Intracoastal Waterway stretches over 3,000 miles along the Atlantic and Gulf coasts, offering protected passage from New England to Texas. Navigating this ribbon of water demands attention to shoaling, bridge schedules, and marker interpretation that differs from open-water sailing.

Understanding ICW Markers

ICW markers follow the standard red-right-returning rule, but “returning” means heading south on the Atlantic ICW and west on the Gulf ICW. Green markers stay to port, red to starboard when following this convention.

Yellow squares and triangles distinguish ICW markers from local channel markers. When ICW and local markers conflict, follow the yellow. This becomes critical where the ICW crosses busy commercial channels.

Dealing with Shoaling

The ICW shoals constantly. Channels that showed adequate depth last season may now have sand bars. Active Cruisers forums and Waterway Guide updates provide current reports, but nothing replaces careful depth watching.

Time your transit of notorious shoaling areas for high tide. Georgia’s Altamaha Sound, numerous cuts through North Carolina, and sections of the Texas ICW regularly catch boats. Local knowledge from marinas and other cruisers proves invaluable.

Bridge Protocol

ICW bridges range from 65-foot fixed spans to restricted-schedule openings. Know your mast height and add a margin for tide and waves. Download bridge schedule apps or consult Waterway Guide for opening times.

Approach restricted bridges with speed to arrive at opening time, not early. Holding position in current while waiting for an opening tests boat handling skills and patience. Call the bridge tender on VHF 13 if unsure of protocols.

Planning Daily Runs

ICW cruising rewards moderate daily distances. Plan for 40-60 miles per day to allow time for bridge delays, shoaling detours, and enjoyable stops. Pushing hard leads to arriving at unfamiliar anchorages in darkness.

The ICW experience improves when you embrace its slower pace. Shore-side towns offer provisions and restaurants. Fellow cruisers share intelligence about conditions ahead. The protected water lets you cruise comfortably in conditions that would keep you harbor-bound offshore.