s and fathoms (6 feet = 1 fathom) for offshore. Numbers with a tiny underline (e.g., 1̱4) are drying heights — they're above water at mean low water. The number tells you how high the rock or shoal sticks up at the lowest normal tide. ### 2. Depth Contours Curved lines connecting points of equal depth. NOAA charts draw contours at 1, 2, 3, 5, 10, 20, 30, 60, 100, 200, and 400 fathoms (or feet, depending on chart). Closely spaced contours mean steep drop-offs — prime fishing but also prime grounding risk. ### 3. Rocks - A solid asterisk ✳ or * = rock that's always visible (above water at all tides) - A hollow asterisk ✳ (open center) = rock that covers and uncovers with the tide - A dotted asterisk = rock that's submerged at all tides - A plus sign + = dangerous rock, often with depth noted nearby When in doubt, treat every asterisk as if it's a plus sign. Reef and rock damage is the single most common insurance claim for recreational boats under 30 feet. ### 4. Wrecks A fishbone symbol (ƜƜƜ) is a wreck. A dotted fishbone is a dangerous wreck that may be near the surface. Wrecks less than 20 meters deep in charted depths over 30 meters are considered hazards to navigation and have their own symbol set. ### 5. Channel Markers Red triangles with a number = port-side markers (returning to port from seaward). Green squares with a number = starboard-side markers. The mnemonic is **"Red Right Returning"** — keep red on your right when coming back to port. Channel markers are numbered from seaward toward the harbor. So if you're seeing marker #2, you're closer to the ocean; marker #14 means you're deep in the channel. The numbers alternate red/green as you progress. ### 6. Buoys A diamond shape with a small circle inside represents a buoy. The color and label inside the diamond tell you what kind: - RG = red and green (junction buoy) - Y = yellow (special purpose) - C = cautionary ### 7. Lighthouses A magenta circle with a black dot in the center, often with a radiating flash pattern. The chart will also list the light's characteristics: color, flash pattern, period, and range. ### 8. Restricted Areas Areas outlined in magenta with a label inside: - Restricted = entry limited (often military) - Prohibited = no entry - Caution = navigational hazard or naval activity - Security Zone = Coast Guard-enforced exclusion (around naval vessels, ports) ### 9. Anchorage Areas A magenta dashed circle or rectangle labeled Anchor or Anchorage. Inside these areas you may anchor; outside, anchoring may be prohibited or restricted by time. Our [anchoring in wind and current guide](/blog/anchoring-in-wind-and-current) covers how to actually set the hook once you've picked a spot. ### 10. Submarine Cables A magenta line with the label Submarine Cable or a hatched line. Anchoring or trawling near these is illegal and will earn you a Coast Guard visit — and a bill if you snag the cable. ### 11. Traffic Separation Schemes Arrows on the chart showing the direction of vessel traffic in busy shipping lanes. Small boats should cross traffic schemes at right angles (perpendicular), not run along them. ### 12. Magnetic Variation A magenta line with a small compass rose at intervals, labeled with degrees east or west of true north. This is the difference between magnetic north (what your compass reads) and true north (what the chart is drawn to). You must apply this correction when plotting courses — see [Wikipedia's article on magnetic declination](https://en.wikipedia.org/wiki/Magnetic_declination) for the underlying physics. ## How to Plot a Course on Paper Here's the absolute minimum procedure for plotting a course on a paper chart: ```text 1. Identify your departure point (A) and destination (B). 2. Draw a straight line from A to B with a pe

How to Read a NOAA Chart: A Practical Guide for New Boaters