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+# Sailing Quick Reference
+
+---
+
+## Points of Sail
+
+The point of sail describes the angle between the boat's heading and the true wind direction.
+
+| Point of Sail | True Wind Angle | Description |
+|---|---|---|
+| In irons | 0–30° | Head-to-wind, sails luffing, no drive |
+| Close hauled | ~30–45° | Sailing as close to the wind as possible |
+| Close reach | ~45–60° | Between close hauled and beam reach |
+| Beam reach | ~90° | Wind directly abeam — often fastest point |
+| Broad reach | ~120–150° | Wind on the quarter — comfortable, fast |
+| Run | ~150–180° | Wind from directly behind |
+
+**No-go zone:** ~0–30° on either side of the wind — the boat cannot make progress sailing directly into the wind.
+
+---
+
+## Tacking vs. Gybing
+
+**Tacking** — turning the bow through the wind (bow crosses the wind). The boom swings across from one side to the other. Used to head upwind.
+
+**Gybing** — turning the stern through the wind (stern crosses the wind). The boom can swing violently — always control the mainsheet. Used to change direction downwind.
+
+---
+
+## Sail Trim Basics
+
+**Telltales** — strips of yarn or fabric on the sail.
+- Both telltales streaming aft → sail trimmed correctly
+- Windward telltale lifting → sheet in (trim), or bear away
+- Leeward telltale lifting → sheet out (ease), or head up
+
+**In irons fix:** Let sails luff, push boom to one side, fall off onto a tack.
+
+**Reef** — reducing sail area by partially lowering the mainsail and tying off the excess. Reef before you think you need to. Typical thresholds: first reef ~15–18 kt, second reef ~21–25 kt.
+
+---
+
+## Hull Speed
+
+The theoretical maximum displacement hull speed:
+
+**Hull speed (kt) ≈ 1.34 × √(waterline length in feet)**
+
+| LOA | Hull Speed |
+|---|---|
+| 20 ft | ~6.0 kt |
+| 23 ft | ~6.4 kt |
+| 30 ft | ~7.3 kt |
+| 40 ft | ~8.5 kt |
+
+A modern fin-keel boat can exceed hull speed in planing conditions (surfing downwind in big waves).
+
+---
+
+## Navigation Lights — Quick Reference
+
+| Situation | What You See | What It Is |
+|---|---|---|
+| Red + green + white | Two side lights + stern | Head-on approach |
+| Red only | Port sidelight | Vessel crossing left-to-right in front of you |
+| Green only | Starboard sidelight | Vessel crossing right-to-left — you are give-way |
+| White only (masthead) + green | Overtaking from starboard | Vessel overtaking you on starboard |
+| Two white (stacked) + red/green | Two masthead lights | Large ship (≥50 m) underway under power |
+| Red + white (all-round, vertical) | Not under command | Give way — vessel cannot maneuver |
+| Green + white (all-round, vertical) | Trawler | Give way — engaged in fishing |
+| White all-round only | At anchor | Avoid — vessel at anchor |
+| White + red all-round (vertical) | Pilot vessel | Pilot boat on duty |
+
+---
+
+## Day Shapes
+
+| Shape | Meaning |
+|---|---|
+| ⚫ Black ball | Vessel at anchor |
+| 🔻 Black cone (apex down) | Sailing vessel motorsailing |
+| ⚫ ⚫ Two balls (vertical) | Not under command |
+| ⚫ ◆ ⚫ Ball-diamond-ball | Restricted in ability to maneuver |
+| ▬ Black cylinder | Constrained by draft |
+
+---
+
+## Beaufort Wind Scale
+
+| Force | kt | Description | Sea State |
+|---|---|---|---|
+| 0 | < 1 | Calm | Mirror smooth |
+| 1 | 1–3 | Light air | Ripples |
+| 2 | 4–6 | Light breeze | Small wavelets |
+| 3 | 7–10 | Gentle breeze | Scattered whitecaps |
+| 4 | 11–16 | Moderate breeze | Moderate waves, frequent whitecaps |
+| 5 | 17–21 | Fresh breeze | Long waves, many whitecaps, spray |
+| 6 | 22–27 | Strong breeze | Large waves, spray, whitecaps everywhere |
+| 7 | 28–33 | Near gale | Sea heaping up, foam streaks |
+| 8 | 34–40 | Gale | Moderately high waves, edges blowing |
+| 9 | 41–47 | Strong gale | High waves, dense foam, visibility affected |
+| 10 | 48–55 | Storm | Very high waves, sea white, heavy sea roll |
+| 11 | 56–63 | Violent storm | Exceptionally high waves |
+| 12 | 64+ | Hurricane force | Air filled with foam, visibility nil |
+
+---
+
+## Common Knots
+
+**Bowline** — fixed loop that won't slip. The classic sailing knot. "The rabbit comes out of the hole, round the tree, and back down the hole."
+
+**Cleat hitch** — securing a line to a cleat. Take a round turn around the base, then two figure-8 turns, then one locking hitch over the horn.
+
+**Clove hitch** — temporary attachment to a post or rail. Two half hitches; easy to adjust and release.
+
+**Figure-eight** — stopper knot. Prevents a line from running through a block or fairlead.
+
+**Round turn and two half hitches** — secure, adjustable attachment to a ring or rail.
+
+**Reef knot** — joining two lines of similar diameter. Right over left, left over right. Not for critical loads — use a sheet bend for mismatched diameters.
+
+**Sheet bend** — joining two lines of different diameter. The thicker line forms the loop.
+
+**Rolling hitch** — attaching to another line or spar under load. Grips when pulled along the spar.
+
+**Anchor hitch (fisherman's bend)** — the correct knot for attaching a line to an anchor.
+
+---
+
+## Buoyage — IALA System B (Americas, Japan, Philippines, Korea)
+
+**Red right returning** — red buoys on the starboard side when returning from sea.
+
+| Mark | Shape | Color | Top Mark | Meaning |
+|---|---|---|---|---|
+| Port lateral | Can / pillar | Red | None | Keep to starboard (IALA-B: keep red to starboard) |
+| Starboard lateral | Nun / cone | Green | Cone | Keep to port |
+| Safe water | Sphere | Red + white vertical stripes | Sphere | Safe water on all sides |
+| Isolated danger | Pillar / spar | Black + red bands | Two black balls | Isolated danger, safe water around it |
+| Special mark | Any | Yellow | Yellow X | Special purpose (mooring, racing, TSS) |
+| Cardinal (N) | Pillar / spar | Black over yellow | Two cones pointing up | Pass to the north |
+| Cardinal (S) | Pillar / spar | Yellow over black | Two cones pointing down | Pass to the south |
+| Cardinal (E) | Pillar / spar | Black-yellow-black bands | Cones base-to-base | Pass to the east |
+| Cardinal (W) | Pillar / spar | Yellow-black-yellow bands | Cones point-to-point | Pass to the west |
+
+*IALA-A (Europe, Africa, most of Asia):* Red/green assignments are reversed — "red left returning."
+
+---
+
+## VHF Radio Channels
+
+| Channel | Use |
+|---|---|
+| 16 | **International distress, safety, and calling** — always monitor |
+| 22A | US Coast Guard working channel |
+| 9 | Boater calling channel (US) |
+| 6 | Ship-to-ship safety communications |
+| 13 | Bridge-to-bridge (1 watt) |
+| 70 | DSC digital selective calling — do not use for voice |
+| 24, 25, 26, 27, 28 | Public correspondence (marine operator) |
+
+**MAYDAY procedure:**
+1. MAYDAY MAYDAY MAYDAY
+2. This is [vessel name × 3]
+3. MAYDAY [vessel name]
+4. Position
+5. Nature of distress
+6. Number of persons aboard
+7. Any other information
+8. Over
+
+---
+
+## Tide and Current Basics
+
+**Flood** — tide coming in (rising sea level).
+**Ebb** — tide going out (falling sea level).
+**Slack** — the period of minimal current around high and low water.
+
+Rule of twelfths — tide rises/falls unevenly:
+- Hour 1: 1/12 of range
+- Hour 2: 2/12 of range
+- Hour 3: 3/12 of range ← fastest
+- Hour 4: 3/12 of range ← fastest
+- Hour 5: 2/12 of range
+- Hour 6: 1/12 of range
+
+**Spring tides** — larger range; occur near new and full moon.
+**Neap tides** — smaller range; occur near quarter moons.
+
+---
+
+## Distress Signals (Rule 37 / SOLAS)
+
+Any of these signals indicate distress and request assistance:
+- Red parachute flare or red hand flare
+- Orange smoke signal
+- MAYDAY spoken over radio (Ch 16)
+- SOS (···−−−···) by any signaling method
+- Continuous foghorn sound
+- Gun fired at approximately 1-minute intervals
+- Flames on the vessel
+- Slowly and repeatedly raising and lowering both arms
+- Square flag with ball above or below it
+- Orange dye in water
+- Satellite EPIRB signal