Coastal Passage Planning: A Practical Guide for Yacht Owners

A coastal passage — anything from 50 to 200 miles between safe harbors — is the kind of trip where small planning errors become big problems. You can't just turn around easily, you can't anchor casually, and weather changes carry weight. Most boating distress calls along the U.S. coast involve passages that weren't planned thoroughly enough.

This is the framework we use. Adapt to your boat, route, and crew.

Step 1: Pick the route, not just the destination

Two boaters going from Marina A to Marina B 75 miles up the coast can take very different routes. Considerations:

• Coastal hop vs. straight-line: stay within 5 miles of shore (lots of harbors of refuge, weak ocean swell) vs. cut a straight line across a bay (faster but exposed).
• Inlets vs. continuous coast: routes that require crossing an inlet at slack water are timing-locked.
• Traffic: routes that thread between commercial shipping lanes need careful timing and lookout.
• Underwater hazards: known wrecks, shoals, and submerged rocks. Even outside ICW, the chart matters.
• Bridges: opening times and clearances. Many bridges have specific opening schedules.

Map the route in your chartplotter or chart software with waypoints at each course change. Print a backup paper chart with the route penciled on. The chartplotter will fail at the worst possible moment; the paper backup costs $30.

Step 2: Calculate the schedule

For each leg, estimate:

• Distance (nautical miles)
• Speed at your planned cruising RPM (NOT max speed; account for sea conditions and fuel burn)
• Time = distance ÷ speed
• Fuel burn at cruising RPM
• Daylight available

Add up the pieces:

• Total time = sum of leg times + buffer for unexpected delays (15–25%).
• Total fuel = sum of leg fuel + 1/3 reserve. Never plan to arrive with less than 1/3 tank.
• Cross-check daylight: ideally arrive at any unfamiliar harbor before sunset.

A real example: 75 nm at 7 knots cruising = 11 hours running. Plus 1.5 hours buffer = 12.5 hours. Departing 0500 puts arrival around 1730, which gives daylight margin in summer but not in October. Plan accordingly.

Step 3: Get the weather forecast — read carefully

Pull the marine weather forecast for the entire route, the entire trip duration, plus 12 hours after arrival.

Specifically check:

• Wind speed and direction throughout the trip
• Wave height and period — is it building or diminishing?
• Frontal passage timing — fronts always bring wind shifts and squalls
• Convective storms — afternoon thunderstorm risk
• Tide and current — especially at any inlets

Two acceptable scenarios:

1. Forecast is benign for the entire passage with comfortable margin.
2. Forecast deteriorates AFTER you arrive — you'll be safely tied up.

NOT acceptable: forecast deteriorates 4 hours into a 12-hour passage with no harbor of refuge in between. Reschedule.

Step 4: Identify harbors of refuge

For every leg of the route, identify the closest harbor you could divert to if conditions change. For each refuge, know:

• Entrance conditions (channel depth, dangers)
• Daylight needed for safe entry
• Whether it has fuel, repair services, anchorage
• VHF channel of the marina or anchorage

Mark these on your chart. If something goes wrong at hour 5, you're already 30+ miles from your destination — knowing exactly where to bail out matters.

Step 5: File a float plan

A float plan is a simple document you give to a trusted person ashore. It includes:

• Vessel name, registration number, description
• Captain and crew names with contact info
• Departure date/time, route, destination, ETA
• Communication plan (when to call/text)
• Action to take if you don't check in (call USCG)

USCG provides a free template at floatplancentral.uscgaux.info. Send it to a friend or family member before you leave the dock. Confirm you've arrived as soon as you tie up.

This is one of the cheapest, most powerful safety steps in boating. The Coast Guard cannot help you if they don't know you're missing.

Step 6: Pre-flight the boat

The day before:

• Check oil, fuel filter, fuel-water separator
• Verify bilge pumps work (manual + auto)
• Check raw water strainer
• Inspect dock lines, fenders, anchor and rode
• Test VHF — radio check on channel 9
• Confirm GPS and chartplotter are loaded with the route
• Check life jackets, flares, fire extinguisher, first aid kit
• Top off water and fuel
• Know how the engine sounds at cruising RPM right now (so you'll notice when it changes)

The morning of:

• Final weather check (often updates between forecasts can shift the picture)
• Final fuel check
• Brief crew on plan, harbors of refuge, and abort criteria
• Walk the deck for loose items
• Check engine and look in bilge before starting

Step 7: Define the abort criteria — written down

Decide before you leave under what conditions you turn around or divert. Examples:

• "If sustained wind exceeds 25 kt, divert to [Refuge X]."
• "If sea state increases to 6+ feet, turn back."
• "If we're more than 1 hour behind schedule at the halfway point, divert."
• "If anyone is incapacitated by seasickness, divert immediately."
• "If we will arrive after sunset at unfamiliar destination, anchor at [Refuge Y]."

The reason to write these down is that judgment under stress is unreliable. The captain who's been driving for 6 hours, hasn't eaten, and watching the weather build is not in a good frame of mind to make new strategic decisions. Pre-decided rules eliminate the choice — you just execute the plan.

During the passage

• Run the engine at cruising RPM, not maximum. Burn rate increases dramatically above cruise; reliability drops.
• Note the time at each waypoint. Track your speed-made-good vs. plan. If you're slow, you'll arrive late.
• Monitor the bilge. Look every hour. A leak gets bad fast.
• Listen to the engine. Changes in tone, vibration, or smell are early warnings.
• Watch weather. Listen to NOAA Weather Radio every 1-2 hours.
• Stay rested. On longer passages, rotate watches so the helm is always alert.
• Eat and hydrate. Mistakes happen when blood sugar is low.

After arrival

1. Confirm with your shore contact that you arrived safely.
2. Note in a log: weather encountered, fuel burn, any issues. Useful for future planning.
3. Don't immediately start working on the boat — rest first. Mistakes from fatigue happen at the dock too.

Successful passages aren't accidents. They're the product of preparation, conservative decision-making, and the discipline to wait when the weather isn't right. The captains who do this well are the ones who get to keep doing it.

For shops that can handle pre-passage maintenance and inspections, browse our marine service directory.