Crossing the Gulf Stream: Route Planning

Crossing the Gulf Stream from Florida to the Bahamas by boat takes more planning than most passages. The current will push you north the entire time you’re in it, your heading and your actual course will never match, and if you don’t account for all of that before you leave the dock, you’ll end up somewhere you didn’t intend to be.

I remember how confused I was the first time I tried to work this out before our 2016 crossing. A friend who had made the trip many times sat down with me and walked me through it in plain language. That’s what I’m going to do here.

Understanding the Gulf Stream

The Gulf Stream is a river of warm water inside the Atlantic Ocean. Between Florida and the Bahamas, it runs north. Between Florida and Cuba, it runs east. It typically averages 2 to 2.5 knots.

If you leave Florida and head due east (90 degrees), every hour you travel you will move east at your boat speed AND north 2 to 2.5 miles. That northerly push is an average. You’ll move more in the center of the stream and less at the edges. But the average is what matters for route planning.

A few things make the Gulf Stream more demanding than a typical passage:

• The warm water generates more thunderstorms than the surrounding ocean
• It carries heavy commercial ship traffic heading up and down the East Coast
• Smaller boats are constantly crossing between Florida and the Bahamas

Crossing as quickly as possible reduces your exposure to all three of these.

Here’s a live current map showing the Gulf Stream right now:

You can learn how to read it in detail in Gulf Stream Location, Speed and Counter-Currents.

Before you leave, also make sure you have a solid weather window lined up. Any northerly wind component turns the Gulf Stream into dangerous, steep chop. Picking Weather Windows covers exactly what to look for.

Two Terms You Need to Know

Heading is where the bow of your boat is pointing. It’s what shows on your ship’s compass and what you set on the autopilot.

Course over ground (COG) is the direction the boat is actually moving across the water. It’s what your chart plotter shows.

In the Gulf Stream, these two will never be the same. Your COG will always be north of your heading because the current is pushing you north the whole time.

Understanding this difference is the foundation of all Gulf Stream route planning.

How to Plan Your Route

The goal is to leave from a point far enough south of your destination that the current sweeps you right to it. Here is the math, using a real example.

Step 1: Measure the east-west distance.

Measure only the east-west component between your departure point and your destination. Not the diagonal distance between the two points. Just the east-west distance.

In our example, we were thinking of leaving from Angelfish Creek and heading for Gun Cay. The east-west distance was 53.2 miles. (Note: Angelfish Creek is only suitable for shallow-draft boats. We draw 3 feet.)

To figure this with a real-life example of leaving from Angelfish Creek:

Step 2: Calculate how long the crossing will take.

Divide the east-west distance by your average boat speed without current.

Our average speed is about 6 knots, so: 53.2 miles / 6 knots = about 9 hours.

Step 3: Calculate how far north you will be pushed.

Multiply the hours by the Gulf Stream’s average speed. I use 2.5 knots as my planning figure, which tends to work well as a conservative estimate. Check the current map to get a feel for real conditions on your planned departure day.

9 hours x 2.5 knots = 22.5 miles north.

Step 4: Find a departure point that far south of your destination.

In our example, we needed to leave from a point about 22 miles south of Gun Cay. But Angelfish Creek is only about 15 miles south of Gun Cay. Even at 2 knots in the stream, that’s 18 miles of northing. It might not work.

So I looked at alternate destinations on the Bahamas side instead. There are several anchorages up to 28 miles north of Gun Cay. I marked the most appealing ones and planned for multiple possible stops depending on how far north we actually got pushed.

I always plan alternate destinations before any Gulf Stream crossing. If weather turns rough, if the trip takes longer than expected, or if sunset is closing in, having options already plotted and evaluated makes all the difference.

The result on that trip: we made better-than-expected time and came in right at Gun Cay, with a bit of counter-current on the Bahamas side helping us along.

Your Heading Must Never Point South

For a fast crossing, one rule applies on every eastbound crossing: your heading should never go south of due east (90 degrees).

Any amount south of due east and you’re fighting the current. We discovered this the hard way: turning just two degrees south of due east dropped our speed over ground by more than half a knot. A few more degrees south and it dropped nearly a full knot. Do not fight the Gulf Stream.

The same principle applies on the return trip: your heading should never go south of due west.

Tips for the Crossing

Start with a clean bottom. A clean hull is one of the best things you can do before you leave. Faster speed means less time in the stream, which means less northing and less exposure to traffic and weather.

Motor or motor-sail at your best cruising speed. Pure sailing across the Gulf Stream is a dream. It’s rare to get conditions that allow a fast crossing under sail alone. If you do have engine trouble and have to slow down, plan for more northing than your math predicted and have alternate destinations ready.

Ships are faster than they look. You will almost certainly have to cross, duck, or wait for commercial traffic somewhere in the stream. Speeds are deceptive out there. Be very cautious about trying to cross in front of another vessel.

If you have to pause, head south. If ships are coming from both directions at once, slow down and turn south briefly. Simply cutting speed lets the stream keep sweeping you north. Ships in the Gulf Stream typically run 20 to 25 knots and will be past you quickly.

Have your documents in order before you go. See the Bahamas Checklist for the full list of what you need for entry, including the customs decal, MMSI requirements, and quarantine flag.

Crossing from Miami or Fort Lauderdale to Bimini

Bimini is actually south of Miami. That creates a specific problem: to reach it, you either fight the current all the way across, or you allow the stream to push you north and then make your southing on the Bahamas side.

Neither option is easy. Both add hours to the trip.

The better third option is to use your weather-waiting time to move south to a different anchorage before you cross. Which one depends on your draft.

If heading south first is not practical, my preference is to cross due east and make any necessary southing on the Bahamas side. The Gulf Stream usually does not run right to the islands, and there is often a counter-current on the east side. Cross the stream, then turn for your destination.

If you decide to fight the current, you can set waypoints as usual and steer to follow the rhumb line. Be aware that your speed over ground will likely be at least a knot below your typical average. Plan the timing accordingly.

Crossing from the Keys

If you are starting further south, say from Rodriguez Key at Key Largo, the planning is the same. Figure the east-west mileage, divide by your average speed to calculate how far north you’ll be pushed, and mark that point due south of your destination on the chart. Your steering heading should be slightly less than 90 degrees to keep you near the rhumb line as the stream pushes you north throughout the trip.

Because a Keys-to-Bahamas crossing is longer, the math is a less perfect estimate. Expect to tweak your heading in real time as you see how conditions develop.

Westbound Route Planning (Return Trip)

The return from Bimini to Florida is planned the same way, just in reverse. You want to leave from a point south of your Florida destination so the stream pushes you toward it rather than past it.

On our return, we could not start as far south as the math called for. The Bimini chain does not extend that far south. Our options were to fight the current or get across quickly and handle the southing inside Hawk Channel on the Florida side.

We chose to cross fast. Here is how we added a useful twist: we used a day with northeast winds (not good for crossing) to work south along the Bimini chain to Riding Rock. A counter-current helped. That got us about 15 miles further south than leaving from Gun Cay, putting us only about 4 miles south of Angelfish Creek on the Florida side.

Creating Multiple Westbound Routes

I created a series of potential westbound routes for the various places we might cross the Florida reef and enter Hawk Channel, including routes I thought were unrealistically far south and north. I planned them all before we left.

We steered due west as we crossed. The chart plotter only shows one route at a time, so I started with the southernmost one. As the stream pushed us north of that rhumb line, I pulled up the next route north, and so on. We crossed the reef, entered Hawk Channel, and sailed south to Angelfish Creek.

We would have covered fewer miles fighting the stream. But I don’t think it would have saved us much time, and we got out of the stream, its traffic, and its weather far more quickly.

Ready to Make the Crossing?

The Gulf Stream is just the beginning. Once you’re through it, there’s a lot more to work out: where to clear customs, how to handle Bahamas paperwork, provisioning, communications, weather while you’re there, and how to move around the islands. My course Get Ready to Cruise the Bahamas walks you through all of it step by step, so you can prepare before you leave and just enjoy the trip once you’re there.

For on-the-water reference, the Bahamas Cruising Guide puts anchorages, entry ports, tides, and services in a table format built for fast lookup.

Get Ready to Cruise the Bahamas:

• Course from our store

Bahamas Cruising Guide:

• Spiral bound or PDF from our store
• Spiral bound on Amazon
• Kindle on Amazon

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