Plan your Gulf Stream crossing to fit weather
3/22/2006 4:44:49 PM by Michael Lewis and Ken Millman
Ask one boater, and he’ll say crossing the Gulf Stream was such a calm trip he could do it in his sleep.
Ask another, and he’ll say it was so rough it made him swear off boating forever.
Neither is lying. And, that brings up an important consideration before taking a boat across the Gulf Stream: plan ahead, and go when the weather is right.
A good electronic navigation system, such as a GPS will help get you there, but playing and planning around the weather is the single most important factor when crossing the Gulf Stream. Basically, if the wind is blowing hard, the Gulf Stream can be one of the most dangerous places on the face of the earth. Especially in winter, when winds from the north blowing against the current can quickly create seas that can sink all but the sturdiest of vessels.
Most of the time though, trade winds from the east dominate the weather around the Gulf Stream. Unless they are overpowered by another weather system, they blow the year-round from a fairly steady 12 to 25 knots in the winter, to five to 15 knots in the summer.
Bad weather rarely blows in from the east during the winter, although during the summer a tropical depression or hurricane may move toward the Gulf Stream from the east.
Bad weather from the south is rarer and when it occurs it manifests itself as tropical depressions and other disturbances that form in the western Caribbean or lower Gulf of Mexico. Watch for these when crossing the Gulf Stream in May, June or July.
West winds are not common in the Florida area of the Gulf Stream, although when they do begin to blow, they are usually a prelude to unstable weather. In the summer, west winds may precede a period of light northerly winds and calms. In the winter, they usually warn of a coming norther: strong winds from the northeast to northwest. These are the most dangerous winds of all.
The key to understanding, and dealing with winds in the Gulf Stream, is to closely monitor weather stations on your boat’s VHF radio or by satellite radio.
Luckily, there are a number of excellent weather broadcasts in South Florida that give continual weather statements. Listen to them, and if the weather sounds at all chancy, don’t try crossing the Gulf Stream.
THE CURRENT
The other major problem faced when taking a boat across the Gulf Stream is the heavy current continuously pushing to the east in the lower Florida Keys and to the north around the Miami area. This current varies some in strength, but it will almost never move at less than 2 1/2 knots, and it can push along as fast as six knots.
We once delivered a 26-foot sloop from Marathon to Palm Beach, a voyage of about 160 miles. We covered that 160 miles in just over 15 hours, an average of about 10 1/2 knots. That little sloop couldn’t do more than six knots maximum, so we had more than four knots of current for that voyage.
For slower vessels, like sailboats and trawlers, which are in the grip of the current for long periods, it’s critical to calculate set and drift and make the necessary course adjustments. The following routes, figured for a cruising speed of five knots, include the set and drift corrections based on an average 2 1/2 knot current.
CROSSING ROUTES
There are six basic crossing areas for moving a boat across the Gulf Stream in the South Florida area.
• Between Florida and Freeport, Grand Bahama. This is the northern end of the crossing area, and while the voyage is not long, boaters encounter the strongest current. By and large, try to make a Florida/Grand Bahama crossing from as far south as possible. When bound from Palm Beach for Grand Bahama in a slow boat, steer 130 degrees true. This heading allows for the strong current in the Gulf Stream as well as the northwesterly current flowing along Grand Bahama Island from the Northwest Providence Channel.
Approaching Grand Bahama, which is low and difficult to see, the water tower at West End is the landmark. At night, the TV tower has a flashing red light that be seen from several miles. There is also considerable boating traffic and big tankers can usually been seen anchored or tied to the moorings offshore Freeport.
When going from Grand Bahama to the Florida coast (Palm Beach), steer 255 true. If heading further up the Florida coast, cross the Gulf Stream quickly until visual contact is made with the Florida coast, then follow it north rather than linger offshore in the Gulf Stream.
• Between Fort Lauderdale and Great Isaac Light. This is the crossing route normally used by sailboats heading back and forth to the Bahamas. Going east, steer 125 degrees true.
In night crossings, Great Isaac Light offers the advantage of having a big light visible 23 miles in clear weather. During the day, however, the tall, thin lighthouse and the pancake flat Great Isaac Cay can be tough to spot.
More noticeable are the anchored tankers and ships waiting their
turn to tie up at the refineries 35 miles to the north at Freeport. They anchor
on the 13-fathom shelf northwest of Great Isaac to take advantage of the shelter
that the Great Bahamas Bank provides.
Going from Great Isaac to Fort Lauderdale, steer 245 true. This is usually an easy crossing, and the only thing to be careful about is losing navigational aids and lights in the conglomeration of lights at night when approaching the Florida coast.
• Between Miami and Bimini. This is the narrowest place to cross the Gulf Stream, just under 45 miles. Here, the standard practice is to first sail down to Fowey Rocks, 10 miles south of Miami, to gain an edge on the strong northerly current. From Fowey Rocks, steer 115 degrees true for Bimini.
When approaching Bimini at night, look for the radio tower with its red lights. During the day, the first thing normally seen is fishing boats trolling offshore Bimini.
When going from Bimini to Miami, steer 240 degrees true. Try to leave Bimini early in the morning (3 a.m.) in order to make daytime landfall along the Florida coast. Nighttime approaches to Miami can be dangerously confusing due to the great numbers of lights on the coast.
• Between the Florida Keys and Bimini. This crossing is used primarily by yachts coming and going between the Bahamas and Gulf of Mexico. From the Keys to Bimini, jump off at Molasses Reef. From there, steer 90 degrees true.
Vessels coming the other way, southwest across the Gulf Stream, should attempt to cross as directly as possible, and then closely follow the reefs off the Florida Keys. From Bimini, steer 235 degrees true.
• Between the Florida Keys and the Cay Sal Bank (the extreme southwest Bahamas). This crossing is used by vessels that will then follow the Old Bahamas Channel along the north coast of Cuba.
I have been up and down the Old Bahamas Channel a number of times, and do not recommend it. The current is strong, there is a lot of large vessel traffic, and boaters always run the risk of tangling with Cuban military vessels.
However, if it’s necessary to use this passage, leave Key West and steer 150 degrees true. Coming the other way, from the Cay Sal area to the Keys, steer 295 degrees true, which will present a lower Keys landfall.
• Between the Florida Keys and the Yucatan Channel. Yachts sailing between Florida and eastern Mexico, or Florida and the western Caribbean use this route.
This is the longest crossing of the Gulf Stream, more than 250 miles from Key West to the middle of the Yucatan Channel (between Mexico and western Cuba). When moving from Key West to the Yucatan, the best thing to do is sail down the 65 miles from Key West to the Dry Tortugas (end of the Keys). From there, steer 245 true for 24 hours, then 215 degrees true. The concern here is to avoid being pushed onto the northwest Cuban coast by a clockwise, counter current that sometimes circulates there.
Coming the other direction, from the Yucatan to the Florida Keys, first steer 0 degrees true for 12 hours to get away from Cuba. Then steer 80 degrees true for 24 hours. Finally steer 25 degrees true. Depending on the current and winds, this series of courses will place you into the Florida Keys somewhere around Key West.
In closing, remember that the courses given in this article are based on slow boats, sailboats moving at five or six knots, and slow powerboats. Faster vessels will have to adjust recommended courses.
Further, no one can predict the variances in wind and current, so when crossing the Gulf Stream, always allow for potential variances. And, monitor the weather. If it looks bad, don’t go.