The current that runs northward along Florida’s east coast is officially named the Florida Current and not the Gulf Stream, a name most boaters tend to use. Call it what you will, whether bound for the Bahamas or headed to Mexico or Cuba either way this virtual river must be crossed.
The rule of thumb—do not to cross the Gulf Stream during a cold front—in other words when the wind is northerly. North winds create a terrible wind-over-tide effect in the Gulf Stream resulting in a motion that could be described as “putting your boat in a washing machine”. In addition, seas pile up on the Cuban coast making for extremely rough conditions at the entrances to ports and harbour. The entrances are often closed in a strong front. After a cold front has past the seas settle quickly and prevailing easterlies return. The best weather window for crossing the Gulf Stream to Cuba is to have easterly winds of 15 to 18 knots or less.
Your best strategy is to make the crossing during the night, when the winds tend to be light, and reach the coast of Cuba in the morning. The axis of the Gulf Stream will be encountered at approximately 50 nautical miles south of the Florida Keys here the current can attain a velocity upwards of 2.5 knots. The roughest part of this crossing will be approximately 10 miles before reaching the axis and 10 miles after you have crossed it especially if the wind is gusting. Don’t be concerned about compensating for the current. You can easily make back your westing in the morning close to the Cuban coast. Here, you may find a west flowing counter-current.
On our many crossings from the Florida Keys to Cuba, our strategy is this… we depart Marathon and cruise west through Hawk Channel. Our timing is such that we arrive off Key West just before dark. At sunset we head onto a course of about 203°T. In the morning, we awake to see the Havana skyline and then alter course to head for the fairway buoy off Marina Hemingway. We have made about 23 crossings and on a few occasions have detected no current in the Gulf Stream! The crossing from Marathon to Varadero is also easy when taken under the same favourable conditions.