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Old 10-11-2013
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Re: Miami to Bimini

Quote:
Originally Posted by Melrna View Post
Quote "Your prescription makes no sense and would have one's track over the ground equivalent to sailing along the hypotenuse of a triangle and then down the vertical leg" That is true and correct. It makes sense when you apply VMG vector charts
This is from both my experience and the Explorer Charts preface in crossing the Gulf Stream at 90 degrees. My first time I did a set and drift and it took me over 14 hours from No Name Harbor. Subsequent crossing I average around 9-10 hours. I agree sail south of the rhumb line until you get into the Gulf Stream usually around 5-8 miles of shore in the Miami and Bimini area. You cannot beat a 3-4 knot current and get any VMG (velocity made good) by set and drift going around 5-6 knots boat speed. Furthermore, you do not want to spend any more time in the Gulf Stream than you have to due current and most important the short choppy waves that normally prevail. It is not called a "Dirty Patch of Water" for nothing.
The Gulf Stream(GS) is around 43 miles wide here in the Miami area. Average boat speed say is 6 knots for this discussion. Rhumb line is 47 NM. The average time in the GS 7 hours straight line. 7 hours in the GS will equate to around 14 NM up stream (north) using 2 knot average. Depending on where you start your trip will depend far north you will be of Bimini. So let say worst case you are 14 NM north of Alice Town that is around 2:15 + 7 = 9.15 hours total trip time.
If you set and drift your VMG will only be around 2.5-3.5 knots depending on the GS current strength. (38-50 degrees X-track). Simply math says it will take around 16 hours (average 3kts). Sixteen hours in the GS.. Not good.
The prevailing winds here are from the East. So sailing to Bimini unless you want to take 24 hours tacking into the Gulf Stream is not doable. Like I said the heading to Bimini is around 110 degrees. So this makes it a motorsail at best. Every time I hold this course I end up at the north end of Bimini island. 45 -60 minutes later I am in Alice Town.


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Yep. The description of this method as described in the Explorer chart books should be required reading for anyone navigating across the Gulf Stream. It amounts to an S course, always maintaining a right angle to the current, not trying to fight it to some percentage as you would in a nav101 current vector course.
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