Cape Hatteras:  A Consideration of Strategy

 (Based on a sailboat delivery of June 2006)

 

Cape Hatteras is a well designed boat trap I just narrowly escaped; while I had heard stories of it’s dangers  and I knew to avoid it in north winds, nowhere have  I found  a succinct description of it’s dynamics for a sailor.

  The Gulf Stream, moving north along the North Carolina coast, turns east at about 35° 14’ north. From the cape itself (N 35° 14’, W 75° 30’)   Diamond Shoals  (very shallow, shifting) extends ESE 14 miles. The Stream often brushes the shoal. That is: the Stream runs north till it gets approximately to Cape Hatteras, where it runs off east to warm Europe. Very shallow water extends from the cape itself  to about 15 miles offshore; sometimes the Stream runs directly up to these shoals, but generally the western wall of the Stream is a few miles offshore of the shoals. Sometimes the Gulf Steam  extends north of the cape before turning east.

     The problem:  sailing in the Stream in a north wind (contrary to the current)  you will find yourself in a very steep short-wavelength sea. If you persist  to the latitude of the shoal you will not be able to escape west  ( the shoal)  or east  ( many miles of this sea on your beam – as you are staying in the stream as it moves offshore) and you’re trapped. If you pass the cape moving north and turn west you risk being driven back onto the shoal by the wind.  A south flowing cold current  along the coast above Hatteras adds to the danger.

   I rode the Gulf Stream north from Key West in a 50 foot sailboat, making good time. Approaching the northward  turn of the Stream off  Cape Lookout I was getting headed from the north , and, concerned about fuel, went into Morehead City. While there I was told the Stream was fine in 5 to 10 kt  north winds, and heard reports from NOAA that predicted just that; in addition I  lost one crew member and another told me any delay would force him off the boat.

   I went out again and pushed north through the night into a building wind;  morning found us  in 15 to 20 knot gusts. I had been in the middle of  two very different NOAA predictions all night, and the weather had made up it’s mind. The boat was slamming off the waves and burying the bow. I pushed on to about  34°  58’ , looking for the north wall of the Stream. At one point I looked ahead  to see only a building sea and miles of standing 10 foot waves, got smart and fell off to the west , eventually finding  myself in the lee of the shoals and the cape,  and turned SW back toward Cape Lookout; this took several hours. We almost broached to several times here.

  NOAA predicted SW winds the next day, and I thought of waiting in the area. The fin-keel boat I was in failed to heave-to well, and I had heard that Ocracoke inlet was too shallow for me to enter. I’ve since spoken to captains local to the area , and was told this was not true, that the Ocracoke  cut was well marked and could predictably accommodate up to a 7 foot draft. I don’t know this for a fact. Calls to the Coast Guard confirmed that  Ocracoke is not federally maintained nor is the Hatteras cut, but Oregon Inlet (north of the cape) is. Oregon however shifts and fills continuously; the Coast Guard’s response is to post survey data at  http://www.saw.usace.army.mil/nav/OREGON.htm

  We returned to Morehead City, refueled, watched the wind turn west and then  southwest, and returned toward Hatteras  This time I did not go offshore into the Stream but sailed directly toward a point 5 miles east of the abandoned lighthouse at 35° 09’,  75° 17’ . The   SW wind  did not lay the sea down; we still had 4  foot following seas, but it was far safer than two days prior. I was pleased to see the light tower off to my west; this was the crux, and after several miles NE I turned NW, found the coast, and ran N a few miles off the beach; the absence of waves was very pleasant. I had been told at Morehead City that running close to the beach was an effective strategy  to escape the south flowing Labrador Current (as called by a captain at Morehead City; I’m not sure one can use that name this far south ), and of course as the wind was just off the beach there was no fetch.

  An added problem here is the absence of harbors of refuge. There is nothing between Morehead City and the Oregon cut above the cape (about 160 sea miles ) From Morehead City  to  Virginia Beach is about  240  miles.

  Again , consider the nature of this trap if the wind turns north . You have to commit to the passage from a distance, so weather from just NOAA VHF will be dated  when you arrive and thus can’t be seen as reliable. If coming from the north with a north wind you’ll have a following sea till the north wall of the Stream and then you’ll be in the standing waves of the Stream. If you try to run west now,  you’re on the breakers of the shoal, and east  would be  days of  some of the  worst seas you can imagine. There is more to this issue; I’m still ignorant of the general characteristics of the south moving coastal current; it’s width, general distance from the shore, and speed.

  If you’re annoyed by my vagueness allow me to quote from the US National Ocean Service’s Coast Pilot “Cape Henry to Key West” , chapter  3  : “…the currents are subject to wide variation …at times the Gulf Stream has great velocity, at other times none will be found….on nearing 35° 05’ N, 75° 19’ W …the current is reported to set well to the ENE and at other times nearly north”.  SO YOU CANT TELL where the north wall is !  The navigator is thus left guessing about important variables.

  Thermal images from satellites providing  useful plots of the Stream can be seen at

http://marine.rutgers.edu/mrs/sat_data/ ; as I examined one for the 8th of June , the day we passed Hatteras , I see an intrusion of colder water south of the lighthouse, and this would explain  the relatively high seas we encountered with the SW wind.

     One solution  would be  to stay out to sea. If traveling north and wanting the push of the Stream, stay in the eastern side of it so you can bail out further into the Atlantic if things turn bad. Real time weather information  on a large scale ( so one can verify NOAA VHF )  and the ability to download recent charts of the Stream is vital. Another solution  is the ICW, which I no longer distain. Another is to work more  in one’s garden, which is  where I’m headed  now.

Arthur Heyman - 6/14/06

arthur@networks-cc.com

  A good site for wall positions here and (better on a slow link)  here