Shore & Beach, Vol. 71, No. 4, 2003, pp. 7-12.
"Threes," an Unusual Surfing Spot at Shinnecock Inlet, New York
By
Frank S. Buonaiuto
Coastal Consultant
2 Dawnwood Drive
Manorville, NY 11949
Zeki Demirbilek, Nicholas C. Kraus
U.S. Army Engineer Research and Development Center
Coastal and Hydraulics Laboratory
3909 Halls Ferry Road, Vicksburg, MS 39180
,
ABSTRACT
Interactions among waves, tide, wind, jetties, and inlet morphology create and
enhance surfable waves within Shinnecock Inlet, New York. "Threes," a popular local
surf break, can be experienced only during certain combinations of incident wave height,
period, direction, and wind direction and tidal elevation. Threes is activated if waves
from the south-southeast to south-southwest propagate into the inlet, reflect first off the
east jetty, then off the west jetty, and break on a bayside shoal extending from the
western barrier island. In maintenance of the jetties at Shinnecock Inlet, the U.S. Army
Corps of Engineers tries to accommodate requests of surfers for preserving conditions
favorable for Threes. Observations indicate Threes can only be surfed around slack low
tide, when the tidal current velocity in the inlet is weak. The resulting waves can reach
approximately 1.5 to 2 m in height and plunge along the shoal for 20 to 30 m, giving a
surfing duration of 5 to 8 sec. In this paper, the Threes phenomenon is discussed and
successfully simulated with the CGWAVE numerical model. An implication is that
surfing amenities can be reliably designed with numerical models.
INTRODUCTION
Surfers often give descriptive names to surfing hot spots to denote the kind of ride
experienced. There are many such colorful names in the surfing subculture, including
"Jaws" in Maui and the "Pipeline" in Oahu, both in Hawaii, and "The Wedge" at the west
jetty of Newport Beach, California. Another interesting name is "Threes," referring to a
location at the bay side of the west jetty at Shinnecock Inlet, Long Island, New York.
Threes (Figure 1) owes its name to the waves incident from the Atlantic Ocean that
are twice reflected between two jetties, under certain circumstances as are discussed here.
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