daphneNYCDusk

Sandy Hook – The Lighthouse That Moves

Teresa Carey Words 4 Comments

daphneNYCDusk

Daphne southbound through New York Harbor at dusk looking for a suitable anchorage

 

I had been warned about  the swirling currents of Hell Gate, but it was the profusion of lights from ships, shore and navigational aids that overwhelmed me as I entered Lower New York Harbor after sunset in search of an overnight anchorage. Most of the harbor is wide open to the wind and swells coming in from the Atlantic, but Sandy Hook, a narrow point of land that extends north into the harbor, offers sufficient protection for the southeast corner of the bay. I turned my bow south and looked for the Sandy Hook lighthouse.

Set against the surrounding Jersey Shore, Sandy Hook is an oddity. It is a long and narrow barrier spit, nearly six miles long and one mile wide. I looked at the chart and wondered why the lighthouse was in the middle of the spit and not on the end.

As it turns out, when it was first built in 1764, the Sandy Hook lighthouse actually was on the northern end of the spit. However, as the sand around it shifted over time due to  longshore drift, the lighthouse moved miles inland.

Longshore Drift is a current that travels parallel to then shoreline. At Sandy Hook, it carries sand from the inland end of then spit and deposits it on the shore, extending the spit long  past where the lighthouse stands.

LongShorDrift_Point-web

Only two things need to be present to create the energy that drives the current: waves and gravity. The wind generates waves, which approach the shore and are pushed up the beach at the angle of wind direction. When the waves retreat, gravity pulls the water straight down the beach slope. The waves approach and retreat at differing angles, creating a net flow sideways along the shore. Erosion from the waves traps sand in the current and moves it along with the water until the current reaches the end of the land and loses energy. Any sand particles that were suspended in the water are deposited there.

That is how Sandy Point came to be. After some time, the barrier spit was long enough to become a navigational concern for ships, so a lighthouse was built near the end of
it. Then as the years passed, longshore drift continued to carry sand along the shore and deposit it at the end of the spit, extending it 1.5 miles farther into the bay.

sandyHookChart

The Sandy Hook Lighthouse as seen on the NOAA chart, about 1.5 miles from the tip of the spit.

 

This Sea Science Article originally appeared in SAIL Magazine December 2012.

Comments 4

  1. Long ago

    Without question, the currents in that area are difficult. When I was a much younger, my father was into boating, not with sailing vessels, but cruisers. At one point, we had a 1935 Richardson, and navigated under the Varrazanno-Narrows Bridge twice before we ever drove over it! One reason it was difficult, in addition to what you mentioned, is that the Hudson River had so many dangerous items floating/submerged, that it was a a bit dicey. I remember the Ambrose Lighthouse/ship. We went up through the locks to Lake Champlain those many years ago (40 or so?).

    Earlier this spring, hubby and I decided to take a peak at the lasting effects of Hurricane Sandy at “ground zero, ” first visiting Sandy Hook. In years past, my family docked the Richardson at Atlantic Highlands; all that is left of the piers are pilings! With a different boat, we docked at a marina further down the coast. They seamed to have fared better.
    We were never live aboards, but we did take two, two week vacations aboard, spent every two week vacation and summer weekend aboard, and one entire summer at the dock. Does that count? :-))

  2. Dawn jones

    No sailing knowledge or navigational input, but need to comment on the stunning picture. Lady Liberty always fills me with pride. I cannot wrap my mind around how many others have viewed her from that distance at that time of day. ;). Happy, safe travel to you three.

  3. Ante Mazalin | SailingEurope

    Great post Teresa. In the example of Sandy Point lighthouse we can see the power and beauty of mother nature 🙂

  4. Dorothy Mammen

    I wondered the same thing as we sailed from the Verrazano Bridge toward Sandy Hook on September 16 — why the lighthouse was so far from the end of the spit — now I know the answer! Nice explanation, Teresa!

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