UNDERSTANDING THE CONTINENTAL SHELF AND BATHYMETRY OF THE EAST COAST

Surfline user Jeff writes: “Atlantic southern hemi swells in the north east have always intrigued me. I have surfed some long period southern ocean stuff while growing up at the beach breaks in NJ. These swells were usually closed out or if we were lucky some wind swell helped cross it up a bit. More recently I have learned from living on the west coast that breaks with deep underwater canyons offshore, like Blacks or Palos Verdes, can focus this energy to maximize the swell’s potential. Are there any such breaks on the east coast that have similar characteristics for focusing long period energy?

Seems to me that the long drawn out continental shelf on the east coast just prevents anything like what we see at Blacks on nice SW from ever happening.”

Hi Jeff,

Although in general we do have a pretty substantial continental shelf, we still have to contend with areas of underwater bathymetry that affect our swells. Also, there are some regions where the continental shelf is really narrow – near the south Outer Banks and there is also almost zero shelf near Palm Beach in FL.

So we do see areas up and down the East Coast where refraction can and does occur with our swells – robbing one beach of energy while another beach gets the goods. Even in NJ surfers have to be aware of the offshore Hudson submarine canyon – yes this absolutely will affect the surf in NJ and along western LI. Some beaches in NY/NJ will be better than others as a direct result of this canyon affecting the swell (dependent upon sell direction and period).

So while it seems that we do not see much affect to our swells from underwater bathymetry, it does occur, although not quite like the case you get with a spot like Black’s. Hope this helps.

Best regards,

Mike Watson

Surfline Forecaster