A ship grounding in a very low tide (neap) is still said to be neaped.
So we have spring tides regularly once a fortnight, with neap tides in between.
When the two conspire, they cause a spring tide; when the solar and lunar tides are opposed, we have the neap tide.
Height of neap and spring tides, at full and change of the moon.
Hence the difference between high and low water is only half as great at neap as at spring tide.
The spring tide is lunar plus solar; the neap tide is lunar minus solar.
The water rises fifty feet with the spring tides, and twenty-five with neap tides.
When the two agree, we get a spring tide of four feet; when they oppose each other, we get a neap tide of only two feet.
One of the vessels out of which ale was drunk was the Saxon nap, now the neap, or nip, out of which we drink Burton ale.
During the neap tides, the ship lay wholly aground, the sea not approaching nearer than within a hundred yards of her.
Middle English, from Old English nepflod "neap flood," the tide occurring at the end of the first and third quarters of the lunar month, in which high waters are at their lowest, of unknown origin, with no known cognates (Danish niptid probably is from English). Original sense perhaps is "without power." As a noun from 1580s.