A momentary lull between breaking waves, favorable for launching a boat.
A lull in a high windstorm.
[Variant of slack1.] In New England a slatch can be a lull between breaking waves or a lull in a high windstorm. Its use is recorded as far back as the 17th century: "Whan it hath beene a sett of foule weather and that there comes an Interim . . . of faire weather . . . they call it a little Slatch of faire weather" (Nomenclator Navalis). Occurrence of the word in both its senses, formerly in Britain and now in New England, attests continuous use down through the centuries of the Old English word slæc, which is pronounced today as it was in Old English. Slæc is also the source of modern slack, the relationship of slatch and slack being evidenced in the use of slatch in 17th-century nautical parlance to denote the slack part of a rope or cable on a ship.