What is one of the longitudinal ribs or ridges on the barrel of a capstan or a windless; -- usually in the plural; as, the whelps of a windlass called?

whelp — (Naut.) One of the longitudinal ribs or ridges on the barrel of a capstan or a windless; -- usually in the plural; as, the whelps of a windlass. (Webster's 1913.)

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