The Avaril was a Yrythny starship in service in the 24th century that was larger than a Defiant-class vessel and had a crew of one thousand eight hundred.
In 2376, the Avaril carried the USS Defiant to Vanimel within a large storage bay after the Defiant was damaged by Cheka weaponry. Elias Vaughn later saved the Avaril from the Cheka warship Ston'yan by using a Yrythny shuttle to fool the Cheka into believing the shuttle was another Yrythny vessel. (DS9 - Mission Gamma novel: This Gray Spirit)