Me. Rev. Stat. tit. 10, § 3866

If the vessel has been already attached by a sheriff or the sheriff's deputy when a writ of attachment is issued for a lien claim, the writ of attachment must be served by the officer. If attached by a constable, the constable shall give up to the officer having the lien writ of attachment the possession and the precept upon which the constable attached it with the constable's return of the facts. The attachment holds subject to the legal priorities of the lien claim.