(b) Tangible Property.

If tangible property is to be attached or arrested, the marshal or other person or organization having the warrant shall take it into the marshal's possession for safe custody. If the character or situation of the property is such that the taking of actual possession is impracticable, the marshal or other person executing the process shall affix a copy thereof to the property in a conspicuous place and leave a copy of the complaint and process with the person having possession or the person's agent. In furtherance of the marshal's custody of any vessel the marshal is authorized to make a written request to the collector of customs not to grant clearance to such vessel until notified by the marshal or deputy marshal or by the clerk that the vessel has been released in accordance with these rules.