46 C.F.R. § 141.360
(a) A towing vessel must carry lifebuoys as follows:
(b) Each lifebuoy on a towing vessel must:
(c) Lifebuoys must have the following attachments and fittings:
(1) At least one lifebuoy must have a lifeline, secured around the body of the lifebuoy. If more than one lifebuoy is carried, at least one must not have a lifeline attached. Each lifeline on a lifebuoy must: