Just took a closer look at the chart I referred you to. It's produced by the Army's Institute of Heraldry and doesn't include certain awards peculiar to the naval service but it should suit your purpose.
The service for which campaign or service medals were issued is minted into the obverse (face) or reverse of the medal. Many lump all decorations, medals, ribbons, badges and insignia into one general catagory "medals" so there's a chance that what you have is a set of his service ribbons. These will be mounted individually or in rows of two or three. Check what you have against the chart and any you can't identify get back with me.
You may have a Navy Good Conduct Medal. The service and suspension ribbon is a solid, dark, sort of wine-colored red. The medal is inscribed "Fidelity - Zeal - Obedience" on the obverse and his name may be engraved on the reverse.