Common fabrics for the sailor would be wool, linen, or fustian. For gentleman, brocade silks, fine linen, high quality wools, etc. Often, the finest materials would be used for the front panels with the rear panels and sleeves being made from lesser quality materials as these would not show. See links page for sources. The coat of the period is collarless and fairly long as well.
Pictorial references show coats that go to about the knee or slightly above.
The sleeves of the coat seem to go to about mid forearm and the cuffs are wide and turned back to almost the elbow. Also, both sides of the tails in the back have fake button holes down them. The pockets are functional and seem to be set low on the coat. The pocket flaps, however, are not functional in the sense that they are never button closed, though they have fake button holes. As with the waistcoats, common fabrics for a sailor's coat would be wool, linen, or fustian.