Fine linen with broidered work from Egypt was that which thou spreadest forth to be thy sail; blue and purple from the isles of Elishah was that which covered thee. Fine linen - שש shesh, cotton cloth. In this sense the word is generally to be understood.
To be thy sail - Probably the flag - ensign or pennant, is meant.
Blue and purple from the isles of Elishah - Elis, a part of the Peloponnesus.