Albert Barnes Commentary 1 Kings 22:48

"Jehoshaphat made ships of Tarshish to go to Ophir for gold: but they went not; for the ships were broken at Ezion-geber." — 1 Kings 22:48 (ASV)

The expression “ships of Tarshish” likely refers to a specific class of vessel, similar to the ships the Phoenicians used for trade with Tarshish (Tartessus; 1 Kings 10:22). This is comparable to how “Indiaman” was used to describe a certain type of large merchant ship.

Jehoshaphat’s fleet was constructed at Ezion-Gaber on the Red Sea (2 Chronicles 20:36), the same place where Solomon had previously built his navy (1 Kings 9:26). As the overlord of Edom, Jehoshaphat had the right to use this harbor.