Complex sentence: Until the 15th century, the Portuguese were limited to coastal navigation using the barque and the barinel (ancient cargo vessel used in the Mediterranean), fragile small boats that possessed only one mast with fixed quadrangular candle.
Split into simpler sentences: Until the 15th century, the Portuguese were limited to coastal navigation using the barque and the barinel (ancient cargo vessel used in the Mediterranean). These boats were small and fragile; and possessed only one mast with fixed quadrangular candle.