The ship had an overall length of 240feet, a beam of 23.5feet and a draught of NaNfeet. She was powered by 2 triple expansion reciprocating steam engines, driving two shafts, which developed a total of 7403ihp and gave a maximum design speed of 27kn. During the trials the contract speed was exceeded, and the vessel was clocked at 27.25kn. Steam for the turbines was provided by two double-ended Yarrow boilers. Alagoas carried a maximum of 140LT of coal that gave her a range of approximately 3700nmi at .
The ship mounted two 4abbr=onNaNabbr=on guns in single mounts. In addition, four 47 mm (3pdr) cannons in single mounts were deployed at the time of launching.
The official full speed trial for Alagoas took place on November 26, 1909 on the Skelmorlie deep-water measured mile at the mouth of the Clyde. During a continuous three hour run with a 100 ton load, the ship exceeded her contract speed of 27 knots.[2]