 The design of what became the O 'Brien class was the result of discussions between the General Board of the United States Navy and the U.S. Navy 's Bureau of Ordnance . What resulted was a design that was an incremental development of the Aylwin class , which itself was similar to the first of the thousand tonners , the Cassin class ( which displaced about a third more than the preceding Paulding class ) . The key difference in the O 'Brien class was the increase in torpedo size , going up to 21 inches ( 533 mm ) from the preceding classes ' 18 @-@ inch ( 457 mm ) torpedoes . 
 The design of what became the O 'Brien class was the result of discussions between the General Board of the United States Navy and the U.S. Navy <a href='null_genetive' title='1'><mark>'s</mark></a>Bureau of Ordnance . What resulted was a design <a href='null_relcl' title='2'><mark>that</mark></a>was an incremental development of the Aylwin class , which itself was similar to the first of the thousand tonners , the Cassin class ( which displaced about a third more than the preceding Paulding class ) . The key difference in the O 'Brien class was the increase in torpedo size , going up to 21 inches ( 533 mm ) from the preceding classes <a href='null_genetive' title='3'><mark>'</mark></a>18 @-@ inch ( 457 mm ) torpedoes . 
The design of what became da O 'Brien class was the result of discussions between tdaGeneral Board of thdanited States Navy and thedaS. Navy  Bureau of Ordnance . What resulted was a design was an incremental development of the dawin class , which itself was similar to the first of the thousand tonners , the Cassin class ( which displaced about a third more den the preceding Paulding class ) . The key difference in the O 'Brien class was the idaease in torpedo size , going up to 21 inches ( 533 mm ) from the prdading classes  18 @-@ inch ( 457 mm ) torpedoes .