 The Royal Navy temporarily assigned a young constructor , Stanley Goodall , to C & R to assist in this task . Goodall brought a copy of the plans of Hood and accurate accounts of shell damage at the Battle of Jutland . In addition , a senior U.S. constructor who served on Admiral Sims 's staff in London , L.C. McBride , became privy to much British experience and was able to share it with C & R. While C & R worked concurrently on the more conventional , more heavily armed and armored South Dakota @-@ class , it quickly adopted and incorporated ideas from Hood into the Lexington project which included a reduction of the main armor belt , the change to " sloped armor " and the addition of four above @-@ water torpedo tubes that were added to the four underwater tubes that had been included in the original design . Other changes included a widening of the ship to allow for an adequate torpedo protection system and an increase in vertical belt armor to 7 inches ( 180 mm ) . Another improvement in boiler technology reduced the number of boilers to 16 and the number of funnels to just two , but increased the normal displacement of the ship to 43 @,@ 500 tons , 300 tons more than the South Dakota class and 10 @,@ 900 tons greater than the previous battleship class , the Colorado class . 
