Winger Zane Crook was again thirsty for work until an injury forced him to leave the field in the 20th minute. Starting fullback Tamati Samuels lasted three minutes before collecting a game-ending injury.
Crook and Marshall scored the Bay's tries and first five-eighth Adam Blake kicked two penalties.
The Hawke's Bay Tuis remain winless with one game remaining in the women's NPC.
Defending champions Auckland Storm ran in 13 unanswered tries during a 73-0 drubbing of the Tuis at Auckland's Western Springs on Saturday. The Tuis host Manawatu in their final out of the season this Saturday at Napier's Park Island.
The Hawke's Bay Under-13s were walloped 55-0 by their Wellington counterparts in Eketahuna on Saturday.
Wellington led 36-0 at halftime. Busy No8 Cameron Huata and Nick Hutton were the best of the Bay forwards while first five-eighth Lincoln McClutchie and second five-eighth Josh McIntyre were the pick of the Bay backs.