Mount an engine in boat | Chapter 2 - New Beginnings DI Riptide Guide
Last update: 11 May 2016
Pick up boat engine exit workshop and head for the boat. You'll surely run into new zombies. You can throw engine at them (it won't be damaged) and then finish them off.
When you get to the boat, stand where the engine should be and press Action key. Mission ends right now. Listen to radio talk with Harlow, what unlocks new main quest.
Attention - Remember that for completing the main quest, you get a Reward. So don't forget pick up Shillelagh from Harlow when you see her next time.
Main quest unlocked: Pathfinders (quest is automatically unlocked after finishing the described mission).