If you find a server with a fresh wipe, it will be a race against time to get to the tugboat before other players do. Each Harbor holds TWO Tugboats. The first step is to identify the location of each harbor. To do this, hold 'G' to open your map and find the areas marked as harbors.

Once you've located a harbor, start your journey: walk, run, pilot, drive, ride, or swim to the harbor. Upon arrival, check the area for a Tugboat.

If you don't see a Tugboat:
Skip to Part B.

If you find a Tugboat:

Board the boat and head to the Wheelhouse.
Locate low-grade fuel and crude oil.
Hold 'E' on the dashboard to access the fuel tank and add the fuel.
Start the ship.
To build on the Tugboat, authorize yourself using the dashboard. You can then place various items on the boat, though not all items can be placed. Make sure to install a door and a lock to secure your new ocean vehicle from pesky pirates (players).
https://steamuserimages-a.akamaihd.net/ugc/2531667816640338736/17C968F143372AAAD4165A65A5F68F58CED0540B/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false
For additional information, skip to Part C!

If you can't find an unclaimed Tugboat, look for one that another player has captured and start breaking down the door using tools. Here are the details for each door type and the tools you can use to damage them:

Wood Door (EASY) https://steamuserimages-a.akamaihd.net/ugc/2531667816640406329/7E58A0116D84034372C5D143E4D10A3C49217681/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false
HP: 200
Tools to Use:
Hatchet
Pickaxe
Salvaged Sword
Explosives
You can basically use anything

Sheet Metal Door (MEDIUM) https://steamuserimages-a.akamaihd.net/ugc/2531667816640406046/1ECACA625E8FD49EEDBBDCD1AC439C4C2582FF6A/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false
HP: 250
Tools to Use:
Satchel Charges
Beancan Grenades
Salvaged Sword (less effective)
Explosives
It's Resistant to Melee and Fire Attacks

Armored Door (HARD) https://steamuserimages-a.akamaihd.net/ugc/2531667816640404987/6D9B52A4BF4BD883B4606107234CC82C8E5507BF/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false
HP: 800
Tools to Use:
Timed Explosive Charge (C4)
Rocket Launcher
Satchel Charges (less effective)
Explosives
Prepare for a challenge, especially with the more fortified doors!

VERY IMPORTANT
Prepare for Your Ocean Journey:

Make sure to have doors, locks, fuel, and weapons on standby. The ocean provides a valuable resource: red barrels filled with 5-9 low-grade fuel and 15-18 crude oil. This crude oil can be refined into low-grade fuel using an oil refinery. For every crude oil container, you can produce 3 units of low-grade fuel.