A Boat Torch is a craftable Item in the Shipwrecked DLC. It is made with 2 Twigs and 1 Torch. It can be used to provide light on a Boat, other than the Log Raft and the Raft which have no slots for Boat Lights. Boat Torches must be attached to a boat and turned on to provide light. It can be turned off to preserve its fuel. It cannot be refueled, and will disappear when its fuel is consumed.
A better alternative to the Boat Torch is the Boat Lantern which has a durability of 7 min 48 sec.
Crafting does not recognize an item's durability. Thus, using a torch with 1% durability works as well as a new one, and is a more efficient use of resources.