Background: to create a dugout, you hew a hole in a log then light the scattered wood shavings to harden and hollow out the watercraft. Once the dugout is lit, it can no longer be adventure>lifted.
So how do you lift a burning dugout?
It's pretty simple. If instead of using a firebrand/torch/matches on the dugout itself to light it, one can pick up the unburnt dugout and use it on a Fire Pit. You can then carry around the fiery vessel as your very own large and hazardous torch.
Okay, but why does it matter?
Here's where the fun starts: with it lifted, you can then place the burning dugout where it doesn't belong. If it is placed inside a liftable container such as a Garden Shed or Cart, it then can't be removed until the dugout is done burning (or maybe at all?).
The most compelling way this bug could be abused has to do with Rowboats, since the 2 cargo slots of a rowboat can also be used to house passengers. You see, Hafen combat is all about mobility, fleeing, and traveling great distances, often in boats. With burning Dugouts, you can temporarily render both passenger slots of a rowboat completely unusable. If you and two friends attend a combat encounter in a single rowboat, your adversary would only need some wood and stone to ruin your escape craft and trap you on land.
There are other possible problems from this though. Imagine you're looting a base in your knarr, and its occupants toss a bunch of un-removable dugouts in your cargo slots so you can't steal their chests. There are probably many more implications I haven't considered.
How should this bug be fixed?
Three workable solutions: make unburnt dugouts unliftable, make lit dugouts liftable in general so they won't get stuck in rowboat slots, or better yet make it so unburnt dugouts can't be used on fire sources to light them.
Making this burn the boat/cart it's placed in would be funny but maybe not as easy.