Dunbar Door

I like looking at fishing gear, doors come in all shapes and sizes and are used to keeps the trawl nets open as they are towed through the water. They stand up right in the water and this type would rub along the sea bed as it is towed along. You can see the right hand side which is the bottom has a strip welded to it to prevent excessive wear on the door.
On the left hand side or top you can see a little pod that was originally painted blue. A sensor is placed in it prior to deploying the  fishing gear. It will work in tandem with sensors on the other door and on the middle clump. This information will be displayed in the wheelhouse and will inform the skipper that the fishing gear is spread correctly and fishing efficiently.