In case a quick look has given you the idea I`m asking after the boat, you`re wrong. Not sure but it seems a DIY job on perhaps what was an old wood cabin on a steel shell. Whatever the construction I think someone has made them self a nice home.
So focus on the wooden gantry to the rear of the boat.
Some of the ropes are to give support to the wooden gantry but another is for raising and lowering the brown box.
The pipe emerging at the bottom is plastic and my first thought was what is in there that needs draining?
Now my thoughts and suggestions to follow but please throw some ingredients into the mixing bowl.
It can`t be a fridge as the sun would bake whatever you put in side.
Maybe they heard about Jaq`s dessert eating dog and it`s their dessert cooler like Squirrel proof bird feeders.
My guess is it`s a solar water heater like the camping ones Here. Men when you click the link remember the deal is the water bag only.
So say the box is lined with a black waterproof liner, as appears to be at the top, and has the pipe attached. Would the water inside get hot enough being in the box?
If it is a solar water heater is the pipe just to perhaps fill a bowl to do the dishes or to have a wash. I can`t imagine someone standing under it having a shower.
Looking closer i think the box is metal not wood so yes it would heat up water inside.
Over to you.