The lack of access to a metal lathe, I had to find a temporary solution to lock the hatch from the inside. As the pictures shows it works also as a lock during daytime. I used a bit of an old hinge combined with a plate from IKEA kitchen hanging rail system, the round plate. Therefore, the holes in the base plate. In this context they have no effect. The white is a piece of furniture paw from IKEA that is split in two just to not to scratch the door (even if everything is sanded). It is not optimal to use a padlock at night if something should happen so I'm working on a solution where I can use a fast sprint that can be removed quickly ... but only from within.
 

1. The lock plate and the standard pin.

2. Same from a different angle.

3. In order to lock the hatch from inside; Pull the hatch so the hole for the pin is on the inside and insert the pin.
 

4. Open the hatch again and insert the round locking plate from the inside.

5. Use a padlock and insert it first through the locking plate and then through the pin...

6. ...and close the padlock. Or as we do, we just slip the rubber tube around the padlock  littel bit higher so the clasp cant move to the sides.
 

7. From the outside of the boat the locking is pretty much the same.

8. Now it will be impossible to slide the padlock underneath the hatch and open it.