Lipari 41: Why is our bow much deeper in the water than stern?

[bomel]

On our FP Lipari the waterline is at the stern much higher (20cm above the water) than on the bow (5cm above the water). We investigated a lot but could not find any reason for the behaviour. Possible reasons we thought of:
1) Uneven loaded
It looks like if the boat is uneven loaded (much heavier in the front), but there is no significant extra weight in the bows. The bow lockers are empty. The stern also is not lighter than normal. Even if we remove the 75m chain and the anchor it makes only 2-3cm.
2) Water in the bows
I believed that the sealed bow tanks (below the lockers) are filled with foam for buoyancy and that this foam could be wet. But then I checked by drilling a hole: these tanks are empty and not filled with water. Shouldn't there be foam in there?
3) The antifouling waterline was not correct projected. But this matches with the decorative stripes originally from FP.

Do you have any ideas what causes this behaviour?
Does anyone else has the same on his boat?
Thank you.