We have recently purchased our Troll 530 (2105 vintage) and have discovered rain pools on the roof due to the bow, both fore and aft as well as side to side. As far as I recall we never had this issue with our previous Troll 530 (2006 vintage). I have spoken to Cameron at A/L where we purchased the van and he said Hymer were aware, have researched it and it is cosmetic only.
Has anyone else experienced the issue and had any problems please?
I have included a photo with a straight edge across the roof to show the extent of the indent.
My concern is that if it bows any further the interior of the roof will come into contact with the inside fixings and furniture.
DSCF1546.JPG - Bild entfernt (keine Rechte)

I once met a chap onsite with a Triton that had a bowed roof, his main issue was that it collected so much water that it made the roof compress on the springs which made the water shoot off and keeping him awake all night.

Try a hose pipe on the roof to make sure you don't have the same problem, I believe the bow came to light with Hymer not storing the roofs flat before installation.

You have no trim on the bottom edge of the pop top ?

As it was bought "as is", I think you will find that this over rides any fitness for purpose, but still worth a go.
Dave

can't see how that could be cosmetic, if its bowed inwards when it should be outwards, it will then hold a pool of water which could then freeze over winter

Where exactly on the roof is it ? Where in relation to the pop top ? Can you take a picture from the bedroom window ?