Repainting the coach roof

[AleCiotti]

Hi guys, due to water infiltrating where the coach roof and the teak deck attach, I will have to open a big portion of the coach roof up and also of the teak deck to remove the rotten wood..

After that I will have to re-paint the surface, my boat coach roof coat is of
white polyurethane paint, I never applied it and I have no idea on how to proceed

should I sand all the old paint first? should I use a primer (I guess so)?
is there a specific way it should be applied?

Thanks in advance, I'll link some photos of the boat for reference.

[coopec43]

Is there any water getting inside the yacht or is it sitting on the f/g deck where it rots the teak?

(Make sure you have an approved face mask when you sand the coach-house)

[psk125]

Decide what paint you are going to use and follow their directions.

[Franziska]

Ideally apply a layer of fiberglass with epoxy over the wood first.
Filler with epoxy filler. Then follow with 2 component polyurethane undercoat and follow up with two layers of two component polyurethane paint.