The cupboard fronts (in kitchen and head)on my boat are 4mm marine ply which has cracked and has water marks. Behind the timber sheets is smooth fibreglass which the sheets were glued to. I've removed the sheets and old glue (which resembles shoe glue). Now ready to replace the sheets but unsure what glue to use. Has anyone done this? If so what glue did you use?
thanks.

The old glue sounds like the yellow contact glue. I would be inclined to use one of the Polyurethane glues like Sikaflex 291. I was in Bunnings Friday to buy some but it's no longer in stock there. I bought the Bostik version of the same. I'm sure there are numerous glues now to pick from.

liquid nails is the answer to (almost) all problems

cheers,