Thanks for all the comments.
I think the best plan is to remove the 1/32" water damaged deck and replace.

As it's 1:32 ply and if the water has penetrated then I believe you have no option other than to remove the whole deck and recover. Ply of the same thickness would be the easiest to use and planks marked as per the original. Removal will require some care and I would work from the mid points of the decks and chisel them away up to the edges. If you have a vibrating saw this would help remove the majority of the wood. You may need to add some stringers to mount the new deck .Once recovered with new wood the model should be good for another 50 years.
dave976

Does the superstructure lift off? Reason I'm asking that if it doesn't it will be difficult to fit planks along the front of the front cabin and there isn't much clearance to the underside of the potholes.

I've used 5 x 0.5mm Tanganyka planks from Cornwall Model Boats on a couple of my Faireys at 31" and 33" but did the planking off model on thin ply sheet as I was bending them.

Finished with International Paints Schooner varnish.

Chris

If you do decide to plank it. I used 1/32" thick, 1/8" basswood strips on this model. You can use a width that matches your scale. I put it down with titebond III wood glue. Spar varnish for the clear coat. It can be stained any color or left natural. Hope this helps. Thanks, Dave

Sand down to clean unmarked surface then reinstate lines before a coat of satin Varnish.