Pilot Cutter Deck
HI the sealer is called G4 and can be obtained from garden centres selling ponds, and from glass fiber suppliers.
I would try on a test piece of your chosen planking as it will highlight any glue on the surface.
An alternative is any good clear varnish for use outside or as Alan says sanding sealer. The result will be similar and glue stains will not be highlighted.
The sealer is excellent on hulls where you want to achieve a high finish and can be overpainted or sprayed with the colour of your choice.
Dave
Live long and prosper
Dave