Standard mix for marine epoxy is 2% hardener by weight, or roughly 20 ml hardener per litre of resin. Always measure by weight if you can — volumetric measures are less accurate as resin viscosity changes with temperature.
Can I apply this on a wet surface?
No. The repair surface must be dry, sanded, and free of contaminants. Moisture trapped under the laminate will continue to spread the damage and cause the new repair to fail within months.