For centuries, sailors used tree sap (pitch) to seal the spaces between the planks on wooden boats. Explain why pitch worked well as a sealant in this situation

Tree sap is a viscoelastic polymer, which means it's not really a solid but a very viscous (sticky) fluid. It's fluidity ensures that it can properly seal the spaces between the planks on wooden boats. Not only that, the pitch sap is hydrophobic - it is water resistant as well.