Stringers

Hi everyone I am continuing to restore my Pedro 17 as I don’t want to sail her. She will be going up and down the river with a small outboard. I wanted to ask if anyone knows what type of stringers were used in her construction. The floor near her transom is slightly springing (very small area), and I want to reinforce it. There are no cracks in the fibreglass floor, she is dry and watertight. No external damage. Knowing it’s construction would help. Thank you.