Can I replace hollow stringers w/ plywood?

I'm working on restoring a 1964 Starcraft Belle Isle 16'. The previous owner ripped out the deck and stingers and I'm having trouble figuring out the new stringer layout. I believe that the old stringers were hollow fiberglass and it looks like the floor was 3/16" ply. My question is, can I do the new stringers in 3/4" laminated ply and if so is there any suggestions on the layout? It's little difficult to plan without seeing how it was originally done.

 

Welcome to the forums Jason.
Given the age of the hull my bet would be that the stringers were wood or open cell foam covered with a "top hat" of FRP (which leaked and why they got torn out). Given the pictures it looks like there would have been several transverse plywood floors (i.e. vertical members across the bottom of the hull to keep it in shape) to support the decking. Without closer pictures and measurements it is kind of hard to say what went where, but by reading Chapters 2 and 3 of the book below you can get a very good understanding of how it was probably assembled.

Marine design manual for fiberglass reinforced plastics : Gibbs & Cox : Free Download, Borrow, and Streaming : Internet Archive https://archive.org/details/marinedesignmanu00gibb

 

Boats of that time were rarely engineered, they were slapped together and if they broke more chop was added.

All you need to do is take your best guess at what was there and put supports back in the same place. Whether you use plywood or hollow stringers makes no difference.

 

Indeed, you can use one material or another, or another, if you wish. But in each case you will have to adopt solutions that are different depending on the material used.

 

Neat old boat!

Some pics of one more put together, click on the icon '7' and the rest of the pictures will show up:
Vintage Starcraft Belle Isle https://www.michigan-sportsman.com/threads/vintage-starcraft-belle-isle.696441/

Is is apparent in the boat where the plywood for the sole (floor) came installed from the factory? 3/16" (4.75mm) seems thin for this.

 

As @ondarvr said, it probably wasn't engineered. In which recreating the original layout is a waste of t&m. Design it properly, using Gerr's Elements of Boat Strength and the incredible resource which is this forum, and you will make a better boat than the original builder.

You may not realize it, but the fine gentlemen who have already replied,and will reply are heavy hitters of such caliber that I am often humbled (temporarily - anyone with the balls to ride a dachsund into cavalry combat is uncrushable. Like a tick)