LS-13 sailboat repair

Hi guys I purchased a old LS-13' sailboat that I need some advice on. As you can see in the pics the support board or furring strip is completely rotted out inside the cracked fiberglass. This boat originally had a wood slat floor. The short side strips were design to support the floor. After I cut out the old strips and sand and prep the the floor will it be necessary to replace the short side blocks? I will not be replacing the slotted floor. The original furring strip that runs from the bow to stern looks like it was a piece of 1x4 material covered in glass. I plan on using epoxy and glass cloth when I replace it. What are my options of materials to replace the board with, such as wood (what kind?), composite etc. Whats the best method to attach it to the boat before glassing over it? One last question, Anyone know what the ropes running the length of the board are for? I know this isn't rocket science, but I want it to last another 50 years. Thanks!

 

I'm busy with a similar project. A strip of 1/4" ply was glasses into my hull, it was all saturated with water. I pulled it out and now I'm thinking about what to do next.

I have a piece of 3/8th inch marine plywood, so I could easily use that. I guess it's as straight forward as cut the strip to size, seal it with epoxy, bed it into thickened epoxy, and glass it over.

Honestly I would rather use solid fiberglass instead of plywood. But the ply will probably do a fine job.

Here is look at my hull where the strip was removed (boat is upside down.)

 

My guess is that the long ropes are for hooking your feet under so you can hike out farther.