92 BFN with composite stringers?? Stringer problem

Just added a 92 Barefoot Nautique (Excel) to my fleet. It's a beautiful boat that has been running in Germany and France ever since it was originally imported from the US. Unfortunately it has just the 351 in it but it starts, runs and idles like brand new. Has about 1100 hours.

I bought the boat from a dealer that assured me that he checked all the stringers, floor etc.
When I got home I pulled the middle floor section to check the bilge. Had to notice a big crack in the left stringer lamination near the engine as well as a couple of smaller cracks. When looking into the big crack you can see some kind of black lamination!? Might this be some sort of extra layer of lamination or is my BFN actually one of the rare boats before 93 that already had the composite stringers? Any advice on fixing the cracks? I am not really looking for a full rebuild since I've just rebuild my Ski Nautiques engine and transmission.

I know that CC changed to composite stringers in 93 but also read about the fact that there are supposed to be a number of 91 and 92 boats with composite stringers that came out of the sea world and a few team skier boats (post by FL Inboards).

Haven't been able to check the foam yet to see if it's soaked.

Boats ID: CTC260780292

I don't think it's ever been proven that any Excel'ed hull boat was ever composite.This would be a good experiment   

Gary S wrote: I don't think it's ever been proven that any Excel'ed hull boat was ever composite.This would be a good experiment

I thought it had essentially been DISproven since a few 93+ excel inspections had revealed wood?

Just kill 2 birds with one stone. Core drill the rot section vertically down the stringer. If you pull sawdust or rot you have your answer. If not grind back the glass and repair it

Will drill the stringer core this weekend and also Check the foam to see if I have a major winter project. The boat feels quite heavy.

What your're probably seeing is black mold/rot on the wood.

I did find some time today to cut the fiberglass. As expected the stringer is completely wet and did already turn black. A second opening a bit further down the stringer did also reveal wet and dark wood. The Moisture meter of course shows overload.
I drilled into the stringer and luckily got some bright chips after about 0.08" dark chips.

It's no question that the fiberglass lamination on the stringer has to be completely removed in order to check the rest of the stringer and eventually replace it or at least let it dry.

Any suggestion if it's possible to keep the stringer when it's only a thin layer that turned black or am I looking for a full replacement?

I'm not 100% familiar with the BFNs structure yet but I guess the part I cut open does not belong to the main stringer but is some sort of support to mount the engine due to the wider beam of the BFN?