How do you know if stringers are bad?

[Skoot]

Im looking at is a 1971 19-6, 100% original except for a new gas tank.  The deck has a few small softspots, otherwise in great condition for its age.  After reading many post on this site it seems most of you replace/redo the stringers once the deck is removed and you have a better idea of whats going on.  Im hoping some of you can answer a few questions for me.
1. Is there anyway off knowing the condition of the stringers without cutting out the floor?
2. How do I determine if they are any good/water logged etc.
3. What problems could i run into if the stringers were indeed bad, and I did nothing and ran the boat the way she is?

The main reason Im asking is because I would love to run the boat as-is for a few years before I start any surgery on her.

Any input/advice welcome
Thanks, Scott

[RickK]

I knew something was wrong on my 170 as I was cruising in choppy water and could see the bow twisting.  When I replaced the sole I found that the starboard stringer (may be a coincidence it was the way the twist was going - clockwise) was shattered toward the bow of the boat.  I repaired that and it's rock solid now.

Waterlogged foam will make the boat sit lower in the water.

Look for these things when you check the boat out on the trial run.  If you can't water test it - all you can do is hope I guess.

[LilRichard]

I would look for strange stress cracking in the hull bottom.  You will see obvious signs if the stringers are badly separated, because the hull will be flexing enough to crack the gelcoat (most times, not always).  Look for cracks all running in the same direction - not impact cracks.  In addition you may see what Rickk is referring to - hull twisting.

Otherwise, you will need to dig into the boat to understand how bad it is.

Running a hull with broken stringers could result in catastrophic hull failure.  FRP hulls are only meant to flex a certain amount as the stringers provide the bulk of the support.  With a completely broken stringer (in theory) one could crack a hull in half.

[Mad Dog]

Does this year model have trapazoid stringers or beam type?  If the latter, there is a high probability the stringers are rotted and not easily verified.  If the former the foam fill is probably saturated.  Like Richard said it will be heavy and sitting low in the water.

MD