I'm new to the forum but have done a fair amount of reading here. I haven't been able to find a clear answer to the following question: how much flex in an old (1979) Nacra 5.2 hull is OK?

I'm parting out my old Prindle 16 due to excessive hull delamination and am shopping for a Nacra 5.2, but I'm wary about hull condition. The one I looked at today (from 1979) seemed fairly sound (according to advice gleaned from this forum) but I'm concerned about flexing in the hulls. Specifically, the longitudinal stringers along the inside of each hull surface have no flex---all seem rock solid. However, the skin between the stringers can be pushed in a bit with firm pressure (which doesn't surprise me much) but in almost all areas the pressure causes a crackling sound. There are a few areas where the flexing is somewhat less. I noticed that on a nearby newer Nacra 5.8 the flexing didn't cause any sound at all.

How concerned should I be about this cracking sound? I assume that the fiberglass resin is old and brittle and is cracking when flexed. Should I run away or is this a normal, minor issue on an old boat?

Thanks in advance for any advice from those who've been there and done that.

For what it's worth, the boat comes with a rusty but strong trailer, a fairly crisp main, an old jib, two trapezes and harnesses, good rudders, OK daggers (one with a big bite out of the front corner), new tramp, probably original rigging, original Harken blocks, and a crappy repair of a 10" crack inside one dagger trunk. No other obvious structural issues. $1450 in Minneapolis.

My '76 5.2 did the same thing. Without a core lamination it will flex more but that is fine. If the stringers are solid than they have not been damaged. Price is at the top end with how you described it but it is at the beginning of the season. The chunk missing on the dagger and repair of trunk worry me. $900 would be my max.

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David
Nacra 5.5SL
Nacra 5.2 (sold)
San Diego, CA
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peteraj

However, the skin between the stringers can be pushed in a bit with firm pressure (which doesn't surprise me much) but in almost all areas the pressure causes a crackling sound.

How concerned should I be about this cracking sound?

A cracking sound never indicates something good. The resin is breaking down or the bond between the flange of the stringer and the inside of the hull is letting go. Personally, I would keep searching for a different boat.

sm

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crappy repair of a 10" crack inside one dagger trunk.

That alone is a good reason to RUN. That trunk may leak like a sieve, & they can be hard to fix due to access.
These vintage Nacras are solid glass, it is normal to get some flexing,(oilcanning) on the sides,(the tops should be solid everywhere), but it shouldn't crunch. The stringers may be delaminated from the hull, that causes the noise when you push on it.
Combine this potentially very serious problem, along with banged dagger, old jib, original rigging...this is a $500 boat. you will put a lot of money into it. There are far better, newer nacras.
A big bite from the front of a dagger,(especially combined with a trunk repair), most likely means the boat was run aground, hard. the fix can be a b*tch, with a capital B.
Don't waste your time, I bought a really nice 5.0 for less money than that, & it's an '88.

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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Thank you all so much for your thoughtful and very helpful replies! I will keep looking for a boat whose price more closely fits its condition and has fewer red flags. I really appreciate you all taking the time to reply. Peter