cracks in composite kayak

I have a Necky lookshaII that has developed a crack right in front of the seat. I looked on the outside of the hull and can see no crack. Also when I drag a razor blade over the crack it does not catch in it. I have pressed on the outside of the hull while doing this to see if the crack will open up and the razor blade will catch and it still doesn’t. Should I be worried about this. I have paddled it about 50 miles in the last week and it has not spread.I am in the process of selling it on craigslist and I want to make sure I am not selling something that should be repaired first. Thanks in advance for the info. Jaws

Without pixs I can’t be sure
but from what you discribe it sounds like spider web cracks in the gel coat. They are harmless so don’t worry about them.

not a spider web crack
It is perfectly straight about 4inches long. There is a keel ridge that runs along the bottom of the hull and the crack is off to one side.

may not be a crack
could it be a sharp edge of resin left over from vacuum bagging?

Yeah, if you can’t get your blade in it,
even if you pressure the hull from outside, then it doesn’t sound like a true crack.

On the few occasions where I have hammered a composite boat hard enough to cause a crack inside the boat, it has been fairly ragged, and not at all hard to feel just with my fingers.

I wish I could see it. Sounds interesting.

Related to LeeG’s comment about
vacuum bagging…Did the builder possible put a foam or spheretex core in the bottom of the boat to increase stiffness? If so, the “crack” may be a clear line of resin that has filled a joint in the core material.

Hand lay up…no bag used
and typically resin rich in those days. You may have a surface crack in the resin. Is the boat glass, or Kevlar / glass with the typical old Necky carbon bands and spruce keel half round??

These boats were hand laid with a blend of Poly and Vinylester resin.

OK, that helps a lot, but if it is just
a surface crack in the resin, why can’t he “demonstrate” it with the edge of a razor blade?

Jaws , you call it a crack , but then …
… are unable to determine if it is a crack ??

I’m only posting because I am curious also , and awaiting an outcome !!

Maybe put a bright beam light against the surface and look at it from the opposite side . Use a magnifying glass to inlarge what you are seeing .

Dye test , put a water base dye on the suspected crack (perhaps food coloring) , then wipe it off .

If dye remains in the crack , then there you have it , it’s a crack in at least the surface .

Good question?
Perhaps a hairline minor crack or sub crack between the material and surface?

I’d paddle the thing and worry about it if it gets worse. Easy fix even if worst case scenario.

Rub a little dirt on it…
and sell it. Probably never a problem and besides it’s a used boat.

Yeah, if I were nearby, I’d buy it.

Which direction is crack oriented ?
As Salty mentioned, sometimes seen on these era Neckys.

Probably still subsurface in this resin rich area and really nothing to worry about … but still curious which direction crack is.

The crack runs parallel with with the
hull. There is what I call a reinforcing ridge down the middle of the hull. The crack appears just to the right of the ridge right where it looks like the gel coat on this ridge thins out. The reason I am asking about this is that I am trying to sell it and I don’t want anyone who comes to look at it to feel that it is not sea worthy because of this crack. I will try to post some pictures if I can tomorrow.

The ridge is a wooden half round
and there’s a resin rich area to each side. I suspect it’s a hairline crack in the resin secondary to the hull being deflected. Not uncommon with those boats. I think it’s nothing to worry about.

Yeah, my '73 Moore canoe is
reinforced that way, but I am prevented from seeing hidden problems because the inside of the boat is painted grey.

Ditto Salty, Don’t look @ it : )