Hi Paul...  Due to getting old epoxy, I had to remove ALL the fiberglass on the deck of my Wood Duck 12.  In doing so, I DID sand thru the top layer in two areas of the sheer deck AND a few areas at the hull-to-sheer connection.  I got 3/8" wide iron on wood trim to resolve the sheer area and made my own "decal" to hide the sand thru.  I'm suggesting yyou might think about applying a home created decal/overlay to the areas of the crack.  Of course, you will need to apply it to BOTH sides to "balance" the looks.

A woman who contributed on this site, named Kathy, gave me the idea.  I found an approiate design, in my case, I found a head shot of DAFFY DUCK, my kayak's name, on the computer, transfered it via copier to rice paper and presto, a decorative blemish hider!!!! (THANK YOU, Kathy, whom ever you are...).  You could go with a random design or a cartoon as I did.   If I can figure out how to post photos, I'll do so, but do NOT hold your breath.  My address is Tugbruce and my server is G.....mail.  If you send me an email, I CAN port to those!!!   Good luck....   ~BRUCE~

As Bruce suggested, the simplest "cover up" is some decorative art added to the location.  Probably more difficult to do at the coaming and surrounding areas, though.  A veneer "inlay" added to the surface of the wood, under the glass layer, would be a possible cover up too.  You could do one on each side to make it less obvious as a "fix" but it will still be difficult at the coaming, I suspect.

FrankP

The hull to deck joint is the weakest link in a boat and the highest stress is the middle third.  This is proven in Finite Elemental Analysis of ships, sailboats & also applies to kayaks.  This part of the deck & hull is subject to both tension and compression and the primary reason a good shear clamp and glassing of the joint is good boat building practice.  If you ever see a damaged boat from waves/overloading or crushed in surf, more than likely more damage will be in the middle of the deck/hull.  Remember when the Americ's Cup boat from Australia broke in half in San Diego?  Stars & Stripes in NZ?  Both broke from wave compression combined with winch and rigging loads.  Kayaks and small boats are no different.

If you are only using your kayak in calm waters w/ no load...no wave, etc., it may never fail, but if you load it up glassing  the shear under the deck is better than trying to repair it after it has cracked or separated in a seaway or from over-stressing it in a tie-down or high wind situation on the highway.

I recently finished a Shearwater 17 Hybrid for an auction and put extra glass around the shear near the cockpit, glassed the joint inside, and placed carbon fiber across (side to side) the underside of the deck in strips fore & aft of the cockpit & around the border of the cockpit. Almost no weight was added, but it was stiff and very firm with full weight on exit sitting on the aft deck in front of the hatch.  Yacht design analysis shows the middle third of a boat's hull to deck joint is the most vulnerable to damage from load..waves, weight, cargo, paddler...get the picture.  This part of the hull & deck goes through both compression and tension stresses.

A good practice would be to glass the inside of the shear clamp as far forward and aft just beyond the hatches.  Any further is not needed as long as your glue joint was good.  Besides, when you pack the boat w/ gear, these areas further forward or aft of the hatch opening are impossible to sand smooth will catch/snag on gear bags.

Dirk