My '64 Glastron Skiflite 142 has a few cracks in the deck gelcoat which I believe are mostly from age shrinkage. What is the best filler to use in these thin cracks? I need something thin enough to flow or push in (putty knife?). I'm thinking about then repainting the boat once the cracks are filled. This is of course after I split the hull and rebuild the rotting transom. <br /><br />Lake of the Woods - Walleye country