Sorry guys, Cap'n Tolley's will do nothing for those cracks. The creeping crack cure is actually water based and intended for wood. It won't even penetrate fiberglass and only sticks lightly to it. The cracks in the pictures are know as 'crazing' most commonly and are caused by a number of factors. As Jim mentioned age and stress are two of them, UV plays a role as well. Stress in high flex areas is most common, even in new boats. Fiberglass does flex, one of the best characteristics of the material is flexing rather than cracking... But the gelcoat over it is much harder and therefore a more brittle substrate, so if the fiberglass underneath it flexes more than the gelcoat can handle it will it crack. Age and UV exposure can accelerate this. Cool nights and rapid warming in the tropical sun takes its toll. Notice how the big crack appears near the 60 degree incline from the deck to the cabin? Hard turns like this, especially 90's, are where they are common. You'll also find them around areas where hardware is mounted; cleats, chainplates, etc.
The best repair is to grind the crack all the way to the fiberglass with an engraving bit on a dremel tool, then fill the crack with polyester gelcoat paste that is color matched. Spectrum Color sells 2oz jars for $25 that is color matched to most major brands. Two oz will fill many, many feet of cracks. Even a sloppy application is easy to make pretty by sanding and wet sanding then buffing, very user friendly.
For the non-skid, its more of a pain. To fit it correctly you have to buy the female mold pattern that matches your non-skid, Flex-o-mold I believe is the trade name. Its like $50 for a sheet and more of a pain than its worth. I think most people are better off grinding and filling cracks in the white smooth areas of the boat, and then sand the nonskid down and roll on Kiwi Grip.
