Having an accurate measuring device on board not only verifies the size of your catch, but also helps ensure that fish you retain meet state and federal size limits. Many state natural-resource agencies offer free fish-ruler decals, which can be applied along an inwale, on the deck or atop a gunwale. Many tackle stores sell such vinyl decals as well. Another style — and one of the coolest we’ve seen — is the SeaDek 36-inch fish ruler, available in closed-cell EVA foam in thicknesses of 3 mm ($25.95) and 6 mm ($42.95), each with adhesive backing. The 3 mm ruler comes in four colors: Bimini blue, olive green, storm gray and mocha. The 6 mm version is available only in storm gray over black.