The bottom of PocketShip's keel is stock lumber covered by one or two layers of fiberglass. That keel gets draged over the centerline bunk whenever loaded on/off its trailer. And if grounded and/or beached, she may be scraped against who knows what. I wanted some protection.
So, for Tattoo, I installed a "shoe" of 3/4" SS half-oval on the keel from the noseblock to the stern (skipping the centerboard). At the leading edge of each of the two pieces, I cut a shallow (1/8" sloping) groove so that the leading edge (of the half-oval) couldn't snag on anything passing under the keel. The first inch of the leading edge of each half-oval piece was bent and tucked into the groove. She was bedded carefully with compound and screwed in place. Flat-head screws had a better profile than oval-head screws. Even so, they needed filing to keep the edges under the half-oval profile. It adds a little weight, but in the right place (down low).