I have been out in the Seahorse yard inspecting keels. I hope you find my description of keel building to be informative and useful. The DD462 has a box keel, which is to say that it is formed like a box, in that it is hollow and there are sides, top and bottom. The components are all steel of at least 1/4 inch thickness. The keel is about 4 inches wide at the bottom and tapers outwards until it attaches to the hull. At the top the width is about 6 to 8 inches. The height is about 16 inches at the narrowest and about 3 feet near the shaft log. There are internal dividers every couple of feet, they have holes for lightening purposes of about 2 or 3 inches in diameter. I do not believe anything is placed inside before closing up and this would create some slight amount of buoyancy. About 10 feet from the bow the keel line changes angle about 30 degrees or so and tapers into the stem. This box arrangement should be quite strong and resist any groundings that might occur over the life of the boat. In the event that the keel were damaged it would most likely crumple and would not damage the hull proper, which would simplify repairs considerably. It would appear that the deepest part of the keel when submerged is right near the rudder post. There are five hulls in various stages of construction. The shaft log is wrapped with an extra reinforcing strap about 9 inches wide and extending back into the keel about a foot. The steel log has an inner shaft of fiberglass which itself is about 1/2 inch thick. There is no hull with shaft installed, so I can't describe that. Regards, Mike Capt. Mike Maurice Tualatin(Portland), Oregon.