Floor Timbers

The glossary will say something like this: "Floor timber-an athwartships member, usually of wood, used to tie the heels of the frames to the keel." This definition comes close to being the ultimate in oversimplification. The floor timbers provide a base for the engine bed, intermediate shaft bearings, and a mast step. They tie the two halves of the boat together down where it really counts. They take in hand the enormous wringing strains of the ballast keel, and transfer these loads smoothly and subtly to the main fabric of the hull. They connect a flexible keel to the longitudinal rigidity of the topsides. They even provide support for a platform to walk on. Unfortunately, they are not always provided in sufficient numbers, styles, and sizes to do this work in a satisfactory manner. Various types of floors I can think of seven different forms in which this member can appear, each one with certain virtues of its own (Figure 8-1 ). There's the simple plank-on-edge, suggested by the above definition, which can go before, abaft of, on top of, or between the frames. In its best form this simple floor is shaped from a "grown crook," with long arms up the inside of the planking. You are most likely to find it in a primitive boatyard where the builders live close to the forest and time is not of the essence-and you can well envy them their pile of sweeps and knees, because we can't improve on them a bit with all our refined techniques. There's the metal floor-forged from wrought iron or steel, or cast in bronze, or welded in web form from bar and angle stock. This usually is used up forward, where an honest plank floor would stand too high and spoil the headroom. It's a pretty thing, and very expensive; but it sometimes fails to do its job. I'll have more to say about this later. (Once upon a time, there was a special rating rule in the Great Lakes which for some reason penalized inside ballast, as distinct from structural members. One boat appeared with a 600-pound bronze fairing piece on the lower end of the rudder stock; another used, in the refrigeration system, bronze tubing with a 2-inch-thick wall. Needless to say, the designers of these boats went wild with metal floors. In my innocence I contracted for and built one of them, and the old scars act up when I think of it. I have suffered since from the failings of three others that came here in mid-career and drooped their chins, as it were, on my doorstep, asking to be made whole again-and I learned a lot about floors from them.) And there's the spring-leaf floor (Figure 8-2), built up of glued laminations, saturated and sealed with super-epoxy, light, stiff, strong, and guaranteed not to delaminate as long as the moisture content stays the same. It is also frightfully expensive, but worth every nickel if you are building a three-ply featherweight to the quarter-ton rule. Such a boat is outside my experience and beyond my desire. However, if my boat won't get there the same day, it'll make it the same summer, fortified by massive, heavy, perhaps crude floors that'll never let a garboard swing open. Let's contemplate some of the stresses that occur in a sailboat with outside ballast. We'll stand the boat on edge and