Gerald was here this weekend, and will be for the next as well, so the boat-shed was a very busy place. With all the futtocks in place, the next task is to put in the deck beams that run overhead. I was surprised to learn that these do not sit on top of the futtocks. A moments thought would make this clear, as the futtocks extend beyond where the deck starts, up to the level of the side railing, or around waist height for someone walking on deck.
Instead of attaching to the futtocks, the deck beams will rest on thick planks (about 2-3 inches thick and more than a foot wide) that run horizontally along the futtocks. These planks are called deck shelves. Dovetail joints will be used to allow the deck beams to lock into the deck shelves. Currently gravity working on the futtocks and planking already in place exerts a pull that tends to make the futtocks spread outwards and downwards away from the center line of the ship. The dovetails in the deck beams and deck shelves prevent the futtocks from spreading outwards and make the structure of the ship much stronger.
While the ship looks imposing and substantial as it rises from its keel resting on blocks, in reality is is very fragile, and will be until it is completed and in the water. The whole structure is designed to resist the inwards compressive forces that the water will exert, and is much less able to support its own weight while out of water. Lacking the planking that ties the futtocks together, the whole skeleton of the ship can be twisted along its axis pretty easily, like wringing out a dish-rag.
Hammering on the wrong portions in the wrong rhythm can actually set up an oscillation that could splinter or fracture the futtocks and keel. This is why we often have to “back up” the far side of the part being pounded on with a heavy weight to minimize the shock transmitted through the fabric of the ship. The addition of the deck shelves and deck beams will reduce this risk a lot. The planking and deck planks will serve as horizontal stiffeners that will help the ship resist the twisting action found in a heavy sea.