Starting to let the hog drop
The shipwrights are starting to let the hog in the MORGAN to drop by natural gravity force. (Hogging is the tendency of vessels to sag at the stem and stern ends due to the less buoyant nature of these parts of the vessel as compared to the amidships. Hogging is manifested by the curved shape of the keel.) The process is complicated. Selected keel blocks are configured to have a softwood “crush” block between the hardwood blocks and the bottom of the false keel. As the hull drops, the softwood crush blocks are pinched and are removed with a chainsaw. This process will be repeated several times until approximately ½ of the MORGAN’s 9 5/8s inch hog is eliminated. Further evidence of movement is the need to back off on the screw jacks at the stanchions. This is necessary to ensure equal distribution of weight on the hull supports.
There are several keyholes which have been revealed in the false keel. (The false keel is the bottom most portion of the keel. It is relatively new whereas the full keel to which the frames are attached is original construction.) The key holes permit the scarf fabrication of the false keel to expand lengthwise. (There is a good depiction of scarf fabrication in the THAMES keel exhibit.) Meanwhile, as the keel is lengthening, the main deck is being forced to shorten. The shipwrights will “reef” out some of the butt joints in the main deck to enable this.
The longitudinal strength of the MORGAN’s hull is compromised by rotten planking and the poor condition of the ceiling. Both the planking and the ceiling (which is original to the vessel), are critical to the vessel’s strength. The natural stresses in the hull must be balanced slowly and as the desired hull form takes shape, the shipwrights will replace key planking and the ceiling. It’s a three year process and a complicated feat of workmanship.
The shipwrights have a varied selection of fasteners that they will work with, ranging from a wooden trunnel (short for tree nail) to a metal rod to various sizes and materials of metal “spikes.” Each is used for a specific purpose. For instance, planks are fastened initially with metal “butt spikes” which secure the planks ends to the framing to lock in the shape of the bend. Metal hanging spikes hang the plank in place. Finally trunnels are driven (paired with a hanging spike) to secure the plank to the frame. The trunnel has a club like shape and is allowed to dry thoroughly. When installed, one end is split and wedged. This end is driven to the bottom of a predrilled hole. The driving end is cut flush with the plank and also wedged. When the vessel becomes wet, the trunnel expands creating a very tight fit thus enhancing the strength of the hull.
An exhibit showing the various types of fasteners will be prepared for the Shipyard Gallery. The type of material used in metal fasteners is very important. Bronze or copper resists corrosion, whereas steel deteriorates quite quickly. The type of metal used often determines the life of the vessel. Older oyster skiffs in the Chesapeake have survived well past their newer sisters, because non-steel fasteners were used in their construction.