The floors should reach from the keel to three or four inches above the load water-line ; and the timbers from the gunwale down the sides of the floors to within eight or nine inches of the keel.
The transom will be liin. thick, fitted at the back of the sternpost, as shown in the Sheer Plan.
The rudder will be shaped as shown by the diagram B (under the Body Plan, Fig. 65). Pintles will be dispensed with, and instead gudgeons and braces used, through which a brass rod will pass. This arrangement is necessary, as the rudder will hang considerably below the keel. If the braces are fitted over the gudgeons on the sternpost and a transom at g h (Sheer Plan), the rudder will lift on the rod if the boat drags on the ground, and will not unship.
The rabbet in the stem will be cut at about tin. from the inner edges of the stem piece as shown by the ticked line v in the Sheer Plan. The rabbet in the keel (being a continuation of the rabbet in the stem) should be cut not less than one inch from the upper edge ; and the same from the upper edge of the dead wood aft, and be deep enough to take a good fastening.
The boat will take about 4cwt. of ballast with three hands on board ; this ballast should either be in the form of shot bags, or flat bricks of lead cast to rest on the top of the floors, but sunk between them. These bricks would be under the platform or bottom board, which should be securely fastened, but at the same time be readily movable. If there is no objection to a cast-iron platform, the " bottom boards " can be dispensed with, and a thin iron slab cast to fit over the floors on either side of the centre plate. For such a boat as the design given the slabs would be 6ft. long by lft. 6in. broad, and 1 iin. thick near the keel and lin. nearest the bilge. They would be cast with grooves to fit the floors, and the grooves would gradually deepen from nothing at the bilge to 4in. depth at the keel side. In the stern the usual bottom board or " stern sheet " would be fitted ; and forward either a board or a grating would be similarly fitted.
Of course, no plan of lead or iron ballasting will make such a shallow boat as the centre-board gig stiff, in the ordinary meaning of the word, and the large sails (plans of which will be given hereafter, with diagrams of other boats) should not be set unless two or three hands are on board to sit to windward.
The plate or board has been made rather smaller than is usual ; but it has been found that a very large board, whilst it adds largely to frictional resistance, does not add proportionately to weatherliness. A very small piece of board will check the leeway tendency of a well-shaped and fast boat, and no doubt quite enough has been shown in the design.
A belief sometimes exists that a centre-board adds to the stability of a boat : so it does if made of iron or other metal, just the same as an iron or other metal keel would ; but if the material be wood not heavier than water, the tendency of the board would be the boat, as the wood would strive to come to the surface, or, in other words, to float : thus, the larger a wood board were made, and the deeper it were lowered, the more urgent would be its tendency to assist in upsetting a boat. A board, however, causes the process of heeling to be a little more slowly performed, as the board has to be moved through water, and the resistance to the board being so moved is of the same nature as the resistance of the water to any plane moved in it. Thus, when a boat is once permanently heeled, or has settled down on "her bearings," as it is termed, the board will be of no more use for stability, as its tendency will be to float or come to the surface. If the boat is struck by a squall which only lasts, say, four or five seconds, the board may possibly prevent an upset that otherwise would take place; but if the squall continues, and is of a strength to upset the boat without the board, the boat will be assuredly upset with the board only it may take two or three seconds longer to do so.
The question of decking is one which will naturally arise in selecting a boat. No doubt a locker of some sort, to stow cushions, gear, and sails in, is a desideratum in a boat ; but a deck forward and aft, with waterways amidships, as shown in a sketch given farther on, must increase the weight, and for up-river sailing are quite unnecessary. However, if the boat-sailer is equal to the " stress and the strain of wind and the reeling main," and can confidently knock about in the Sea Reach, he will find the decks and water ways a great comfort. They will keep out all the water likely to lop on board, and nothing worse than spray need ever get into the well amidships. A partly decked boat with waterways, built by Messenger, of similar dimensions to the one we have given a design for (Plate III.), but fuller forward and aft, made a trip to Margate and back last autumn; and, whilst she behaved just as she ought in a breeze with some sea, she was not too heavy to row if occasion arose. However, trips to Margate from the Thames, or from Southampton to Portland, are not quite the work for centre-board gigs, and boats much better adapted for the purpose can be built.