CENTRE-BOARDS.
The foot steering gear requires the centre-board case to be sufficiently low at the locality of the foot yoke—i. e., aft. 9in. forward of the man's back—to allow the foot yoke to swing at eight inches above the foot boards. This, combined with reducing fore-and-aft weight, has suggested the form of centre-plate shown in Plate =VII. The centre-board case is thus fitted to the keel (see Fig. 122, page 412). The sides of the case are rabbetted into the keel as shown, and fastened by screws which go clean through the keel, the ends being subsequently filed down in the slot.
The centre-board should be made of sin. iron " boiler plate," and should be galvanised; the measurement should be taken from the drawing, and laid off full size on paper; the paper mould, having the pin hole and chain hole marked on it, should be sent to the foundry, and great care should be taken in seeing that the plate is perfectly straight. Cast iron centre-boards are often used, but they are bad, in that sudden breakage is the common result of a hard lateral bump on the ground, and also that, to obtain the same weight as " boiler plate," a thicker plate must be carried.
On the position, forms, and areas of the centre-board or boards and rudder depends, to a very great extent, the successful sailing (apart from actual speed) of the canoe. As, has been already pointed out, the position of the centre-board is determined by the requirements of space for the man and the stepping of the masts ; two or three canoes, noted for their sailing qualities, have been ingeniously fitted with " fan " centre-boards, which collapse into a case which does not come above the floor boards. Such centre boards can, of course, be placed regardless of the well seat and steering gear; and, provided they are of a pattern and make which gives sufficient rigidity when in the sailing position, they are undoubtedly of service.
But the position of the sails in a canoe does not admit of much variation. Leaving out of the question extraordinary rigs, the centre of effort of the mainsail-and-mizen rig (which is the most popular in canoes) will be generally found to be at the mid-length, or not more than eight inches abaft it; then, the canoe being of shallow draught, the rudder, to be effective, has to be somewhat large in area, and, being at the extreme end of the vessel, naturally carries the centre of lateral resistance considerably aft; then, to bring the centre of lateral resist ance forward and near to the vertical of the centre of effort of the sails, the centre-board has to be placed slightly forward of midships ; therefore, it is evident that the position and area of the centre-board is of the first importance, and its mechanism merely a matter of convenience.
Two square feet area of centre-board has in practice been found amply sufficient, even in match sailing ; and whether this area be given in one large plate or two small ones is practically immaterial as far as lateral resistance is concerned, but in relation to turning and manceuvring there is a great deal to be said on both sides. In the first place, the
single board and the double board are equally efficient in counteracting leeway, that the single board is the more delicate and perfect for eating to windward ; and the double is more perfect than the single for reaching and running, and is undoubtedly the more powerful weapon for manceuvring when skilfully handled. With the single board the canoe on a wind will answer the least touch of her helm or alteration of her sheets; and, except for shoal water, the board need not be touched from start to finish. It is often asserted that a single centre-board (of course in relation to other centre-boards) is not so good for beating in rough water, for the reason that her head is easily knocked off the wind by every sea ; but it should be remembered that a boat does not eat to windward by virtue of gripe or forefoot ; she works on her common centre of lateral resistance, and, though the bow may be knocked off the wind by the seas, a like facility of movement exists for bringing her to, and, further, the single-plate boat is able to take advantage of smooths or free puffs for getting a screw up and a rapid fill away again. It is the crest of the wave that will knock the bow off the wind, but this is almost an advantage, and it places the vessel in the best position—" three corner ways on "—for dropping gently down the back of the sea, of the wind, and, consequently, "all full," and gathering way for a neat luff up the face of the next sea. (See page 18.) No doubt the double centre-boarder, in the hands of a skilful canoeist, has many advantages over the single-plate craft ; but, to utilise these advantages to their full, a judgment and quickness are needed, which can only be obtained by long and constant practice. The experienced hand in a double centre-boarder will use his boards, by alternate lifting and dropping, when on a wind or reaching, almost in preference to his rudder; in fact, the working of the boards will be attended to before working the sheets. The ease with which the centre of lateral resistance can be thus shifted forward or aft of the centre of effort of the sails places within his grasp a power of turning which in match sailing is of the first importance. If from any accident the mizen is lost or has to be stowed, the canoe will be handy under mainsail if the after board be hauled up ; and if caught in a squall, the mainsail can be stowed and the canoe hove to under mizen and fore centre board— the aft one being of course hauled up. Without going into details of intricate manoeuvres, it may be stated that when the canoe is sailing, say, close-hauled, if the afterboard be suddenly hauled up, the craft will fly up into the wind's eye. Of course this can be augmented by easing the fore sheet, and also by putting the helm down—i.e., bringing the rudder to wind ward. In like manner, for quick bearing away, the after-board would be kept down, the fore-board lifted, the mizen-sheet eased off, and the helm put up.