Let’s take a moment to consider what, exactly, was meant in point 3 above:
3. The requirement to identify the shape and form of a ship which provides suitable sailing and handling qualities in all conditions, and to handle the intended sails well.
Many treatisers and mariners from the time provided their own description of what these qualities were. Let’s take a quick look at a few:
A ship, whether destined for war or commerce, ought to be able to bear a certain determined lading, and be sufficiently capacious to afford ample accommodations for her crew, with all the contingencies involved in the consideration of their health and comfort. She must carry the cargo with ease to herself; the artillery in a perfectly efficient state, whether space for working the guns, or the height of those guns above the surface of the sea, be considered. She must be so formed that she shall be able to make her passages with velocity when the wind is favourable, and contend with it advantageously when it is unfavourable.
The ship must be capable of being worked with ease, rapidity, and certainty, however adverse the circumstances may be under which the maneuvers are performed; for it will sometimes happen, that the more unfavourable the circumstances are, the more imperative is this necessity for success. She must have great stability, or the power of resisting inclination, and of restoring herself to an upright position when inclined; and this must be so nicely graduated and adjusted, that the perfect safety of the vessel may be insured without any injurious strain being brought upon the masts or rigging by an excess of this resisting power. She must be able to sail over rough seas without any injury from the pitching or rolling motions which will ensue, and without the hazards to the crew, to the vessel, or to the cargo, which would result from a tendency to ship seas when thus situated. Her masts must be so proportioned that they shall be sufficiently strong, taking into consideration the support they derive from the rigging, to resist the strains to which they will be subjected, and that without being so heavy as to diminish unnecessarily the stability of the ship, or require superfluous lading from extra ballast. The masts must be lofty enough to spread an adequate surface of canvass to furnish the propelling power, and, at the same time, be so placed and so proportioned to each other, that this propelling power may be readily converted into a series of mutually counteracting or co-operating forces to insure quickness of maneuvering.1
Let’s jump forward about 30 years to 1829:
Disregarding the fundamental principals of floating bodies, and too hastily giving up as hopeless the attainment of a theory combining experience with established scientific principle, they have contented themselves with ingeniously inventing mechanical methods of forming the designs of ships bodies, which they did not even pretend to prove had any conexion with the properties of the machine, necessary to ensure the qualities conducive to its intended use. For instance, - some invented methods of forming ships' bodies of arcs of circles; others of arcs of ellipses, parabolas, or of whatever curve they might arbitrarily assume. Taking anyone of these curves as the principle of their design, they investigated, with mathematical accuracy, the means of completing the form of the ship's body in correct accordance with their assumption. They did not attempt to show that these curves possessed any property which would render a ship a faster sailer, a more weatherly, or a safer ship than any other curves which might have been adopted in the construction of the ship's body.2
There are many others with similar statements. What was desired for a ship was that it:
1. Handled the intended sails well (that is, was stable and responsive)
2. Must carry the cargo (or weapons &.c.) intended at the correct draught of water.
3. Should sail well at all points of the wind.
4. Should be a fast sailer.
Each of these qualities brings a specific set of design criterion, often at odds with each other. Designing a stable vessel by increasing breadth often decreases the speed. Increased ability to sail to windward may reduce the ability to carry the intended cargo at the desired draught. Trial and error design approaches brought the ship near to a desired condition, but as often as not a success in one aspect resulted in a poor result in another. What Morgan & Crueze (and, indeed, many others during the later 18th and 19th centuries) were trying to accomplish was to apply a mathematical solution to the design of a ship to achieve the best compromise between the competing design requirements.
1. Society for the improvement of naval architecture London. 1792. Some Account of the Institution, Plan, and Present State, of the Society for the Improvement of Naval Architecture: With the Premiums Offered by the Society, List of Members, and the Rules and Orders of the Society. To Which Are Annexed Some Papers on Subjects of Naval Architecture Received by the Committee. http://archive.org/d...nst00unkngoog. Page 5 (43 of 128)
2. William Morgan and Augustin Francis Bullock Creuze, Papers on Naval Architecture and Other Subjects Connected with Naval Science Vol. II, vol. II (G.B. Whittaker, 1829), page 3.