What makes Sciarrelli designed boats stand out?

Carlo Sciarrelli designed yachts known for being balanced, easy on the helm and fast. As William Fife used to say, “A yacht of beautiful and sleek lines will invariably also be fast as well”. Carlo Sciarrelli embraced this principle.

Many years ago during my search for a suitable boat to buy, a proud owner of a Sciarrelli that was up for sale, showed me the original brief he sent to engage Carlo to design his boat. He specified that he wanted a beautiful, fast and safe yacht. I am not sure that anyone would specify to a naval architect anything different, such as perhaps an awful, slow and unsafe boat; the fact to the matter is though, with Carlo Sciarrelli you were reasonably sure to get something very close to the ideal implementation of the first specifications, while with other less gifted designers, examples of yachts that ended up fulfilling at least partially the latter description are unfortunately numerous.

Sciarrelli explained the way he designed hulls during the lectio magistralis he held during the ceremony for his honorary naval architecture degree. All Carlo Sciarrelli designed hulls adhere to one principle and its simplicity is as striking as its effectiveness.

In general, all hulls are combinations of the two ways of tapering a boxy form into something that will present the least possible resistance to advancement in water. As shown in the picture below, this is true for both archetypes, the so called “plank on edge” (deeper and narrow hulls like those of English cutters) and the so called “skimming dish” (shallow and wider hulls like those of American sloops).

Starting with the un-tapered shape we can see, as shown on the right side of the picture with the skimming dish, either by tapering vertically or horizontally, or better, with a combination of both: vertical for the fore part of the hull and horizontal for the aft (shown in the picture for both hull types). The bodylines of these very simplified forms will be vertical in the fore part up to approximately midship and horizontal in the aft part.

Principles of hull design

In actual hulls, in order to get a smoother transition from vertical to horizontal tapering, the lines will gradually rotate from vertical to horizontal as shown in the two examples in the figure below. Irrespective of whether the hull is deep and narrow or wide and shallow, it will present a point of convergence of the lines of the forepart at the bottom while the lines in the aft part will converge to a point on the side. The only difference between a cutter and a sloop will be the distance from and the angle with the axis.

Bodylines of a cutter (left) and a sloop (right)

Carlo Sciarrelli’s intuition was to eliminate completely the need of transitioning from a vertical to a horizontal tapering, by moving the convergence points to the infinite and dealing only with the angle to discriminate between the various type of hulls. In this way, all the lines, instead of fanning from two distinct points, remain parallel. The principle is shown in the picture below. This provided for very well balanced hulls, easy on the helm and seaworthy, which resulted in regatta winning yachts.

Principle used by Carlo Sciarrelli

Sciarrelli kept this principle unadvertised until his lectio magistralis. According to him, at beginning of his career he was concerned that prospect clients will be suspicious of a young and not yet established designer trying something new and unconventional. The excellent results his yachts were obtaining in regattas were his best and only advertisement.

One must think though, that even if this principle was not advertised, it was probably not a secret. Perhaps Carlo’s clients did not notice this peculiarity on the plans, but for sure shipwrights must have wondered why planking a hull designed by Sciarrelli was so much easier, given the fact that planks did not have to be twisted as much as in all other boats. The minimal twist provides also for stronger and stiffer hulls. This particular shape of a “constant V” running from bow to stern and can be easily recognized when a Sciarrelli is on the hard. This is what makes them stand out. Hence, besides being beautiful, safe and fast, Sciarrelli’s designs were not difficult to built. What is more to be desired in a yacht?

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