We are often asked about the difference between one yacht and another. Each hull design has its advantages and advocates. Here, Y.CO sales broker Jonathan Zwaans explains a little of the mystery behind each…
THE MOTOR YACHT
Traditionally, there have been three main types of hull to choose from when building or buying a superyacht:
The hull is supported by buoyancy, literally displacing water, and travels through the water at a limited rate which is defined by the waterline length. The hull can have a traditional rounded bilge, a hard chine or a soft chine (for an explanation of chines, see the diagram below). A displacement hull makes for comfort both at anchor and underway, however top speeds are in the lower end of the scale, between 10 and 16 knots.
As the name implies, the hull is partially supported by buoyancy but also designed to generate some dynamic lift at the bow. Semi displacement yachts can have hard or soft chine hulls. Italians shipyards and designers tend to favour this design, which gives an element of comfort at anchor while allowing faster speeds underway.
With a planing hull, once the yacht starts making way, it generates a positive lift, decreasing the yacht’s draft as speed increases – or, planing. Less wetted surface equals less drag, allowing planing hulls to reach impressive high speeds. Planing hulls typically have several hard chines to achieve a smoother ride. These hulls are more efficient the faster they move through the water, but beware, that increase in energy does result in a higher fuel bill!
I advise anyone buying or building a yacht to choose the hull shape which best suits the way they intend to use it, taking into account where they are most likely to be cruising. Two more elements which will need to be considered are the bow and the stern, which I will cover in future posts.