CHAPTER  2

 

What is a Cruising Yacht?

By Peter Schmitt, CSY Chief Designer

 

 (Author’s comment: lf there is a more confusing area of misinformation in the sailing field than the advantages and disadvantages of light displacement versus heavy displacement yachts; of the racer versus the  cruiser versus the cruiser-racer; well, we don't know what it is.  We asked our designer, Peter Schmitt, to try, in his own words, to define what a cruising yacht is and what it is not. We think you will find his discussion thought-provoking and enlightening—we did, so we printed it here!)

It’s easy to design a fast boat, it's easy to design an attractive boat, and it's easy to design a roomy boat ... but to design a fast, attractive, roomy boat is another matter altogether, and that to me is what good cruising boat design is all about.

There is no excuse whatsoever for a cruising sailboat that is not performance-oriented and therefore, having boat speed on all points of sail, stability, and maneuverability, which are all of the primary importance.  These components of performance will only result from a well-designed underbody consisting of the canoe body and the keel and rudder appendages.  The canoe body must have the necessary volume to provide the best accommodations possible and support at a predetermined flotation line the entire weight of the vessel, yet ... at the same time, the lines of the canoe body must be as sweet and fair as possible to give the minimum amount of resistance to the water flowing past the hull.

The keel and rudder are the appendages that contribute the most to windward performance.  The keel must have enough internal volume to contain the necessary ballast for self-righting stability at all angles of heel for the chosen draft.  Its fore and aft location is extremely important to the steering qualities of the vessel and its shape must provide a highly efficient, aerodynamic lifting surface to resist the side forces of the sails.

In addition to its function of being able to provide complete steering control in any type of sea condition, the rudder should also act as a hydrofoil providing side force lift.  It is my own belief, that a balanced rudder, attached to a full span skeg of adequate size, located as far aft on the underbody as possible, provides the optimum steering control for a cruising boat.  It is a known fact that a rudder with a skeg will be more efficient at higher degrees of rudder angle than a rudder without a skeg.  Positioning the skeg well aft contributes to a more efficient lateral plane, thus making a better tracking vessel.  In addition, the use of a skeg allows the placement of a heavy, cast bronze gudgeon at the lower end of the skeg to support the rudder stock.  This places the stress on the rudder stock in the form of torsion only, and not torsion and bending as it is when a rudder without a skeg is used.

Another appendage of the underbody that is not found in many cruising boats, but is used on all of CSY's boats is what I call the propeller skeg.  This skeg is molded integral with the hull shell and contains the stern tube and propeller shaft bearing.  Its primary function is to act as a shroud to protect the lower propeller blade tips from debris.  An additional function is that it is a much stronger method of captivating the propeller shaft and stern bearing. Whereas the normally used bronze strut can loosen in time from shaft vibration and is subject to damage, the solid rigid structure of the molded skeg can never fail.

Perhaps the word heard most often during the design of a boat is the word compromise!  And compromise we must!  There are so many compromises made to a boat when it is on the drawing board that it is impossible to keep track of them.  There are, however, three specific areas of a vessel that can never be compromised, as far as I'm concerned.  These are the hull structure; the rig and rigging; and the steering system.

A failure of the auxiliary engine or the electrical system is an inconvenience to be sure, but the vessel is still intact and seaworthy.  But ... to have a failure of the hull structure, the rig, or the steering system - an occurrence which will most likely take place in heavy weather conditions - will place the vessel in immediate jeopardy.

Fiberglass construction is a wonderful material for building a boat. The basic fibers which make up the glass fabric are among the strongest structural elements known to man.  No other boat construction material gives us the freedom of design, the added interior volume due to the lack of frames, or the rot-free, worm proof, easily-maintained hull shell.

I suspect that when most people buy a fiberglass sailboat, they take it for granted that the hull laminate is carefully and painstakingly laid up and that the hull laminate is of adequate thickness to provide water-tight integrity under the most adverse conditions.  Unfortunately this is not always the case.  Each builder buys his resin and glass by the pound and it is one of the few areas in fiberglass boat construction where he can skimp on materials and labor, save money, and hide it from a buyer.  No matter how it is constructed, in actual sailing conditions each boat must endure the same repetitive cycles of heavy stresses, the magnitude of which increases exponentially with the size of the vessel.