Motor ships with size from 12,5 meters and more are named motor yachts through habit. In fact these are the same cruisers. Unlike the sailing yachts of the same size, motor yachts make long ocean voyages rarely. The main reason is impossibility to place plenty of fuel on board. Therefore to cross the Atlantic ocean on a 20-meter motor yacht is not a small achievement. There`s another reason: an average motor yacht is not so navigable, as good sailing yacht with a deep-seated heavy ballast keel and relatively low superstructure - such yacht can survive after complete capsize.

Good motor boats and yachts can handle hard sailing conditions. But their construction must provide exceptional stability, so that they resisted the protracted force 9 gale. It`s very difficult to achieve this, if a farsighted shipowner will not give most attention to this quality to the prejudice of some other requirements. It`s necessary to remember, that stability is substantial only for safety, but not for rolling characteristic. This means a compromise between stability, propulsion and price. Most powerboats are designed presently on speed, maximum for tonnage ships and depending on water-line length. Speed is the factor of motor ship safety during an ordinary cruise trip, because the more fast is the yacht, the less risk is to get in an unexpected severe storm, which can become the serious test both for a ship and for his crew. Most motor boats are faster than sailing yachts and, as a rule, have time to sail to the shelter. The only exception from this rule is a such gale, which get suddenly up or almost suddenly, often because of intensive and quickly mooving second cyclone development. Such gales can be very localize and to last short, but sometimes they result in the considerable damages of yachts.

In order a yacht behaved correctly and predictable during a gale, it`s necessary to know, how yacht`s technical features influence its performanc in extreme conditions. High speed (20-30 knots) usually requires gliding outlines with almost flat bottom or a little V-type. At sufficient power (which is achieved now due to high-speed diesels or, what is more simple, though more dangerous, due to petrol motors) dynamic forces can lift up the ship of not too heavy construction like a surfing board at sliding from a wave. While gliding, a yacht does not submit to the law of high speed dependence on water-line length already. Such ship acquires additional stability due to dynamic forces of pressure on a bottom. They provide excellent initial stability, because on sharp or rounded shoulders large forces of maintenance are created, as on "wings", there`s an instantaneous straightening moment at a careen. However, if skimming boat will be thrown by a wave on a side, this tendency to straighten will not be expressed so good, therefore the first rule at sailing with an engine is deviation from a great heel on roughness. Another factor, necessary for skimming, is small weight. Small weight is important factor of good floatation and right mean for navigability achievement. There are also other problems. At some engine power the highest speed is achieved at absolutely flat bottom, but then a sea surface must be completely even, what can`t be in the nature. Therefore even first powerboats with sharp shoulders had V-type entrance, which decreased to the stern, turning into the flat bottom. At rapid motion on a wave the powerboat and its crew feel the strong percussion overloads.

Then American designer Ray Hunt offered so-called "deep V", which guaranteed the V-type entrance along all length of a hull. It`s possible to distinguish a ship with deep V by transom, from which a bottom at an obtuse angle goes obliquely into water. This simple and, it would seem, natural improvement gives huge possibility to improve gliders navigability. Dick Bertram showed powerboats superiority of Ray Hunt construction in the races of modern marine motor boats. Such powerboats require a little more power for going out on gliding, but additional consumption of fuel disturbs almost no driver. Gliders with a “deep V” have improved rolling characteristic and navigability. The same way modern light sailing yachts are in a great deal more nautical, than there heavy, maintaining any overload, predecessors. It doesn`t mean that fast swimming against the wind became easier now. But powerboats with “deep V” at identical sizes and identical other parameters at a bad weather can sail against the wind faster, than other powerboat type.

Fashion influences the world of boats greatly. Modern fashion complicated the problem of good ship creation. It`s hard for judicious designers to show commodity to not well-informed public to full advantage. A yacht looking like a shell, not always will manage a raging element. Sun-visor, moved before the deck-house windscreen out, a pplied in so many modern projects, operates as an effective lever, by means of which striking wave easily tears away the deck-house roof. The most often disrepair of boat in a sea is interruptions of fuel receipt by the engine. Furious rolling at a bad weather multiplies possibility of suspension appearance, mixed of fuel and sediment in dirty fuel tanks, as a result filters or even fuel pipes from the side of fuel tank are stopped up. Be ready for this. Make sure there are spare elements of fuel filters on board, then you will be able also to clean present elements. Ascertain, that you have means to blow out or to clear pipeline of fuel tank. It`s enough sometimes to drag a wire through a gate valve. Permanent attention to the filters will help you to prevent their corking in the most inappropriate moment.

It`s possible to add in conclusion, that amount of correctly constructed types of motor yachts, which combine high speed and comfort with indeed good navigability, is increased. But for demonstration of good qualities small design weight both of motor boats and sailing yachts must not be changed in operational process. Weight of improvements (either it`s fantasy of enthusiastic yachts dealer or equipment gradually acquired by an owner) can notedly multiply common displacement. If it happened after designer completed all calculations, stability can become worse sharply, and an owner will be deprived of so desirable speed, which he paid for.