Sunday, April 12, 2015

PERSHING YACHTS & SURFACE DRIVES: WHAT ARE THE ADVANTAGES?





#Pershing is one of the leading brands worldwide in the production of high-performance open-coupé #motoryachts in fiberglass, measuring 50 to 115 feet (15-35 meter) in length. The hallmark of Pershing yachts is the way they combine an outstanding sporting performance, using highly hydrodynamic hulls and powerful, innovative propeller systems, with the elegance and extraordinary livability of avant-garde interiors. Innovative design, engines which can reach up to 7,000 Hp and the use of surface propellers, water jets, and gas-turbines, give Pershing #yachts a truly sport-style trim, driving them to reach remarkable speeds up to over 50 knots. Moreover, Pershing has introduced an extremely distinctive design, maintained over the years, which makes its models clearly recognizable on the international boating scene. Pershing yachts are highly considered by clients interested in performance in terms of speed and in technological, innovative content. 





WHAT ABOUT SURFACE DRIVES

Surface Drives are among the most efficient marine propulsion systems in the world. What are Surface Drives, and how do Surface Drives work? Put quite simply, surface piercing propellers operate half in and half out of the water in the planning wake region of a boat which is just behind the boat transom. Having the propeller at the water surface level reduces drag and the vessel draft, making Surface Drives suitable for multiple applications where the owner is looking to reduce fuel consumption, increase speed and create a more efficient vessel. 

There are advantages and disadvantages with any propulsion system for water crafts. But for fast planning vessels, surface propulsion has several distinct advantages over its competitors in the pro- pulsion marketplace. The perfect vessel for this propulsion has a sport deep V hull, with a very low power-to-weight ratio, like Pershing yachts. Quickly summarizing we can say that surface-piercing propeller design reduces underwater drag by 50% compared to conventional submerged propeller drive systems (example: Shaft driven system).

The only surfaces to contact the water are propeller blades and a protective skeg. This results in higher overall speed, quicker acceleration, and a better payload to power ratio... and... less drag significantly improves fuel economy while lowering operating costs. Overall from a Surface Drive system, you can expect greater fuel efficiency for a boat capable of achieving a cruisie speed higher than 35/40 kn, zero cavitation and shallower drafts, less maintenance and exceptional astern performance, making Surface Drives the smart choice.



TRIMMABLE PROPELLER SHAFT

The propeller shaft is vertically adjustable, allowing selection of the optimum thrust angle and boat trim for varying load and sea conditions.

POSITIVE THRUST STEERING

Unlike conventional systems that vector propeller thrust off of a rudder, the Surface Drives angles in the direction of motion, maximizing steering control and response. 

RESPONSIVE MANOEUVRABILITY

Propellers are located aft, behind the hull, increasing steering leverage and improving maneuverability at any speed. 

SHALLOW WATER CAPABILITIES

The drive has a trimmable propeller shaft and no fixed underwater append- ages, requiring significantly less draft than conventionally powered hulls. 
BIGGER INNER VOLUME AND IMPROVED SEAKEEPING

The engines are located in the aft part of the boat, this improves the technical compact installation and maximizeing the space for the general layout of cabins in the yacht. The boat becomes smoother in seakeeping because the center of gravity is closer to the transom. 

NO CAVITATION

Cavitation is the rapid formation and depletion of air bubbles produced by the turbulent flow of a spinning propeller. With surface propulsion, half of the propeller is above the surface, and the surface blades create a super-ventilated environment rather than one of potential cavitation. This eliminates the risk of propeller damage due to cavitation, providing lower maintenance issues over time. 
















PERFORMANCE "SPEED WITH COMFORT" AND USAGE


  • For fast yachts over 40 knots of top speed, Surface Drives is the best solution. Especially if the boat is designed to achieve more than 45 knots. At those speeds, traditional immersed props are damaged by cavitation and vibrations and waterjet systems are heavy and not efficient in the same way as a surface drive system. 
  • Higher cruise speeds: by using carefully designed and developed varying pitched, fixed blade propellers, Surface Drives produce a higher cruise speed with reduced fuel consumption.
  • Easy adjustment to any load condition: capacity to change configuration equals to having best performances under any load condition.
  • Quicker to plane: trimming the propeller shaft means re-direct pushing force downwards, incrementing nose-down momentum makes crafts quicker to plane with minimal lazy speed range (i.e. 10 seconds from idle to 45 knots for a 22 tons mono-hull with 2 x 1200HP engines).
  • Steerage by the positive thrust of the propeller and not by the propeller thrust to the rudder. This is equivalent to sport car rack-and-pinion steer- ing performance.
  • No limitations to shaft angle, blade top clearance, designed to restrict selection of optimum diameter propeller.
  • Ability to adjust submergence to match horsepower out put permits con- version of more thrust as appropriately needed also while underway. 


BRIEF HISTORY

When we speak about marine propulsion systems we usually refer to conventional underwater propellers being the most common and worldwide known system used for marine application. A conventional system like this, if well designed can allow good performance for top speeds of about 35 knots and in few cases up to 40 knots. The technology to move into the realm of over forty, fifty, sixty knots and above are now available and have been proven. The conventional propulsion system of fully submerged propeller and inclined shaft has been left behind for the development of Surface Drive systems particularly Arneson Drives being the first articulated surface system released into the market. Howard Arneson thought “I could not find the sweetheart spot that’s right for all conditions” and also it needed rudders to steer with. After changing the spot and angle several times, he figured that if he could develop a trimming system, he’d be on the way. A key element in his invention was a ball and a socket arrangement, which when coupled with a constant velocity joint would allow the operator to change the angle and achieve the trimmability Arneson was seeking. The final configuration for the ASD was conceived in 1979 and the first models were constructed and tested in early 1980. Shortly after production began on the smallest model which we now call ASD 6. Initially tested on many different racing applications, ASD’s were immediately successful in a number of racing cir- cuits around the world. From their initial debut, numerous offshore class 1 world championship and two of the world famous Miami-Nassau-Miami offshore races were won on stock, fully warranted, factory 3Arneson Drive units.


 Pershing dealer with Pershing Yachts for sale in Florida: Miami, Fort Lauderdale, Palm Beach, Sarasota, Tampa Bay & Naples, FL  

Pershing dealer with Pershing Yachts for sale in the NE United States: Hamptons, Long Island Sound, New York, Newport & Nantucket


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