STEALTH 380 RUV hybrid - STEALTH technology 380 hybrid 10 12 13.pdftechnology As the fi rst commercial diesel-electric propulsion systems for small vessels are now commerically available,

STEALTH 380 hybrid

The design objective of this craft is to

provide a small, effi cient passenger

vessel with the lowest possible Car-bon Emissions in anticipation of ever-

increasing environmental legislation,

whilst at the same time providing

levels of passenger comfort with re-

duced journey time comparable with

current vessels.

The STEALTH 380 hybrid is based on the

proven effi cient HYSUCAT (HYdrofoil

SUpported CATamaran) hull used by

the STEALTH 520 RUV, but extends the

concept further with the introduction

of a hybrid diesel-electric propulsion

system.

This innovative product should not

only serve operators and users alike,

objective

but also avail itself of eco-friendly technologies that are de rigueur in today’s environmentally conscious society.

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The most signifi cant factor in reduc-

ing operating costs and CO2 emis-

sions is the reduction of the vessel’s

fuel consumption – more specifi cally,

a reduction in the fuel consumption

per passenger per journey.

Unfortunately, at present, propulsion

systems technology has not devel-

oped enough to allow a simple solu-

tion to this problem. The design of the

STEALTH 380 hybrid will use a combi-

nation of the following design factors

to meet this requirement:

design concept

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The hull design is based on cata-

maran hulls as these hull forms give

a characteristically soft ride (most

notably in rougher water), a pro-

portionally larger deck area for a

given hull length (for increased

passenger space) and a lower run-

ning resistance than a convention-

al monohull.

Using the HYSUCAT principle, hy-

drofoils are used to assist in gener-

ating a high proportion of the lift

required for the vessel to plane.

As this lift is generated at higher ef-

ficiency values than the hull plan-

ing surfaces, the overall efficiency

of this hybrid hull/foil combination

is further increased.

efficient stealth hull technology

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Virtually all the work done to date on environmentally conscious propulsion systems relates to electric-powered sailing vessels or large, well under-stood, diesel-electric systems (which have been in use for 100-odd years) used in locomotives, large mining ve-hicles, certain types of tugboats, etc. The big difference with small-craft is the requirement to use batteries as a means of energy storage and Photo-Voltaic (PV) panels as an alternate energy source which is not possible on large instillations.

The automotive industry has gone an-other route and use an electric en-gine for low-power requirements and a smaller (than normal), conventional (petrol or diesel) engine for higher power requirements (longer distance or higher speed) – hence the term hybrid.

effi cient low co2 emmisions enginetechnology

As the fi rst commercial diesel-electric propulsion systems for small vessels are now commerically available, this technology-type will be used for the STEALTH 380 hybrid - the photo below shows and example of a Steyr Mo-tor’s (Austria) hybrid propulsion pack-age consisting of a 7kW electric en-gine (green) directly connected to a 185kW diesel engine (grey)

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STEALTH yachts have extensive expe-

rience with the use of large surface

propellers for effi cient high-speed

propulsion.

Electric motors produce a high output

torque at low speeds. This requires a

much larger propeller on any electri-

cally driven boat compared to con-

ventional motors. The disadvantage

being that the propeller is over-sized

for higher speeds.

With the use of surface propellers, the

unique requirements for both electric

engine propulsion at lower speeds

and diesel engine propulstion high-

speeds can be uniquely combined to

match the power output from a hy-

brid drive system!

effi cient propulsion technology

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The parallel diesel-electric hybrid sys-tem backs up the low-emission, elec-tronically-controlled diesel engine with an independent electric propulsion motor.

The propulsion motors are connected together and either independently or in combination they drive the propel-ler shaft.

The advantage of this two-tier system is that it recognizes that the strength of the conventional diesel engine lies in its high-end output and does not com-pete with this – it adds a zero-emission, quiet electric engine to the power train for use in slow speed maneuver-ing and motoring when the use of the diesel engine is ineffi cient.

The diagram, representing the Steyr Motor’s Hybrid Marine Propulsion sys-tem, shows the typical components installation. The chart indicates the various engines installed in compara-tive craft.

hybrid power concept

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Electric power only: In low-speed elec-tric propulsion mode, operation will be quieter with zero CO2 emissions. The die-sel engines are not used and power is drawn from light-weight Lithium-based batteries. Operational speed will be 6 knots for a duration of two hours. This mode is intended for harbor use and slow approach and departure speeds in high traffi c areas or environmentally sensitive areas.

Diesel engine with electric engine driven as an alternator to charge batteries: This is the normal cruise mode at 28 knots in open water. The diesel engine operates at its most effi cient point (lowest fuel con-sumption per unit power produced thus lowest possible CO2 emissions) whilst us-ing the electric engine in “reverse” mode as a generator to charge the propulsion batteries.

Diesel engine only: This mode will occur if no battery-charging and no additional propulsive power is needed but will not be a normal operating mode.

modes of operation

Diesel engine supplemented by addi-

tional power form the electric engine: This

mode can be used where more power

is needed than can be supplied by the

main diesel engine – the output from the

electric engine can be added to that of

the diesel engine.

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There is no degradation of cruising (higher speed) operational perfor-mance as propulsion in this mode is from the normal diesel engines.

Electric propulsion will take over at precisely the point in the diesel en-gine power equation where it is be-coming increasingly ineffi cient and specifi c fuel consumption in relation to output power is poor.

When in electric propulsion mode, there will be quieter operation, en-hanced low speed maneuverabil-ity and other non-effi ciency related benefi ts.

Propulsion power will always be in-stantly available as it will be possible to run the vessel for several hours with the electric motors using battery power.

advantages

Alternative zero or low emission en-ergy sources can be used for battery charging such as PV solar panels or shorepower when docked.

A supplementary advantage of this diesel-electric hybrid system is that a third auxiliary engine in the form of a generator is not added to the ves-sel for powering air-conditioning and other on-board electrical power sys-tems – in the second operating mode described above (the normal operat-ing cruise condition), electrical ener-gy for these systems will be provided by the electric propulsion motor oper-ating in “reverse” mode as a genera-tor.

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environmental impact

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principle characteristics

Length overall (LOA): 11.8m 38ft 6inBeam Maximum: 4.2m 13’ 10”Dry Weight: 7,000kg 15,400 lbs

Power: 2 x 280hp (185kW) Diesel plus 2 x 10hp (7kW) ElectricDrive system: STEALTH surface drive systemHydrofoil system: Tandem hydrofoil setSpeed: Maneuver (Elec) 6 Kts - Cruise 28 Kts - Max 34 KtsCapacity: 2 Crew and 30 PassengersTime on electric power: 2 hours

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contact:

www.stealth-technology.comThis document is not contractual. All descriptions and illustrations are only indicative.

We reserve the right to modify or improve our product without notice. November 2010