Advanced Marine Vehicles

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HIGH SPEED CATAMARANS

The requirement of large deck space for a given length has led to the development of the catamarans (See Examples).

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HIGH SPEED CATAMARANS Example 2

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Length overall : 25.0 mLength waterline : 23.0 mBeam overall : 8.5 mDepth moulded : 3.0 mDraught - Hull : 1.3 mDeadwight : 33,430 kgCapacities - Fuel : 2x3,000 litres , -Fresh water : 2x1,000 litres , Passengers - Total : 255Crew : 10Service speed : 29 knotsRange : 300 n milesMain engines : 2xCaterpillar 3412E 820Kw at 2,300 rpmAuxiliary power : 2xPerkins 4GTM 45kW

HIGH SPEED CATAMARANS Example 2 Particulars

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HIGH SPEED CATAMARANS Geometry

•Each one of the two hulls, called demihull

•Demihull an be : symmetrical, asymmetrical

•The hulls can operate insemi-planing or planing regimes.

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An important aspect of catamarans is the demihull spacing due to resistance, structures and manoeuvring characteristics.

HIGH SPEED CATAMARANS (Spacing)

As the distance between the hulls gets smaller the resistance interference becomes very unfavourable while structural problems gets easier.

Seakeeping behaviour is probably the biggest handicap of thecatamarans.

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Pitching is worse than the conventional hulls.

HIGH SPEED CATAMARANS (Spacing)

Additionally the vertical accelerations are very high on the deck side.

Wave piercing catamaran is introduced to reduce the contouring.

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Wave-piercing Catamaran

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The main current usage areas are passenger ferries and military craft.

Wave-piercing Catamaran

A wave-piercing boat hull has a very fine bow, with reduced buoyancy in the forward portions.

When a wave is encountered, the lack of buoyancy means:1. the hull pierces through the water rather than riding over the

top 2. results in a smoother ride than traditional designs, and 3. in diminished stress on the vessel and crew. 4. It also reduces a boat's wave making resistance.

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Wave-piercing Catamaran

Wav

e-pier

cing

Cat

amar

an

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SWATH SHIPS

called :

•S3, Trisec,

•LWP Catamaran,

•Semisubmerged catamaran,

•Fast displacement catamaran

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SWATH SHIPS (Configuration)

Surface piercing struts

Deeply submerged cylindrical hullBox shaped deck

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Advantages1. Small waterplane area struts give SWATH Ship a

superior behaviour in waves 2. Low wavemaking resistance

SWATH SHIPS

Disadvantages1. Large wetted surface restricts the maximum speed.2. Sensitivity to trim, and pitching

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SWATH SHIPS

SWATH

SHIP

S

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•invented by Canadian Frederick G. Creed•presented in 1938, and patented in 1946. •first used in the 1960s and 1970s as an evolution of catamaran design •used in oceanographic research vessels or submarine rescue ships

SWATH SHIPS (History)

1871-1957

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SWATH SHIPS (History)

1938 Frederick G. Creed, a Canadian, presents his idea for a small-waterplane-area twin-hull aircraft carrier to the British Admiralty. Several years later Creed is permitted to show it to the U.S. Navy, but they do not pursue the concept .

1946 Frederick Creed is awarded a British patent .

1871-1957

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1968 40m long, Duplus is launched in the Netherlands. 1200-ton Duplus a self-propelled oil exploration support vessel

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1972 Construction begins on the 190-

ton SWATH workboat SSPKAIMALINO for NUC after18 months of research byengineers at NUC and nearly2 .5 years of design andconfirmatory model testing

Launching occurs in March, 1973 .

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1991 The first of a class of 4 SWATH acoustic Surveillance ships designed by the U.S. Navy, the 71.5 m long victorious, is delivered to the Military Sealift Command .

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Finnyards delivers the first SWATH cruiseliner, the 131 m long Radisson Diamond, to Diamond Cruise Ltd .

1992

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The world's first "stealth" ship, the U.S. Navy's 50 m long Sea Shadow, an A-Frame SWATH ship built by Lockheed Missiles and Aerospace Co., is declassified and disclosed publicly, leading to a cover article in the July '93 issue of Popular Mechanics .

1993

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OverviewSea Shadow has a SWATH hull design. Below the water are submerged twin hulls, each with a propeller, aft stabilizer, and inboard hydrofoil .The portion of the ship above water is connected to the hulls via the two angled struts. The SWATH design helps the ship remain stable even in very rough water of up to sea state 6 wave height of (5.5 m) or "very rough" sea.

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Stealth shipType:572 tDisplacement50 mLength:21 mBeam:4.6 mDraft:Diesel-electricPropulsion:28 knotsSpeed:4ComplementNoneArmament:

Thank You for Your Attention!

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