DAVID R. LAVIS BAND LAVIS DIVISION OF CDI MARINE

DAVID R. LAVIS BAND LAVIS DIVISION OF CDI MARINE
FIFTY YEARS & MORE OF HOVERCRAFT DEVELOPMENT SNAME and IHS Dinner Meeting 11 MAY 2011 THANK YOU BILL AND GOOD EVENING LADIES AND GENTLEMEN. I WILL START BY TELLING YOU THAT THERE ARE ESSENTIALLY TWO TYPES OF HOVERCRAFT. 1. THE AMPHIBIOUS AIR CUSHION VEHICLE OR ACV AND 2. THE NON-AMPHIBIOUS SURFACE EFFECT SHIP OR SES. I WILL TALK ABOUT BOTH TODAY, BUT MOSTLY ABOUT ACVs I HAVE BEEN IN THE HOVERCRAFT BUSINESS NOW FOR MORE THAN 52 YEARS AND REALIZE THAT THERE ARE THREE THINGS THAT HAPPEN WHEN YOU GET OLDER. THE FIRST IS THAT YOU START TO LOSE YOUR MEMORY AND……………… IT’S STRANGE, BUT I CAN’T REMEMBER THE OTHER TWO. HOWEVER, I DO HAVE A LOT TO SHOW YOU THIS EVENING. SO, YOU WILL HAVE TO EXCUSE ME FOR REFERING OR READING FROM MY NOTES A LOT. BUT, AT LEAST, I WILL GET MY FACTS, OR MOST OF MY FACTS, STRAIGHT. DAVID R. LAVIS BAND LAVIS DIVISION OF CDI MARINE

CONTENTS OF PRESENTATION
EARLY ENDEAVORS RAPID EXPANSION MAJOR CHALLENGES MOST SIGNIFICANT CONTRIBUTIONS MANY ACV & SES PHOTOS & VIDEOS RECENT DEVELOPMENTS CUSHION SEALS PROPULSION MANEUVERING CONTROL DESIGN SOFTWARE SUMMARY, CONCLUSIONS & THE WAY AHEAD WHAT I WILL PRESENT THIS EVENING IS LISTED HERE: IT INCLUDES: THE ACHIEVEMENTS OF SOME OF THE EARLY HOVERCRAFT INVENTORS. PLUS A DESCRIPTION OF THE RAPID EVOLUTION THAT TOOK PLACE IN THE 1960s AND 70s. THIS WILL INCLUDE A DESCRIPTION OF THE MAJOR TECHNICAL CHALLENGES AND THE CONTRIBUTIONS THAT HAVE BEEN MADE FROM AROUND THE WORLD. I WILL THEN DISCUSS PROGRESS THAT HAS OCCURRED IN JUST THE LAST 15 OR SO YEARS. IN THIS REGARD, MY PRESENTATION WILL COVER ONLY THOSE SYSTEMS THAT ARE UNIQUE TO ACVs AND SES. I WILL CONCLUDE WITH A SUMMARY AND CONSIDERATIONS FOR THE FUTURE. I WILL BEGIN MY TALK BY TELLING YOU THAT I COME FROM A FAMILY OF BOAT BUILDERS WHO STARTED THEIR COMPANY IN 1875 IN SOUTH DEVON ENGLAND. IT WAS NOT UNTIL 1936, HOWEVER, THAT MY GRANDPA STUMBLED UPON THE CONCEPT OF AMPHIBIOUS ASSAULT.

EARLY ENDEAVORS 1936 – Grandpa Lavis stumbles onto the idea of Amphibious Assault WELL, MY GRANDPA DID RUN A BOAT BUILDING BUSINESS WELL, MY GRANDPA DID RUN A BOAT BUILDING BUSINESS, BUT HIS NAME WAS NOT CHARLIE CHAPLIN.

EARLY ENDEAVORS SR-N1 in 1959 RINA PAPER LISTS 30
INVENTORS WITH PATENTS PRIOR TO 1953. AT LEAST 12 OTHERS DID NOT FILE PATENTS. 8 PATENTS FEATURED FLEXIBLE SKIRTS BEFORE SR-N1 CROSSED THE ENGLISH CHANNEL WITHOUT A SKIRT IN 1959. SO, I WILL CONTINUE WITH THE ENDEAVORS OF THE EARLY INVENTORS. MY EXAMINATION OF THIS WAS HELPED SIGNIFICANTLY BY THE FACT THAT IN 1995, (16 YEARS AGO) THE U.S. DEPARTMENT OF JUSTICE ENGAGED ME AS THEIR EXPERT TECHNICAL WITNESS TO DEFEND THE U.S. ARMY AND NAVY AGAINST A PATENT INFRINGEMENT SUIT CONCERNING ACV SKIRTS. (McCreary) THIS GAVE ME, WITH HELP FROM NSWC & DOJ, THE OPPORTUNITY TO CONDUCT AN EXTENSIVE SURVEY OF PRIOR ART THAT I HAVE SUMMARIZED IN A TABLE IN A PAPER THAT I DELIVEREDTO A RINA CONFERENCE IN LONDON IN NOVEMER OF 2009. THE TABLE LISTS AN AMAZING TOTAL OF 30 INVENTORS THAT HAD THE IDEA OF USING AIR TO REDUCE THE DRAG OF OVER-LAND OR OVER-WATER VEHICLES, PRIOR TO THE SIGNIFICANT GROUND-BREAKING WORK OF CHRISTOPHER COCKERELL IN THE UK, WHICH BEGAN IN 1953 AND WAS PATENTED IN 1955. COCKERELL, WHO WAS LATER KNIGHTED FOR HIS WORK, EMPHASIZED THE NEED FOR A THICK CUSHION OF AIR TO REDUCE DRAG. IT WAS THIS SIGNIFICANT REALIZATION, OF COURSE, THAT QUICKLY LAUNCHED A NEW WORLD-WIDE INDUSTRY. NOT ALL THE EARLY INVENTORS PATENTED THEIR WORK, HOWEVER, AND THEY ADD, AT LEAST, ANOTHER 12 TO THE LIST OF 30, THUS GIVING AN AMAZING TOTAL OF 42 INVENTORS DOING WORK ON HOVERCRAFT BEFORE COCKERELL BEGAN HIS WORK IN 1953. I WAS ALSO AMAZED TO FIND THAT BEFORE THE SAUNDERS-ROE SR-N1 CROSSED THE ENGLISH CHANNEL WITHOUT A SKIRT IN 1959, THERE WERE A TOTAL OF EIGHT PATENTS ISSUED TO DIFFERENT INVENTORS CLAIMING THE VIRTUE OF FLEXIBLE SKIRTS.

HERE IS THE LIST OF INVENTORS MENTIONED IN MY RINA PAPER.
Date of Patent Name and Location Subject 1716 Swedenborg, E., Sweden Plenum Craft Illustration 1876 Ward, J., San Francisco, USA Plenum Machine Idea 1877 Sir John Thornycroft, UK Air Lubricated Hull 1880 Girard, L., France Rail Car 1882 De Laval, G., Sweden 1888 Walker, J., Texas, USA Air Lubricated Hull Idea 1889 Barre, M.C.A., France 1897 Culbertson, USA Sidewall Craft Idea 1902 Therye, C., France 1906 Schroeder, F.W., Germany (British Patent) Air Lubricated Hull Design 1907 Clark, J., USA Craft With Annular Ducts 1908 Worthington, C., USA Rail Car With Flexible Seals Porter, J.R., UK Annular Jet Craft With Flexible Skirt 1909 Wunderlich, A., Germany Plenum Craft 1912 Alcock, A.U., Perth, Australia Levapad Craft 1913 Eells, A.F., USA 1916 Von Thomamhul, D.M., Austria Air Lubricated Torpedo Boat 1921 Gambin, M.A., France Sidewall Craft 1922 Breguet, L., Paris, France Plenum Craft With Flexible Seals Trask, F.G., North Dakota, USA 1925 Casey, V.F., Minneapolis, USA Air Lubricated Hull With Air Recirculation 1927 Tsiolkovski, K.E., Russia 1928 Nicin, V., Dresden, Germany Plenum Car Giving Reduced Wheel Load Warner, D.K., Sarasota, USA Sidewall Craft with Spring-Loaded Rigid Seals 1935 Birrard, J., France Sidewall Craft Design Kaario, T.J., Finland Plenum/Ram Wing Craft Date of Patent Name and Location Subject 1939 Courant, France Sidewall Craft with Mechanical End Seals 1942 Cristadoro, C.C., Venice, CA, USA Sidewall Craft With Flexible End Seals 1944 Brian, W.S. & Birk, F.J., Owensboro, KY, USA Sidewall Craft 1952 Bondat, A.J., France Snow Skis With Multi-Plenum Air Cushions 1954 Seck, W.G., Canton, Ohio, USA Hovering Vacuum Cleaner by Hoover Co. 1955 De Lima, R.A., Brazil Peripheral Jet and Aircraft Landing Gear Cockerell, C., UK Peripheral Jet and Sidewall Craft Roe, A.V., Canada Peripheral Jet Craft 1957 Beardsley, M.W., Severna Park, MD, USA Craft With Peripheral Jet & Membrane Sheet Weiland, C., Switzerland Craft With Labyrinth Seal Bertin, M., France Craft With Multi-Cell Plenum Skirt 1958 Jay, D.J. & Pelthman, H.W., USA Craft With Multi-Plenum Latimer, C.H., Needham, UK Craft With Flexible Skirt Petersen, T.K. & Smith, P.L., Tulsa, OK, USA Cargo Handling Conveyor 1959 Gaska, C.W., Michigan, USA Vaughen, J.F., Irving, Texas, USA Hover Pallet With Flexible Seals 1960 Ford, A., USA High-Speed Sidewall SES Hurley, R.T. & Agni, E.S., USA Mackie, H.A. & Veryzer, R.W., USA Wheel Barrow With Flexible Skirt McCreary, N.B., Arkansas, USA Plenum Craft With Flexible Skirt 1962 Lewis, N.W., USA Craft With Finger Skirt - Vertical Bliss, D.S., of HDL, UK Craft With Finger Skirt - Inclined HERE IS THE LIST OF INVENTORS MENTIONED IN MY RINA PAPER. IT IS A BIT OF AN EYE TEST, BUT THE FIRST ON THE LIST IS AN INVENTOR FROM SWEDEN WHO DISCLOSED HIS WORK NEARLY 300 YEARS AGO. AND THE FIRST TO MENTION THE USE OF FLEXIBLE SKIRTS WAS WORTHINGTON IN THE USA IN 1908. THIS IS SHOWN IN RED TEXT AS ARE THE OTHERS WHO MENTIONED SKIRTS BY OR BEFORE 1959. Dr. William Bertelsen first piloted his "flying aeromobile" in 1958 Melville Beardsley 1957 Patent , Severna Park

CRAFT WITH FLEXIBLE SKIRT BY PORTER, UK, 1908
FABRIC SKIRT BUT PERHAPS THE MOST INTRIGUING WAS BY PORTER OF THE UK WHO, ALSO IN 1908, PATENTED A FLYING MACHINE WITH AN INFLATED PERIPHERAL CURTAIN AS SHOWN BY THIS ILLUSTRATION FROM HIS PATENT.

FLEXIBLE END SEALS BY BREGUET, FRANCE, 1922
IN 1922, BREGUET, IN FRANCE, PATENTED A TWIN-HULL FLYING BOAT CONCEPT. THIS HAD INFLATED END SEALS FORE AND AFT TO TRAP PUMPED AIR TO ASSIST TAKE OFF AND LANDING OVER LAND AND OVER WATER. THE AIR CUSHION IS SHOWN HERE IN YELLOW, THE AIR SUPPLY FAN IN RED, AND THE HULLS AND ONE WING IN BLUE.

FLEXIBLE END SEALS AND CUSHION DIVIDER BY CRISTADORO, USA, 1942
Transverse Seal CHRISTADORO, A FAMOUS US SCULPTOR AND INVENTOR FOR DISNEY WORLD, PATENTED A VEHICLE WITH FLEXIBLE END SEALS IN 1942. THIS PATENT WAS FOR AN AIRSCREW-PROPELLED SES-LIKE VESSEL WITH RIGID SIDEHULLS. IT FEATURED INFLATED END SEALS AND A TRANSVERSE FLEXIBLE SEAL AMIDSHIPS. THIS SEAL SPLIT THE CUSHION INTO FORE AND AFT COMPARTMENTS WITH EACH FED AIR BY A SEPARATE FAN FOR IMPROVED PITCH STABILITY. HE PROBABLY DID NOT REALIZE, HOWEVER, THAT, WHEN UNDER WAY, THE TRANSVERSE SEAL AMIDSHIPS WOULD ALSO ACT TO IMPEDE LOSS OF CUSHION AIR FROM UNDER THE STERN SEAL AND THUS REDUCE DRAG, AS WE DISCOVERED FOR OURSELVES IN THE MID 1990s FOR BOTH SES AND ACVs. THE INFLATED BOW SEAL WAS ALSO SAID TO PROTECT THE HULL FROM SLAMMING LOADS . THIS, AS I SAID, WAS IN 1942. THE DESCRIPTION GIVEN IN THE PATENT ABOUT THE OPERATIONAL BEHAVIOUR OF THE VESSEL, IN CALM AND IN ROUGH WATER, WOULD STRONGLY SUGGEST THAT THE CONCEPT HAD ACTUALLY BEEN REDUCED TO PRACTICE. Air Supply Fans

AVRO PROJECT-Y, FLYING SAUCER (1952 to 1962, CANADA)
Click for web source Click for web source ANOTHER INTRIGUING DISCOVERY WAS THAT, IN 1952, THE CANADIAN DIVISION OF THE UK FIRM OF A.V. ROE LAUNCHED A PROJECT HEADED BY AN ENGLISHMAN NAMED JOHN FROST. IT WAS TO DEVELOP A SUPERSONIC FIGHTER-BOMBER THAT COULD TAKE OFF AND LAND ON A CUSHION OF AIR, AND ACCELERATE TO HIGH SPEEDS AT HIGH ALTITUDES. THE FIRST MANNED TEST FLIGHT DID NOT OCCUR, HOWEVER, UNTIL 1960. BECAUSE THE ANALOG CONTROL SYSTEMS AVAILABLE AT THE TIME COULD NOT PROVIDE ADEQUATE CONTROL FOR TRANSITION OUT OF GROUND EFFECT, THE PROJECT WAS CANCELLED IN 1962. THE FOCUS OF THE PROJECT, OF COURSE, HAD BEEN TO FLY OUT OF GROUND EFFECT, AND JUST RUNNING AT HIGH SPEED SOME 5 FEET OFF THE GROUND WAS, IRONICALLY, NOT CONSIDERED TO BE AN IMPORTANT ATTRIBUTE ON ITS OWN.

CURTIS-WRIGHT MODEL 2500 AIR CAR (USA) Operated in 1959 with 8-inch Flexible Skirt
Click for Web Source ANOTHER EXAMPLE OF EARLY DEVELOPMENT IN NORTH AMERICA WAS THE CURTIS-WRIGHT AIR CAR OR GROUND EFFECT MACHINE (GEM) AS THEY WERE THEN KNOWN AS IN NORTH AMERICA. TWO PROTOTYPES OF THIS CAR WERE DELIVERED TO THE U.S. ARMY AND OPERATED IN 1959 WITH AN 8-INCH FLEXIBLE SKIRT.

EARLY ENDEAVORS (Contd.)
1952 – 1960 ACV (GEM) DEVELOPMENT CANADA (AV ROE); UK (Cockerell), USA (CURTIS-WRIGHT, GM, FORD, CONVAIR, MARTIN, BELL, GD, H. Chaplin, Beardsley, Bertelsen) 1960 – HIGH-SPEED SES DEVELOPMENT USA NADC (A. Ford) & UK HDL (Cockerell) 1960 – 1970 RAPID EXPANSION UK, USA, CANADA, SWEDEN, NORWAY, FRANCE, JAPAN, RUSSIA, CHINA, AUSTRALIA DURING THE 1950s, THERE WERE SEVERAL OTHER US COMPANIES AND INDIVIDUAL INVENTORS INVOLVED IN GEM DEVELOPMENT. IT WAS CLOSE TO THIS TIME THAT ALLEN FORD, OF THE U.S. NAVAL AIR DEVELOPMENT CENTER, BEGAN INVESTIGATING THE CAPTURED AIR BUBBLE (CAB) RIGID-SIDE HULL SES AS A SOLUTION TO MINIMIZE LIFT POWER FOR HIGH-SPEED OPERATION OVER WATER. I BELIEVE ALLEN IS HERE THIS EVENING. SOON, OTHER COMPANIES AROUND THE WORLD, AS LISTED HERE, WERE ALSO EAGERLY DEVELOPING NEW CONCEPTS.

TECHNOLOGY PROGRESSION
1959 UK UK 1963 USA 1980 USA 2004 FINLAND INITIALLY, ACV DEVELOPMENT MOVED RAPIDLY FOLLOWING THE SR-N1, THE FIRST PRACTICAL MAN-CARRYING ACV, TOP LEFT. THIS CRAFT WAS LAUNCHED IN 1959 BY SAUNDERS-ROE, THE COMPANY THAT I JOINED THAT SAME YEAR. IN THE 1960s, DEVELOPMENT IN THE UK WAS REMARKABLY FAST AS MORE AND MORE COMPANIES GOT INVOLVED AND THE TECHNOLOGY PROGRESSED SIGNIFICANTLY WITH THE INTRODUCTION OF THE FLEXIBLE SKIRT. SAUNDERS ROE, FOR EXAMPLE, WAS LAUNCHING ABOUT ONE NEW TYPE OF ACV EVERY YEAR, WHICH IS ABSOLUTELY PHENOMENAL BY TODAY’S STANDARDS. ALSO, BY 1963, BELL AEROSPACE, IN THE USA, HAD BUILT A CRAFT (TOP RIGHT) THAT COULD FLY IN AND OUT OF THE DRY WELL OF AN AMPHIBIOUS LANDING SHIP. AND, BY 1968, THE SR-N4 VERY LARGE PASSENGER-CAR FERRIES WERE IN SUCCESSFUL OPERATION ACROSS THE ENGLISH CHANNEL. HOWEVER, BEFORE WE PROCEED FURTHER, IT WOULD BE GOOD TO TAKE STOCK OF THE MAIN CHALLENGES FOR FURTHER DEVELOPMENT.

THE PRINCIPAL CHALLENGES
HIGH COST (LOW EFFICIENCY) PROPULSION LOW RELIABILITY OF HIGH-POWERED SYSTEMS NEED TO REDUCE AIRBORNE NOISE PERFORMANCE SENSITIVE TO WEIGHT GROWTH TWO ADDITIONAL SYSTEMS (SKIRTS + AIR SUPPLY) SKIRT MAINTENANCE (MINIMIZED BY GOOD DESIGN) SPEED LOSS IN A SEAWAY CHALLENGING MANEUVERABILITY SAFETY (HIGH-SPEED NAVIGATION) THE FIRST MAJOR CHALLENGE WAS HIGH ACQUISITION & OPERATING COST SINCE, DESPITE VERY LOW DRAG, POWERING REQUIREMENTS WERE LARGE AND EXPENSIVE. THIS WAS BECAUSE AIRSCREWS WERE NEEDED FOR AMPHIBIOUS CAPABILITY AND THEY WERE VERY INEFFICIENT AT ACV SPEEDS COMPARED TO THEIR EFFICIENCY AT AIRCRAFT SPEEDS. THEY WERE ALSO OFTEN UNRELIABLE AND VERY NOISY. ALSO, AS WITH ALL HIGH-SPEED CRAFT, THEIR PERFORMANCE WAS VERY SENSITIVE TO WEIGHT GROWTH . Slide change ALSO, UNLIKE MOST OTHER HIGH-SPEED CRAFT, THEY WERE BURDENED WITH THE COST, WEIGHT & MAINTENANCE OF TWO ADDITIONAL SYSTEMS…. THE CUSHION SKIRT AND THE AIR SUPPLY FANS AND REQUIRED POWER SOURCE. AND THEIR LOSS OF SPEED, AS SEAS INCREASED, DUE TO WAVE PUMPING OF THE CUSHION, WAS MORE THAN DESIRABLE. ALSO, MANEUVERABILITY AND HIGH-SPEED COLLISION AVOIDANCE WAS OFTEN A SERIOUS CHALLENGE.

SOME OF THE MOST SIGNIFICANT DEVELOPMENTS 1962 to 1977
HDL Bag-Finger Skirt (ACV & SES) – 1962 Denny D-2 GRP Hulls (SES) – 1962 Airscrew-Weyroc Centrifugal Fans (ACV & SES) – 1962 SRN-Series Integrated Lift & Propulsion (ACV & SES) – 1962 SRN-Series Integrated Maneuvering Controls (ACV) – 1962 US Navy XR-Series of Experimental SES – Bell Skimmer Shrouded Propellers (ACV) – 1964 Aerojet General Application of Water Jet Propulsion (SES) – 1966 Aerojet General Ride Control (SES) – 1966 SO WHAT WERE THE MOST SIGNIFICANT DEVELOPMENTS THAT HELPED OVERCOME THESE CHALLENGES? ON THIS & THE NEXT SLIDE, I HAVE LISTED WHAT I BELIEVE TO BE AMONG THE MOST SIGNIFICANT DEVELOPMENTS FOLLOWING THE EARLY WORK AT HDL AND SAUNDERS ROE. I WILL SHOW PHOTOS OF SOME OF THE CRAFT INVOLVED SHORTLY. THIS FIRST SLIDE LISTS THE SIGNIFICANT DEVELOPMENTS THAT TOOK PLACE IN THE 15-YEAR PERIOD FROM 1962 TO 1977. THE FIRST, AND POSSIBLY THE MOST SIGNIFICANT, WAS THE BAG AND FINGER SKIRT, PATENTED BY DENYS BLISS OF HDL IN THIS REPLACED THE COMPLICATED PERIPHERAL JET SKIRTS USED BY BHC UNTIL ABOUT 1964, Slide Change……………………………….. NEXT THE SRN-2 AND SUBSEQUENT SRN-SERIES INTEGRATED LIFT & PROPULSION SYSTEM THAT PERMITTED MORE EFFICIENT OPERATION, Slide change …………………………………… THEN THE MORE EFFICIENT AND LESS NOISY SHROUDED PROPELLERS ON THE BELL SKIMMER ACV DERIVED FROM THEIR TILT-WING AIRCRAFT PROGRAM, Slide change………………………………………. NEXT IS THE U.S. NAVY’S 3KSES PROGRAM, THAT GENERATED VERY SIGNIFICANT TECHNOLOGY, Slide change ……………………………………… AND NEXT IS THE BELL CONTROLLABLE BOW THRUSTERS ON THE JEFF(B) ACV. Aerojet 100A, Bell 100B and Rohr 3KSES Programs – Hovermarine GRP Hull Mass Production (SES) – 1968 Aerojet All-Welded Aluminum AALC JEFF(A) (ACV & SES) – 1977 Bell AALC JEFF(B) Controllable Bow Thrusters (ACV) – 1977 14

SOME OF THE MOST SIGNIFICANT DEVELOPMENTS 1978 to 2008
BHC Low-Pressure Responsive Skirts (ACV) – 1978 Bell BH-110 Medium Displacement Sidehulls (SES) – 1978 BLA Whole-Craft Design Synthesis Tools (ACV & SES) – 1978 BHC/HW Air-Cooled Diesel, Auto-Welded Structure for AP.1-88 (ACV) – 1982 Griffon Hovercraft Ltd starts World’s Largest Range of ACVs – 1982 LCAC Erosion Protected Propeller and Fan Blades (ACV) – 1984 Brodrene Aa Cored Composite Structures (SES) – 1986 BLA Compact Axial-Flow Water Jets (SES) – 1988 ABS Hovercraft Ltd M-10 with Advanced Composites (ACV) – 1994 BLA Deep Skirt (ACV) – 1995 BLA Wake-Adapted Shrouded Airscrews (ACV) – 2003 THIS CONTINUES THE LIST FOR THE NEXT 30 YEARS WHICH INCLUDES: THE BELL BH-110 SES WITH MEDIUM DISPLACEMENT SIDE HULLS THAT SET THE TREND FOR MOST SUBSEQUENT SES WORLD-WIDE, Slide change ………………………………………… THEN THE LOWER COST BHC AND HOVERWORK AIR-COOLED DIESEL & AUTOMATIC-WELDED MARINE STRUCTURE FOR THE AP.1-88 AND SUBSEQUENT DASH ACVs, Slide change …………………………………………… AND THEN THE LOW DRAG LCAC DEEP SKIRT AND SUBSEQUENT EVOLUTIONS BY BLA, Slide change …………………………………………….. AND THE LIST ALSO INCLUDES JAPAN’S OGASA-WARA TECHNO-SUPERLINER (SES), CURRENTLY THE WORLD’S LARGEST FAST FERRY, ALTHOUGH NOT CURRENTLY IN OPERATION.. I AM SURE I HAVE NOT LISTED ALL THE SIGNIFICANT DEVELOPMENTS, AND I AM SORRY IF I HAVE NOT MENTIONED OTHERS THAT YOU THINK SHOULD BE ON THE LIST. I KNOW I HAVE NOT INCLUDED HERE THE DEVELOPMENT OF HOVER BARGES, UTILITY CRAFT AND RECREATIONAL VEHICLES, BUT SOME ARE MENTIONED IN MY RINA PAPER. I HAVE ALSO NOT MENTIONED WING-IN-GROUND EFFECT OR OTHER FORMS OF AIR-ASSISTED CRAFT. MANY OF THESE HAVE POTENTIAL, BUT HAVE NOT YET BECOME WIDELY ACCEPTED. I WILL NOW SHOW YOU PHOTOS & VIDEO OF SOME OF THE EARLY CRAFT FOLLOWED BY THOSE THAT TOOK ADVANTAGE OF THESE DEVELOPMENTS . Japan’s Ogasawara 460-ft Techno-Superliner (SES) – 2005 Russia’s Murena E-Class Landing Craft (ACV) – 2005 IMAA Partial Air Cushion Catamaran, PACSCAT (SES) – 2008

VA1, (UK) THIS IS VICKERS ARMSTRONG’S FIRST ATTEMPT WITHOUT A SKIRT IN THIS WAS ANOTHER BRITISH FIRM HELPED BY HDL.

CC 1 AND 2, 1960 & 1961 (UK) THIS SHOWS THE EARLY PRODUCTS OF BRITAIN – NORMAN, THE CUSHION CRAFT 1 AND 2. BOTH ARE SHOWN WITHOUT PERIPHERAL SKIRTS, AND AGAIN A COMPANY HELPED BY HDL. THESE BRITISH CRAFT, LIKE THE SRN1, USED COCKERELL’S PERIPHERAL AIRJETS TO CONTAIN THE AIR CUSHION WITHOUT A SKIRT.

CC 2, 1961 (UK) HERE IS VIDEO OF THE CC2 OPERATING OVER LAND WITHOUT A SKIRT. THIS IS AT THE BEMBRIDGE AIRPORT ON THE ISLE OF WIGHT CLOSE TO WHERE MY FAMILY AND I USED TO LIVE.

SR-N2, 1961 (UK) First Integrated Lift & Propulsion & Maneuvering Control System
IT WAS NOT LONG BEFORE FLEXIBLE SKIRTS WERE TRIED. THE EVOLUTION OF THE SKIRT WAS THEN VERY RAPID, WITH NUMEROUS CONFIGURATIONS EVALUATED. SOME OF THESE EARLY SKIRTS WERE FAR MORE COMPLEX THAN THOSE IN USE TODAY. THIS SLIDE SHOWS THE SRN2 LAUNCHED IN 1961 THAT ALSO FEATURED THE FIRST INTEGRATED LIFT AND PROPULSION AND MANEUVERING CONTROL SYSTEM.

VICKERS VA-2, 1961 (UK) THIS SHOWS THE RESEARCH CRAFT VA-2 BY VICKERS.
THE VIDEO SHOWS HOW WELL SHE COULD OPERATE OVER ICE-LADEN WATERS.

VA3, 1962 (UK) First ACV Passenger Ferry
THIS IS ANOTHER VICKERS CRAFT, THE VA 3, WHICH, IN JULY 1962, WAS THE FIRST ACV TO ENTER COMMERCIAL FERRY SERVICE.

SR-N3, 1963 (UK) THIS SHOWS THE SRN3 IN 1963 WITH A SKIRT, BUT NO SPRAY SKIRT. SHE WAS BUILT AS A MILITARY TROOP AND VEHICLE CARRIER WITH A TOP SPEED OF 79 KNOTS. THIS WAS JUST 3 YEARS AFTER THE SRN1 WAS BUILT.

BELL SKMR-1, 1963 (USA) First ACV with Shrouded Props
THIS IS THE FIRST LARGE-SCALE PRODUCT OF THE UNITED STATES. IT IS THE 70-KNOT BELL HYDROSKIMMER-1. SHE ALSO WAS LAUNCHED IN 1963, BUT FIRST WITHOUT A SKIRT. AS MENTIONED EARLIER, IT ALSO FEATURED, FOR THE FIRST TIME ON AN ACV, THE MORE EFFICIENT SHROUDED PROPELLERS DERIVED FROM BELL’S TILT-WING AIRCRAFT PROGRAM.

BELL SKMR-1 (USA) A 4-FT SKIRT WAS THEN ADDED THAT ALLOWED FOR THE FIRST INTERFACE WITH THE DRY WELL OF AN AMPHIBIOUS LANDING SHIP.

HD1, 1963 (UK) With Inclined Finger Skirt
THIS IS THE HD1, OF COCKRELL’S HOVERCRAFT DEVELOPMENT LIMITED. IT FEATURED THE INCLINED FINGER SKIRT PATENTED BY DENYS BLISS IN 1962. IT TOOK BHC UNTIL 1964 TO REALIZE, AND ACCEPT, THAT THIS BAG & FINGER PLENUM CHAMBER CONCEPT WAS A FAR BETTER SOLUTION THAN THE PERIPHERAL JET SKIRT THAT WE AT SAUNDERS-ROE HAD BEEN STRUGGLING TO MAKE WORK SINCE 1960.

SR-N6 AND SR-N5, 1965 & 1964 (UK) THIS SHOWS THE BRITISH SR-N5 LEADING THE SRN6, BOTH IN CANADIAN COAST GUARD COLORS. THE SR-N5 WAS LAUNCHED IN 1963 AND THE N6, AS A STRETCH OF THE N5, IN 1965. BOTH CRAFT WERE DESIGNED PRIMARILY AS PASSENGER FERRIES, BUT MANY VERSIONS SAW DUTY IN MILITARY OR PARAMILITARY SERVICE. A TOTAL OF 65 OF THESE CRAFT WERE BUILT, PLUS ANOTHER 6 SRN-5s BUILT BY BELL AS U.S. MILITARY DERIVATIVES REFERRED TO AS SK5s OR PAC-Vs. THESE SAW DUTY IN VIETNAM AND ALSO AS U.S. COAST GUARD CRAFT IN THE MID TO LATE 1960’s. ONE SK5 WAS STATIONED AT FORT POINT SAN FRANCISCO THAT I GOT TO DRIVE IN 1969 ACROSS THE ROUGHEST PART OF SAN FRANCISCO BAY REFERRED TO AS THE POTATO PATCH. I MUST ADMIT THAT I FOUND IT TO BE A LOT EASIER DOING THIS IN A SAIL BOAT IN THE SAME AREA AND CONDITIONS, AND EVEN EASIER DRIVING A PHM HYDROFOIL THAT I WAS LUCKY ENOUGH TO DO OFF KEY WEST FLORIDA IN THE LATE 1980s.

SR-N5, 1964 (UK) With Peripheral Jet Skirt
THIS IS A VIDEO OF THE SR-N 5 OPERATING OVER WAVES. IT LOOKS EASY WHEN YOU KNOW WHAT YOU ARE DOING. WHEN FIRST LAUNCHED IN 1964, THE N5 HAD MUCH BIGGER STABILITY FINS AFT, SUCH THAT IF THE WIND WAS MUCH OVER 10 KNOTS IT COULD NOT TURN DOWNWIND. THIS WAS SOON FIXED WITH SMALLER FINS. ALSO, EARLIER IN 1963, WE FLIPPED A FREE-FLIGHT MODEL OF THE N5 WHEN CONDUCTING HIGH-SPEED TURNS ON A SMALL LAKE ON THE ISLE OF WIGHT. THIS WAS A MAJOR SHOCK TO THE COMPANY, AND WE WORKED AROUND THE CLOCK IN THE TOWING TANK TO DETERMINE THE CAUSE. WITH THE SUBSEQUENT ADOPTION OF THE HDL BAG-FINGER SKIRT BY BHC IN LATE 1964, THIS WAS NO LONGER A PROBLEM , IF COMBINED WITH CERTAIN OPERATIONAL RESTRICTIONS.

BHC SR-N4, 1968 (UK) With Bag-Finger Skirt
THIS IS THE SRN4 PASSENGER-CAR FERRY LAUNCHED IN 1968, MORE THAN 42 YEARS AGO. BY THE TIME IT WAS LAUNCHED, I HAD ALREADY LEFT SAUNDERS ROE AS I JOINED BELL, IN BUFFALO NEW YORK, IN JANUARY OF 1967. SIX OF THESE CRAFT WERE BUILT FOR SERVICE ACROSS THE ENGLISH CHANNEL. I WILL JUST LET YOU WATCH THIS NEXT VIDEO FOR FUN.

BHC SR-N4, 1968 (UK) ALL THE SRN4 DRIVER WANTED TO DO WAS TO STOP THE CAR SO THAT HE COULD GET A CLOSER LOOK. AS HE HAD NOT SEEN SUCH A NICE CAR BEFORE. IT WAS A GOOD COMMERCIAL FOR PEUGEOT.

BHC BH-7, 1969 (UK) WHEN THE BH-7 WAS BEING DESIGNED, THE BRITISH HOVERCRAFT CORPORATION WAS FORMED, AND CRAFT BUILT BY THEIR SAUNDERS-ROE DIVISION, ON THE ISLE OF WIGHT, HAD THEIR DESIGNATIONS CHANGED FROM SRN SERIES TO BH SERIES. THE BH-7, LIKE THE SR-N3, WAS DESIGNED FOR MILITARY DUTY.

BELL LACV-30, 1969 (USA/CANADA) Modular Construction for Transportability
THE LACV-30 WAS BUILT BY BELL IN CANADA IN THE LATE 1960s AND EARLY 70s. 26 WERE BUILT FOR SERVICE WITH THE U.S. ARMY AND WERE STATIONED AT FORT STORY VIRGINIA. THEY WERE OF MODULAR CONSTRUCTION FOR EASE OF TRANSPORTATION BY ROAD OR AIR. HOWEVER, THIS FEATURE WAS NEVER USED BY THE ARMY.

JEFF(A), 1977 (USA) First ACV with Welded Aluminum Structure
BASED ON THE SUCCESS OF THE SKIMMER 1 AND SK-5s, THE U.S. NAVY STARTED THE DEVELOPMENT OF AMPHIBIOUS ASSAULT LANDING CRAFT IN THE LATE 1960s. THIS RESULTED INITIALLY IN TWO CONTENDING PROTOTYPES LAUNCHED IN 1977 AND I WAS FORTUNET ENOUGH TO HAVE BEEN INVOLVED WITH THE DESIGN OFF BOTH. THE JEFF(A) BY AEROJET IS SHOWN HERE AND

JEFF(B), 1977 (USA) First ACV with Rotatable Bow Thrusters
THE JEFF (B) BY BELL IS SHOWN HERE. BOTH CRAFT WERE SUBJECTED TO EXTENSIVE TESTING THAT GENERATED A WEALTH OF SCIENTIFIC DATA FOR THE BENEFIT OF FUTURE DESIGNS SUCH AS LCAC AND THE CURRENT SSC. JEFF BENSON, JACK OFFUTT, BILL HARRY, DICK KENEFICK, MARTY FINK, AL KID, RAY ALLEN, PHIL SCHNEIDER, BILL WHITE AND MANY MORE FROM NAVSEA, NSWC CARDEROCK AND MY COMPANY WERE ALL HEAVILY INVOLVED IN THIS PROGRAM. MANY OF THESE GENTLEMEN ARE HERE TONIGHT.

BHC AP-188, 1982 (UK) Air-Cooled Diesel-Powered and Auto-Welded Aluminum Structure
THIS IS THE AIR-COOLED DIESEL-POWERED AP-188 DEVELOPED AS A JOINT EFFORT BETWEEN BHC AND HOVERWORK IN THE UK. THIS ALL-WELDED ALUMINUM CRAFT REPLACED THE ALL-RIVETED ALUMINUM GAS-TURBINE POWERED SR-N6 FOR THE SOUTH SEA TO ISLE OF WIGHT ROUTE WHICH HAD STARTED OPERATION IN 1965. THE AP1-88 WAS MUCH QUIETER AND MUCH MORE EFFICIENT THAN THE SR-N6.

LCAC, 1984 (USA) HERE IS THE U.S. NAVY’S LCAC OF WHICH 91 WERE BUILT, AND OF WHICH HAVE NOW BEEN TREATED TO A SERVICE-LIFE EXTENSION PROGRAM. ANOTHER 6 WERE BUILT FOR JAPAN.

GRIFFON-HOVERWORK 4000 TD (UK)
THIS SHOWS TWO CRAFT FROM GRIFFON IN THE UK WHO LAUNCHED THEIR FIRST CRAFT IN 1984. THEY CURRENTLY HAVE MORE THAN 150 DIESEL-ENGINED CRAFT IN SERVICE IN OVER 35 COUNTRIES WORLDWIDE.

POMORNIK, 1986 (ZUBR-CLASS USSR)
Click for Web Site THE FORMER SOVIET UNION, SINCE 1965, PRODUCED MORE MILITARY ACVs THAN ANY OTHER COUNTRY. THEIR LARGEST ACV IS THE 60-KNOT, 380-TON POMORNICK OR ZUBR-CLASS ACV FIRST LAUNCHED IN 1986. NINE OF THESE ZUBR-CLASS ACVs WERE BUILT AND USED BY THE MILITARY OF RUSSIA, THE UKRAINE AND GREECE. AT 187 FT IN LENGTH, THEY ARE THE BIGGEST ACVs IN THE WORLD BUT JUST TWO FEET LONGER THAN THE STRETCHED SR-N4s.

ABS M-10, 1994 (UK) THIS IS THE 50-KNOT ABS M-10, FIRST LAUNCHED IN 1994, WITH A HULL OF ADVANCED COMPOSITES. I AM NOT SURE HOW MANY WERE BUILT BUT, ACCORDING TO THE LATEST JANE’S, THEY HAVE SEEN SERVICE WITH THE SWEDISH COASTAL AUXILIARY, THE SRI LANKA NAVY AND HAVE PERFORMED COMMERICAL OPERATIONS IN BELGIUM. ONE WAS BUILT UNDER LICENSE BY KKrV IN SWEDEN. ANOTHER WAS BUILT UNDER LICENSE LAST YEAR BY THE U.S. FIRM EPS OF TITUSVILLE FLORIDA.

DASH 400, 1998 (UK) THIS BRINGS US TO THE DASH 400 WHICH IS A STRETCH OF THE AP-188. TWO OF THESE WERE BUILT UNDER LICENSE BY HIKE METAL OF WHEATLEY ONTARIO AND ARE IN SERVICE WITH THE CANADIAN COAST GUARD. VERY NOTICEABLE ARE THE TWO LARGE ROTATABLE BOW THRUSTERS FOR IMPROVED MANEUVERABILITY THAT ARE SIMILAR TO THOSE FIRST USED ON THE BELL JEFF (B).

DENNY D1 SES, 1961 (UK) WE NOW TURN TO SES.
52 YEARS AGO, ALL OF THE HOVERCRAFT ACTIVITY INVOLVED THE AMPHIBIOUS TYPE. HOWEVER, AL FORD IN THE UNITED STATES & DENNY BROTHERS IN SCOTLAND WERE SOON EXPLORING MORE EFFICIENT WAYS OF SEALING THE CUSHION OF A HOVERCRAFT. DENNY LAUNCHED THEIR FIRST EXPERIMENTAL SES SHOWN HERE IN MAY OF IT WAS BUILT OF WOOD, HAD A LENGTH-TO-BEAM RATIO OF 7, A TOP SPEED OF 17.6 KNOTS AND WAS CALLED THE D1.

DENNY D2 SES, 1962 (UK) First SES Passenger Ferry and First of GRP
BASED ON THIS EXPERIENCE, DENNY LAUNCHED IN 1962 THE FIRST SES PASSENGER FERRY, THE D2, SHOWN HERE. THIS WAS ALSO THE FIRST SES WITH GRP HULLS AND HAD A TOP SPEED OF 34 KNOTS.

HD1 CONVERTED TO SES, 1963 (UK)
IN 1963, COCKERELL’S HOVERCRAFT DEVELOPMENT LTD (HDL) CONVERTED THE D1 ACV TO AN SES, SHOWN HERE.

US NAVY XR-1 SES, 1963 (USA) First High-Speed SES
MEANWHILE IN THE USA, AL FORD AND HIS TEAM WERE FOCUSING ON HIGHER SPEEDS FOR MILITARY APPLICATIONS. IN 1963, THEY LAUNCHED THE 40-KNOT XR-1 EXPERIMENTAL REASEARCH CRAFT ON WHICH AL FORD AND BOB WILSON DID SIGNIFICANT WORK IN ADVANCING THE STATE OF THE ART IN HIGH-SPEED SES TECHNOLOGY. IN HER 20-YEAR LIFE, THIS CRAFT SAW FOUR MAJOR MODIFICATIONS BEFORE SHE WAS RETIRED AS THE XR-1E IN 1983.

US NAVY XR-1D SES, 1974 (USA) THIS SHOWS THE XR-1 IN SAN DIEGO AS THE XR-1D. WE NEARLY DESTROYED THIS BOAT IN 1978 DURING EXTREME SEA STRUCTURAL LOADS TEST IN THE CHESAPEAKE BAY. BUT SHE SURVIVED.

US NAVY XR-3 SES, 1967 (USA) TO PROVIDE FURTHER UNDERSTANDING OF SEAKEEPING AND STABILITY, THE DAVID TAYLOR MODEL BASIN LAUNCHED, IN 1967, THE XR-3. THE PRINCIPAL ENGINEERS AND TEST PILOTS ON THIS CRAFT INCLUDED BILL HARRY AND MARTY FINK. THIS WAS A PRELUDE TO A MAJOR COMMERCIAL AND MILITARY SES DEVELOPMENT IN THE U.S. LOOKING FOR A 3000-TON ASW FRIGATE AND A 20TH CENTURY YANKEE CLIPPER.

HM2 SES, 1968 (UK) BACK IN THE UK, HOVERMARINE HAD PICKED UP SES DEVELOPMENT AND, IN 1968, HAD LAUNCHED THE FIRST OF A VERY SUCCESSFUL SERIES OF GRP FERRIES AND WORKBOATS. OVER 100 OF THESE GRP CRAFT WERE BUILT AND OPERATED IN 28 DIFFERENT COUNTRIES IN SEVERAL DIFFERENT CONFIGURATIONS.

HM2 THIS SHOWS THE HM2 IN ITS FIREBOAT CONFIGURATION.

BELL SES 100B, 1972 THE 3KSES PROGRAM ALSO PRODUCED TWO TEST PLATFORMS, THE 100A AND THE 100B. THE 100B, SHOWN HERE, WAS LAUNCHED BY BELL IN ‘72 AND ACHIEVED A SPEED OF 89 KNOTS USING GAS TURBINES AND SURFACE-PIERCING PROPS. I WORKED ON THE DESIGN OF THIS BOAT WITH OTHERS INCLUDING ROB MOORE AND JOHN ALLISON IN 1967 AND 1968 IN BUFFALO NEW YORK.

AEROJET SES 100A, 1972 (USA) THE 100A WAS DESIGNED BY THE AEROJET GENERAL CORPORATION AND ACHIEVED A SPEED OF 76 KNOTS WITH WATERJET PROPULSION. I ALSO WORKED ON THIS PROGRAM FROM 1968 THROUGH THE LATE 1970s.

3KSES (USA) THIS SHOWS AN ARTIST’S DRAWING OF WHAT THE U.S. NAVY WAS AIMING AT DURING THE 1970s. IT IS THE 3KSES WITH A PROJECTED TOP SPEED OF 80 KNOTS. SEVERAL KEY PLAYERS IN THIS PROGRAM ARE ACTUALLY HERE TONIGHT . THEY INCLUDE AL. SKOLNICK, BILL WHITE, AL FORD, BOB WILSON, BOB ETTER, RAY ALLEN, BILL RICHARDSON, BEN SCHAUB &, I BELIEVE, BOB LAMB.

US NAVY XR-5 SES, 1973 (USA) MEANWHILE, AT DAVID TAYLOR, AL FORD AND HIS TEAM, INCLUDING BOB WILSON AND AL KID, ALSO I THINK BILL WHITE, WERE EXPLORING THE REDUCED POWERING BENEFITS OFFERED BY HIGH LENGTH-TO-BEAM BASED ON RESULTS OF TESTING THEIR XR-5, SHOWN HERE, WHICH THEY LAUNCHED IN 1973.

BELL-HALTER BH-110 SES, 1978 (USA) First Commercial SES in USA
BELL AEROSPACE TEXTRON TEAMED WITH HALTER MARINE AND PRODUCED, IN 1978, THE BH-110, SHOWN HERE, AS THE FIRST COMMERCIAL SES IN THE U.S. SIX OF THESE CRAFT WERE BUILT. THREE WERE ACQUIRED BY THE U.S. COAST GUARD AND OPERATED AS DRUG INTERDICTION CRAFT OUT OF KEY WEST, FLORIDA.

SES-200, 1982 (USA) ONE BH-110 WAS PURCHASED BY THE U.S. NAVY FOR TESTING AND THEN STRETCHED TO BECOME THE SES 200. JACK OFFUTT, OF NSWC CARDEROCK, HAD MUCH TO DO WITH THE MANY PHASES OF THIS PROGRAM. THE OTHER TWO BH-110s WERE OPERATED AS CREW BOATS. ALL THESE NEW SES BY BELL WERE OF A DIFFERENT BREED, FEATURING FULL-BODIED SIDEHULLS, WHICH SET THE BASIC TREND FOR MOST SUBSEQUENT SES HERE AND OVERSEAS.

CIRR 120P SES, 1987 (NORWAY) First Cored FRP SES
ALSO IN 1984, THE NORWEGIAN FIRMS OF CIRRUS AND BROAD REN OR LAUNCHED THE FIRST OF A SUCCESSFUL SERIES OF CORED FRP SES. THIS LED THE WAY TO SERIES PRODUCTION OF THE 50-KNOT 120P, SHOWN HERE, THAT WAS LAUNCHED IN 1988. BILL McFANN OF MDI, WHO IS HERE TONIGHT, PROVIDED SIGNIFICANT SUPPORT TO THIS DEVELOPMENT.

DERGACH SES, 1987 (USSR) Largest Military SES
THIS IS THE FORMER SOVIET NAVY’S DERGACH. IT IS THE LARGEST MILITARY SES TO DATE. SHE WAS COMMISSIONED IN THE SPRING OF 1990 AND HAS A DISPLACEMENT OF 650 TONS.

CORSAIR SES,1989 (GERMANY) Modular Construction including MTU Diesels Suspended in Modules from the Overhead IN ‘89, THE BLOHM & VOSS SHIPYARD IN HAMBURG GERMANY LAUNCHED THE 118-FT CORSAIR. THIS BOAT USES MODULAR CONSTRUCTION INCLUDING MTU DIESELS SUSPENDED IN MODULES FROM THE OVERHEAD FOR ISOLATING SHOCK AND VIBRATION. THE CORSAIR IS PROPELLED BY SURFACE-PIERCING PROPS AND HAS ALSO ACHIEVED SPEEDS OF OVER 50 KNOTS. GEORGE JENKINS & I WERE ONBOARD THIS CRAFT IN THE BALTIC WHEN IT WAS ARRESTED BY A DANISH COAST GUARD HELICOPTER FOR SPEEDING TOO CLOSE TO THEIR SHORE.

AGNES 200 SES, 1990 (FRANCE) DURING THE 1980s, THE FRENCH HAD SIGHTS ON SES AS A HELICOPTER PLATFORM AND EMBARKED UPON THE DEVELOPMENT OF AN ASW CORVETTE. THIS SHOWS THE AGNES 200 DURING HELICOPTER TRIALS.

AGNES 200 SES, 1990 (FRANCE) THIS SHOWS HER UNDERWAY.
THE CRAFT WAS OF WELDED ALUMINUM CONSTRUCTION AND HAD MANY UNIQUE FEATURES INCLUDING PRESSURE BALANCED END SEALS THAT WOULD MORE READILY TRACK THE SURFACE OF THE WATER AT HIGH SPEED. WE ACTUALLY HIRED THEIR CHIEF DESIGNER, WHO WORKED FOR US IN THE STATES FOR 10 YEARS. SOME OF YOU WILL REMEMBER PHILIPPE GOUBAULT.

SMYGE SES, 1991 (SWEDEN) IN 1991, THE SWEDISH SHIPYARD KKrV BUILT THE STEALTH TEST CRAFT “SMOOGA” FOR THE SWEDISH NAVY. SUBSEQUENT DESIGN AND COMPARATIVE STUDIES THAT WE COMPLETED FOR THEM AT BLA CONFIRMED THAT A MONHULL WOULD BE THE BEST SOLUTION FOR THEIR MISSION GOING FORWARD. THUS, THE VISBY PATROL BOAT WAS BORN.

OKSOY & ALTA-CLASS, 1993 (NORWAY) Mine Hunters and Sweepers
IN 1989, THE NORWEGIAN NAVY SIGNED A CONTRACT WITH THE NORWEGIAN YARD KVAERNER MANDAL TO BUILD NINE 350-TON MCM SES, SHOWN HERE, OF THE OKSOY & ALTA CLASS. ALL OF THESE VESSELS HAVE LIFT FANS THAT WE DESIGNED.

OKSOY SES, 1993 (NORWAY) THE FIRST BOAT WAS LAUNCHED IN 1993 AND WAS THE SUBJECT OF EXTENSIVE TRIALS.

P960 SES, 1997 (NORWAY) 55-knot Skjold Military Patrol SES
THIS IS THE NORWEGIAN 55-KNOT SKJOLD MILITARY PATROL SES FROM KVAERNER MANDAL (NOW UMOE MANDAL). SIX HAVE BEEN IN SERVICE SINCE 1999. THIS SES, AGAIN, FEATURES LIFT FANS THAT WE DESIGNED. I WILL SHOW UNDERWAY VIDEO OF THIS CRAFT A LITTLE LATER.

IMAA 1/3rd -Scale FLC Manned Model (UK) Partial Air Cushion Catamaran, PACSCAT (SES) Operating at High Speed in Scale SS4 Head Seas THIS IS A PHOTO OF ONE OF THE LATEST SES, THE MANNED MODEL OF THE LOW-COST PACSCAT DESIGNED AS A FAST LANDING CRAFT. THE PHOTO IS COURTESY OF JOHN LEWTHWAITE, THE INVENTOR, AND SHOWS THE MANNED-MODEL OPERATING IN HEAVY SEAS. AS A SIDE, YOU MIGHT BE INTERESTED TO KNOW THAT JOHN LEWTHWAITE AND I WORKED TOGETHER DURING THE EARLY 1960’s IN THE HYDRO OFFICE OF SAUNDERS ROE ON THE ISLE OF WIGHT.

PACSCAT 2010 (UK) Click for Web Source
THE LATEST SES IS A 30-m FULL-SCALE DEMONSTRATOR VERSION OF THE PACSCAT CONCEPT THAT WAS LAUNCHED BY QINETIG (KENETIC) IN THE UK IN SEPTEMBER OF 2009. IT HAS NOW COMPLETED ITS EVALUATION BY THE UK ROYAL MARINES OFF THE NORTH COAST OF DEVON.

JAPAN’S TSL-A140 OGASAWARA SES, 2005 Largest Fast Ferry of any kind
THIS BRINGS US TO THE LARGEST SES EVER BUILT, THE OGASA-WARA BUILT BY MITSUI IN JAPAN. IT IS A PASSENGER-CARGO VESSEL INTENDED FOR THE TRIP FROM TOKYO TO OGASA-WARA. IT HAS THE LARGEST ALUMINUM STRUCTURE OF ANY MARINE VESSEL TO DATE. AT A LENGTH OF 140 m, IT IS 72% LONGER THAN THE U.S. NAVY’S 3KSES, WHICH WAS DESIGNED IN THE LATE 70s BUT NEVER BUILT. FOLLOWING SUCCESSFUL SEA TRIALS IN LATE 2005, IT WAS ANNOUNCED THAT THE VESSEL WOULD NOT BE IMMEDIATELY OPERATED DUE TO FINANCIAL DIFFICULTIES. THERE HAS, OF COURSE, BEEN MANY MORE SIGNIFICANT VESSELS THAT WERE BUILT AND CONTRIBUTED TO THE TECHNOLOGY. THESE I HAVE NOT MENTIONED TODAY, BUT SOME ARE DISCUSSED IN MY RINA PAPER.

MORE RECENT TECHNOLOGY DEVELOPMENTS
CUSHION SEALS PROPULSION MANEUVERING CONTROL DESIGN SOFTWARE I WILL NOW DISCUSS OTHER RECENT ADVANCES MADE IN THE TECHNOLOGIES THAT ARE UNIQUE TO ACVs AND SES. THESE ARE THE ADVANCES THAT HAVE BEEN MADE TO FURTHER THE PROGRESS TOWARDS MEETING THE CHALLENGES THAT I MENTIONED EARLIER. TO SAVE TIME, I WILL NOT MENTION THE DEVELOPMENT WE HAVE ACCOMPLISHED WITH LIFT FANS. FOR THAT, YOU SHOULD READ MY RINA PAPER.

SKIRT SYSTEMS Cross-Section of JEFF Craft Skirts
THE FIRST, AND BY FAR THE MOST IMPORTANT, UNIQUE SYSTEM IS THE SKIRT OR FLEXIBLE SEAL SYSTEM. THIS IS THE PRINCIPAL FEATURE THAT HAS SET ACVs AND SES APART FROM OTHER CRAFT. CROSS SECTIONS OF TYPICAL SIDE AND BOW SKIRTS FOR AN ACV ARE SHOWN HERE. WHEN INFLATED BY THE ONBOARD FANS, THEY EXTEND IN THIS FORM ALL THE AWAY AROUND THE PERIPHERY OF THE CRAFT TO IMPEDE OUT FLOW OF AIR FROM THE CUSHION AND PROVIDE LIFT AND INHERENT PITCH, HEAVE, AND ROLL STABILITY TO THE CRAFT. THIS ALLOWS THE HARD STRUCTURE OF THE CRAFT TO RISE TO A HEIGHT THAT PROVIDES A USEFUL CLEARANCE FOR OPERATION AT SEA AND OVER LAND. SIDE SKIRT BOW SKIRT

DEEP SKIRT DESIGN IN THE MID 1990s, THE U.S. NAVY HAD AN EMERGING REQUIREMENT FOR SURF-ZONE MINE COUNTERMEASURES USING THE LCAC. THIS LEAD TO THE NEED FOR A DEEPER SKIRT, FEATURED IN THIS ILLUSTRATION, TO INCREASE FREEBOARD BY 2 FT. THIS WOULD REDUCE THE CHANCE OF SURF BREAKING OVER THE STERN AND DAMAGING THE PROPELLERS. THE CRAFT STILL HAD TO ENTER THE DRY WELL OF AN AMPHIB. SHIP AND THERE WAS A SERIOUS NEED TO REDUCE SKIRT MAINTENANCE. AS A RESULT, A SKIRT WAS DEVELOPED UNDER DIRECTION FROM NSWC PANAMA CITY THAT FEATURED A DOUBLE-BUBBLE OUTER SIDE BAG TO PRESERVE WELL DECK COMPATIBILITY AND BACK-TO-BACK SIDE FINGERS FOR ENHANCED ROLL STABILITY. THE CONCEPT WE DEVELOPED WAS DIFFERENT, BUT SHARED SOME FEATURES WITH THE LOOP PERICELL SKIRT THAT I HELPED DEVELOP FOR THE AEROJET JEFF(A) IN THE LATE 1960’s. THIS FEATURE ALLOWED US TO ELIMINATE THE LCAC’s LONGITUDINAL STABILITY KEEL, WHICH REDUCED BOTH DRAG AND THE HIGH MAINTENANCE THAT IT REQUIRED.

DEEP SKIRT DESIGN Subjected to Extensive Sub-Scale Test Prior to Committing to Full-Scale Prototyping AS PART OF THE DEVELOPMENT OF THE PREFERRED GEOMETRY, NSWC PANAMA CITY CONTRACTED MY COMPANY TO CONDUCT SEVERAL SERIES OF MODEL TESTS TO ASSESS DRAG, SEAKEEPING AND STABILITY. THE TOWING TESTS WERE CONDUCTED AT THE SAUNDERS-ROE FACILITY OF WESTLANDS ON THE ISLE OF WIGHT WHERE I SPENT MUCH OF MY EARLY DAYS. WE EVEN TESTED A TETHERED MODEL, WITH WAVES FROM ASTERN CREATED IN A RECREATIONAL WAVE POOL, IN PANAMA CITY FLORIDA. FROM THESE TESTS, IT WAS EVIDENT THAT WE HAD REDUCED DRAG, IMPROVED SEAKEEPING AND SIGNIFICANTLY REDUCED THE LIKELIHOOD OF SHIPPING WATER OVER THE STERN INTO THE PROPELLERS. BUT HOW WOULD THIS SKIRT BEHAVE FULL-SCALE? AND, IN PARTICULAR, WOULD IT STILL ALLOW THE CRAFT TO ENTER AND LEAVE THE WELL DECK OF AN AMPHIBIOUS LANDING SHIP. 69

Suspected that Fatigue was the Primary Failure Mode.
NOT ALL IS GOOD Material Delamination after 100 operating hours on the prototype skirt. Issue also showed up on the Canadian Coast Guard AP.1-88/400 and the Hoverspeed SR.N4 MKIII. All three craft used the same natural rubber material. WELL, IT DID FIT THE WELL, AS SUBSEQUENT OPERATIONAL EXPERIENCE CONFIRMED, AND INDEED IT DID REDUCE DRAG, IT DID IMPROVE RIDE QUALITY, AND IT DID REDUCE SKIRT MAINTENANCE, BUT NOT AS MUCH AS DESIRED. DESPITE THESE IMPROVEMENTS, IT WAS EVIDENT FROM “AT-SEA” OPERATIONS THAT TYPICAL FATIGUE DELAMINATION WAS STILL OCCURRING IN THE OUTER FACES OF THE FINGERS, AS SEEN ON OTHER CRAFT USING THE SAME NATURAL RUBBER-COATED MATERIAL. Suspected that Fatigue was the Primary Failure Mode.

NOT ALL IS GOOD FEA analysis of an inflated finger indicated Stress Concentrations and areas of Large Deformations. SUBSEQUENT FINITE ELEMENT STRUCTURAL ANALYSIS OF THE FINGERS, MANAGED BY BRIAN FORSTELL OF OUR OFFICE, SHOWED THAT THE FULL-SCALE DELAMINATION HAD OCCURRED IN AREAS ON THE FINGER THAT EXPERIENCED THE HIGHEST STRESS, OR DEFLECTION, UNDER LOAD. TO OUR KNOWLEDGE, NO ONE HAD LOOKED AT THIS BEFORE. Stress Map Deflection Map

Deflection Map before Modification Deflection Map after Modification
THINGS GET BETTER FEA analysis indicated that a modification of the Design & Lofting Process would correct this. THE RECOGNITION OF THIS CORRELATION WAS THEN TAKEN INTO ACCOUNT IN THE DESIGN OF A SECOND GENERATION SKIRT. HERE, A SLIGHT MODIFICATION OF THE DESIGN RESULTED IN A SIGNIFICANT REDUCTION IN STRESS CONCENTRATION, AS SEEN IN THIS COMPARISON. Deflection Map before Modification Deflection Map after Modification

SECOND & THIRD GENERATION DESIGNS
2nd Generation T-2000 Skirt had 440+ hours on original bow and side fingers. Stern corner and stern fingers replaced after approximately 300 hours. THE SECOND GENERATION SKIRT WAS ALSO MODEL TESTED, THIS TIME AT NSWC CARDEROCK, AND USED ON THE FINNISH NAVY’S 70-KNOT T-2000 COMBATANT ACV. FOR THIS NEW SKIRT, NO SERIOUS FATIGUE DELAMINATION OF THE BOW AND SIDE FINGERS WAS SEEN BEFORE 440 HOURS OF OPERATION, WHILE STERN FINGERS LASTED FOR MORE THAN 300 HOURS. BY COMPARISON, THE ORIGINAL LCAC FINGERS WERE LASTING ONLY 200 HOURS BEFORE REPLACEMENT. A THIRD GENERATION SKIRT WAS ALSO DESIGNED FOR AN ASIAN CLIENT AND ALSO TESTED AT CARDEROCK. THIS DESIGN WAS FABRICATED AND USED ON THE FULL-SCALE CRAFT WITH EVEN BETTER RESULTS.

SECOND & THIRD GENERATION DESIGNS
Head-Sea Operation in Sea-State 3 THIS SLIDE COMPARES SKIRT DRAG VERSUS SPEED FROM THE MODEL TESTS OF ALL THREE GENERATIONS OF SKIRT. THIS CLEARLY ILLUSTRATES THE SIGNIFICANT EXTENT TO WHICH EACH SUCCESSIVE DESIGN HAS REDUCED DRAG. THIS WORK HAS CONTINUED IN SUPPORT OF THE FOLLOW-ON LCAC – THE SHIP-TO-SHORE CONNECTOR. . Believe that Additional Performance Improvements are Possible

THE OVERALL POWERING CHALLENGE
Diminishing Transport Efficiency with Speed THE POWERING CHALLENGE Circle Q W.V P NOW, I HAVE JUST TALKED ABOUT DRAG, BUT BEFORE DISCUSSING THE LATEST ADVANCES IN PROPULSION FOR ACVs, I WILL SHOW YOU A FEW VIDEOS OF VESSELS OF DIFFERENT TYPES AND HOW THEY HAVE PROGRESSIVELY LESS CONTACT WITH THE WATER AND, THEREFORE, PROGRESSIVELY LESS DRAG. THIS FIRST CHART DEFINES THE OVERALL POWERING CHALLENGE. THIS IS A MODIFIED VERSION OF A CHART THAT I RECEIVED ORIGINALLY FROM JOHN HOYT OF NSWC CARDEROCK. IT IS BASED ON THE CIRCLE “Q” AND “K” RELATIONSHIPS MADE FAMOUS BY FROUDE IN THE LATE NINETEENTH CENTURY. IT COMPARES TRANSPORT EFFICIENCY VERSUS NON-DIMENSIONAL SPEED AND SHOWS THIS FOR A VERY WIDE RANGE OF VESSEL TYPES. THE CHALLENGE IS THAT, AS SPEED INCREASES, EFFICIENCY FALLS OFF RAPIDLY. THIS IS DUE TO A NUMBER OF FACTORS. THE MAIN FACTORS, OF COURSE, ARE THE RAPID INCREASE IN DRAG AND THE INHERENT LOSS OF THRUST WITH SPEED. OVER THE YEARS, THE INCREASE IN DRAG HAS BEEN OVERCOME PRIMARILY BY DISCONNECTING THE VESSEL FROM THE WATER, AS THE EARLY HOVERCRAFT INVENTORS TRIED TO DO, PARTICULARLY SIR CHRISTOPHER COCKERELL. WE ,THEREFORE, SEE ON THE CHART THESE ATTEMPTS WITH HYDROFOILS, SES, ACVS AND HYDROPLANES (EVEN WIGS) OCCUPYING THE BEST ON THE RIGHT-HAND SIDE OF THE CHART. SPEED (VOLUMETRIC FROUDE NUMBER) Circle K

TODAY’S SOLUTIONS 70-kt ACV 70-kt ACV 40-kt SEMI-SWATH 100-kt OFFSHORE
RACERS 40-kt SEMI-SWATH HOWEVER, AS WE DECOUPLE FROM THE WATER, SO WE FIND IT HARDER TO FIND EFFICIENT PROPULSORS TO DO AN ADEQUATE JOB. THIS CHART SHOWS THE STATE OF THE ART IN THIS REGARD. Slide change …..……………………………………………………………………………… FIRST IS A 40-KNOT SEMI-SWATH REPRESENTED BY THE WATERJET-PROPELLED AUSTAL FERRY FROM AUSTRALIA. SHE HAS DISPLACEMENT SIDE HULLS AND IS POWERED BY A HIGH-SPEED DIESEL PLANT. Slide change …………………..………………………………………………. NEXT IS THE 55-KNOT SKJOLD SES FROM UMOE MANDAL IN NORWAY. SHE IS ALSO WATERJET-PROPELLED AND IS POWERED BY GAS TURBINES AND DIESELS. Slide change……………………………………………………………………….. NEXT IS THE 70-KNOT GAS TURBINE, AIR-SCREW PROPELLED, T-2000 FINNISH NAVY COMBAT ACV. SHE WAS DESIGNED WITH HELP FROM BLA AND WAS BUILT BY AKER FINNYARDS. SHE CARRIES THE BLA DEEP SKIRT. Slide change …………………………………………….……………….. THEN WE HAVE 100-KNOT PLUS OFFSHORE RACERS PROPELLED BY SURFACE DRIVES. IN ROUGH WATER, MUCH TIME IS SPENT OUT OF THE WATER WITH LOW DRAG BUT WITH AN EXTREMELY ROUGH RIDE. Slide change ………………………………………………..…………… AND, FINALLY, HYDROPLANES OPERATING AT SPEEDS OVER 170 KNOTS, ALSO ON SURFACE DRIVES, BUT ALSO IN RELATIVELY CALM WATER. NOTE THAT THE ACV AND SES FARE WELL ON THIS BASIS. THIS IS BECAUSE OF THEIR RELATIVELY LOW DRAG AT HIGH SPEED. THUS, ANY IMPROVEMENT IN PROPULSIVE EFFICIENCY FOR ACVs AND SES COULD BE EXPECTED TO PROVIDE FOR SIGNIFICANT ADVANTAGE. 55-kt SES 170+-kt HYDROPLANES 76

DUCTED PROPULSORS Typically, designs are developed for free-stream conditions. Ignores Installation Effects. Full-scale trials experience indicates that these designs typically produce Significantly Less Thrust than expected. SO, THIS LEADS TO WHAT WE CAN DO WITH ACV PROPULSORS. ACVs TYPICALLY RELY ON AIR SCREWS TO PROVIDE THE MAJORITY OF THE CRAFT’S FORWARD THRUST. WHILE THIS ALLOWS AMPHIBIOUS CAPABILITY, IT LEADS TO LOW PROPULSIVE EFFICIENCY COMPARED TO MARINE SCREW OR LAND TRACTION PROPULSION. THIS NATURALLY HAS A BIG IMPACT ON CRAFT INSTALLED POWER AND COST DESPITE THE LOW DRAG OF A SKIRT. FREQUENTLY, TO SAVE COST, ACV DESIGNERS COLLABORATE WITH AIR-SCREW MANUFACTURERS AND ADAPT EXISTING AIRCRAFT PROPELLERS THAT HAVE BEEN OPTIMIZED FOR MUCH HIGHER SPEEDS. THIS APPROACH HAS GENERALLY BEEN SUCCESSFUL, ALTHOUGH, WHEN OPERATING IN A CONFIGURATION WITH FLOW BLOCKAGE, THEY MOST OFTEN PRODUCE FAR LESS THRUST THAN EXPECTED. HOWEVER, A FEW YEARS AGO, WE DESIGNED A CUSTOM DUCTED AIR SCREW CAPABLE OF EFFICIENTLY ABSORBING 50% MORE POWER THAN CAN BE ABSORBED BY A LCAC PROPELLER. FOR THIS, WE USED CFD TO OPTIMIZE BLADE SECTION SHAPE INCLUDING THE GEOMETRY OF THE DUCT AND STATOR VANES. UNLIKE PREVIOUS DESIGNS, HOWEVER, WHICH WERE DEVELOPED FOR BASICALLY CLEAR UNDISTURBED FREE-STREAM AIRCRAFT-FLIGHT-CONDITIONS, OUR NEW DESIGN WAS OPTIMIZED WITH THE CFD REPRESENTING ALL UPSTREAM BLOCKAGE FROM THE LCAC-TYPE SIDE STRUCTURES AND CARGO DECK.

TOOL VERIFICATION LCAC CFX Computational Model LCAC propulsor analyzed prior to starting new design. Checked against known performance. Results compared favorably. CFX for LCAC at 25 knots (Midway Station 7’6”) TO ESTABLISH VERIFICATION OF THE PROCEDURE, WE FIRST MODELED THE CURRENT LCAC PROPELLER, THE FULL-SCALE PERFORMANCE OF WHICH WAS KNOWN. THE RESULTS COMPARED VERY FAVORABLY.

AIR FLOW INTO PROPULSOR
View from Bow View from Aft AFTER THE CFD TOOL ARRIVED AT A SOLUTION, THE POST-PROCESSING OF THE DATA ALLOWED US TO VISUALIZE THE AIR-PARTICLE STREAM LINES. SHOWN HERE ARE THE PROPELLER INFLOW STREAM LINES AND HOW THEY ARE SIGNIFICANTLY AFFECTED BY THE SIDE STRUCTURE BEFORE ENTERING THE PROPULSOR. TO IGNORE THIS EFFECT IN PROPELLER DESIGN WOULD NOT BE GOOD. TO FURTHER CHECK THE APPROACH, WE TESTED A MODEL OF THE NEW DESIGN IN THE WIND TUNNEL AT THE UNIVERSITY OF MARYLAND. RESULTS, AGAIN, COMPARED WELL WITH THE PREDICTIONS, AS DISCUSSED IN MY PAPER. Leading Edge of Shroud

BOW THRUSTER NOZZLES Bow Thrusters are used on many modern ACV’s
Enhance Maneuverability Augment Thrust from Main Propulsors Provide Some Redundancy to Main Propulsors WE NOW COME TO BOW THRUSTERS, ANOTHER UNIQUE ACV FEATURE. THESE ARE USED TO PROVIDE ADDITIONAL MANEUVERING CONTROL AND ADDITIONAL PROPULSIVE THRUST. TYPICAL BOW THRUSTERS ARE SHOWN FORWARD ON THE SIDE STRUCTURES OF THE CRAFT IN THIS SLIDE. THE BOW THRUSTER EXPELS HIGH-VELOCITY AIR, USUALLY FROM A DEDICATED FAN, TO PRODUCE THRUST FROM A NOZZLE THAT CAN BE ROTATED ABOUT ITS VERTICAL AXIS. THEY WERE FIRST DEVELOPED FOR THE BELL JEFF(B) IN THE EARLY 1970’s.

BOW THRUSTER NOZZLES Typical Bow Thruster Nozzle Easy to Manufacture
Aerodynamically Inefficient Easy Bend versus Hard Bend Large Over-Turning Moment on Bearing THIS SHOWS A TYPICAL BOW THRUSTER, WHICH IS RELATIVELY EASY TO MANUFACTURE BUT IS VERY INEFFICIENT AERODYNAMICALLY. THIS IS PARTLY BECAUSE THE GEOMETRY OF THE BEND IS WHAT WE CALL A HARD BEND, OR HIGH-LOSS BEND. THIS IS CHARACTERIZED BY THE FIRST ILLUSTRATION INSERTED AT THE BOTTOM OF THIS SLIDE. WHAT IS BETTER IS AN EASY BEND, OR LOW-LOSS BEND, AS CHARACTERIZED BY THE SECOND ILLUSTRATION AT THE BOTTOM OF THE SLIDE. THE HARD BEND ALSO RESULTS IN A TALL BOW THRUSTER THAT CAUSES PROBLEMS WITH OVERTURNING MOMENTS ON THE ROTATIONAL BEARING.

BOW THRUSTER NOZZLES Low-Profile Bow Thruster
Aerodynamically Efficient Cascade Significant Reduction in “Over-Turning” Moment on Bearing Reduced Visual & Radar Signature Complex to Manufacture FOR THE DESIGN WE DID FOR THE FINNISH NAVY’S T-2000, WE REALIZED THAT WE COULD CREATE A SERIES OF EASY BENDS WITH A CASCADE OF NOZZLES AS SHOWN HERE. THIS RESULTED NOT ONLY IN A SAVINGS IN POWER, BUT PRODUCED A LESS VULNERABLE APPENDAGE. IT ALSO RESULTED IN A SIGNIFICANT REDUCTION IN OVER TURNING MOMENT ON THE BEARING, PLUS REDUCED VISUAL AND RADAR SIGNATURE, AL BE IT WITH A LITTLE MORE COMPLEXITY. THESE ATTRIBUTES WERE VERIFIED DURING FULL-SCALE TRIALS. Full-Scale Trials Verified Aerodynamic Efficiency

ACV DESIGN TOOL Designing With Respect to Cost
MY LAST TOPIC IS ACV DESIGN TOOLS. IN 1978, THE CANADIAN DEFENSE RESEARCH ESTABLISHMENT ATLANTIC CONTRACTED US TO DEVELOP A DESIGN SYNTHESIS TOOL FOR ACVs USING PHYSICS-BASED ALOGORITHMS . IN THE 33 YEARS SINCE THEN, THE TOOL HAS CONTINUALLY GROWN IN COMPLEXITY AND HAS BEEN ALMOST CONTINUOUSLY USED TO SUPPORT NUMEROUS ACV PROGRAMS, AT HOME AND OVERSEAS. WHAT HAS BEEN PARTICULARLY USEFUL WITH THIS TOOL IS NOT ONLY ITS ABILITY TO DESIGN, BUT IT’S ABILITY TO QUICKLY EXAMINE THE ACQUISITION OR LIFE-CYCLE COST OF A DESIGN. WE CAN THEN SHOW HOW THIS COST VARIES WITH OPERATIONAL REQUIREMENTS AND WITH THE SELECTION OF DIFFERENT SUBYSTEMS AND TECHNOLOGIES. THE EXAMPLE OF RESULTS YOU SEE HERE WAS GENERATED FOR THE FINNISH T-2000 ACV AND SHOWS COST VERSUS CRAFT LENGTH AND LENGTH-TO-BEAM RATIO. RELATIVE TO THE INITIAL SPEC. FOR THE CRAFT, WE WERE ABLE, ON THE BASIS OF THIS, TO RECOMMEND A MORE FAVORABLE CRAFT OF HIGHER BEAM AND DEEPER SKIRT WITH NO CHANGE IN OVERALL COST.

SUMMARY & THE WAY AHEAD NEW SKIRT NEW LIFT FANS NEW PROPULSORS
Lower drag, reduced powering, more reliable, less cost. Extra depth, improved seakeeping /overland operations. NEW LIFT FANS Higher efficiency, more compact & quieter. NEW PROPULSORS Higher power absorption, more efficient. NEW BOW THRUSTERS More efficient, less vulnerable, reduced loading. NEW SES Lower cost, more reliable PACSCAT solution. ACV & SES DESIGN & ASSESSMENT TOOL Reduced cost, easier to assess technology options. Easier to assess cost impact of operational requirements. WHAT’S LEFT Lighter weight systems, better skirt material, stability, ride, collision avoidance, less noise, improved RMA & lower cost. THIS BRINGS ME TO THE END OF THE PRESENTATION. AND, IN SUMMARY, WE HAVE REVIEWED THE EARLY HISTORY OF DEVELOPMENT AND HAVE SEEN IN THE LAST 15 YEARS OR SO: SKIRTS WITH SIGNIFICANTLY REDUCED DRAG AND IMPROVED RELIABILITY HAVING LESS OPERATING COST DUE TO BETTER DESIGN, ALTHOUGH FURTHER IMPROVEMENT WOULD BE GOOD. BECAUSE OF THEIR EXTRA DEPTH, SEAKEEPING AND OPERATION OVER LAND IS ALSO IMPROVED. WE HAVE ALSO SEEN MORE EFFICIENT, COMPACT AND QUIETER LIFT FANS. AND NEW PROPULSORS THAT ARE CAPABLE OF EFFICIENTLY ABSORBING HIGH POWER. MORE EFFICIENT AND LESS VULNERABLE BOW THRUSTERS HAVE BEEN DEVELOPED GIVING BETTER MANEUVERABILITY WITH LOWER LOADS FOR THEIR AZIMUTH BEARINGS. WE HAVE ALSO RECENTLY SEEN A NEW LOW-COST SES CALLED THE PACSCAT DEVELOPED IN THE UK. ALSO, ANALYTICAL ASSESSMENT TOOLS HAVE BEEN EXPANDED AND ARE AVAILABLE THAT CAN BE USED TO HELP SELECT AFFORDABLE TECHNOLOGIES AND TO ASSESS THE COST IMPACT OF OPERATIONAL REQUIREMENTS. SO THESE, TOGETHER, SHOULD SERVE US WELL FOR THE TIMELY USE OF ACV TECHNOLOGY IN SUPPORT OF FUTURE REQUIREMENTS. TECHNOLOGIES THAT COULD RESULT IN EVEN FURTHER IMPROVEMENTS INCLUDE: LIGHTER WEIGHT BUT LESS EXPENSIVE STRUCTURES AND SYSTEMS, MATERIAL FOR SKIRTS THAT WILL NOT WEAR OUT OR FAIL, AN IMPROVED UNDERSTANDING OF UNDERWAY DYNAMIC STABILITY, MORE FOCUS ON DESIGNING FOR IMPROVED RIDE COMFORT, SKIRTS AND SEALS THAT ACTUALLY TRACK THE WATER SURFACE TO REDUCE LEAKAGE WITH LITTLE DRAG, BETTER MANEUVERABILITY & COLLISION AVOIDANCE CAPABILITY, REDUCED AIRBORNE NOISE, AND A GENERAL IMPROVEMENT IN OVERALL RELIABILITY AND OPERATING COST. THAT CONCLUDES MY PRESENTATION. AND THANK YOU FOR YOUR ATTENTION. I HOPE YOU FOUND IT INTERESTING.

Questions? I WILL NOW ANSWER ANY QUESTIONS YOU MIGHT HAVE.
I CANNOT, HOWEVER, ANSWER QUESTIONS CONCERNING THE NAVY’S SHIP-TO-SHORE CONNECTOR BECAUSE OF ITS CURRENT COMPETITIVE PROCUREMENT. THANK YOU.

DAVID R. LAVIS BAND LAVIS DIVISION OF CDI MARINE

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DAVID R. LAVIS BAND LAVIS DIVISION OF CDI MARINE

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