500th Voith Water Tractor, First Of New Generation, Now Under Construction*
—Report A v a i l a b l e— Over the years, numerous experiments have taken place in ship towage. One concept, however, has remained unchanged, that being the Voith water tractor. This year the 500th Voith water tractor is under construction, which provides an ideal opportunity to reflect on what led to the development of this tug type and its ever increasing prominence within the towage industry.
The problems and risks involved in ship-handling are well known.
With the development of the Voith- Schneider propeller, it was possible to depart from traditional ideas, i.e., of having the screw and rudder aft, and to venture to design a system which initially takes into account the problems encountered in shiphandling.
The special characteristics of the Voith-Schneider propulsion system which created an effective solution to existing problems are reviewed, as follows: - The axis of rotation of the propeller is perpendicular to the thrust plane.
- Within this plane the thrust can be infinitely varied in magnitude and direction.
- The blade profiles are arranged parallel to the axis of rotation and are therefore untwisted along their entire length. Thus zero thrust is clearly defined when the blade pitch is nil.
- Propeller pitch and thus thrust are controlled in respect of magnitude and direction according to rectangular coordinates. By a combination of the two coordinates, thrust changes can pass quickly through zero without creating any extraneous thrust in undesired direction.
- Because of its vertical axis, the propeller position can be chosen to optimize the correlation with the hull in respect of a particular task.
- The VSP is extremely robust due to the very low rotational speed of the rotor.
The free arrangement of the Voith-Schneider propeller under the vessel was ruled out because of the possible problems of grounding, lateral contacts and the crossing of chains and towlines. These potential problems were, however, countered with a guard plate which protects the blades and at the same time acts as a nozzle plate.
It was now possible to arrange the propellers forward ahead of the center of rotation of the vessel, giving it an active front steering which is comparable to a car with frontwheel drive and steering. The tow- ing gear was shifted aft behind the center of rotation of the vessel and a stabilizing fin arranged under it.
Thus, the tractor principle came into being which still exists fundamentally unchanged today.
The introduction of the Voith water tractor in ship-handling service proved to be a significant step toward improving ship safety. The first vessel of a new generation, now under construction in Antwerp, will be the 500th Voith water tractor to be built and in the 35-year history of this type of vessel, operational in about 100 ports around the world.
For further information and a free copy of the article on the 500th Voith water tractor Circle 46 on Reader Service Card *The above article is taken from an essay, "500th Voith Water Tractor—A Brief Review," by Dipl.-Ing. U. Sturmhofel, project manager in the Marine Engineering Division at J.M. Voith GmbH, Heidenheim.
Other stories from January 1989 issue
- Northwest Marine Services Named Distributor Of Hamilton Marine Jets page: 5
- TOURIST SUBMARINES MARK ENTRANCE INTO NEW ERA FOR PASSENGER VESSEL INDUSTRY page: 6
- ZF Offers Wide Range Of Marine Gears For Workboats/High-Speed Craft page: 6
- 500th Voith Water Tractor, First Of New Generation, Now Under Construction* page: 7
- Tax Corrections Act Offers Good News To Domestic Operators page: 8
- Texaco Marine Services Names Gaffney President, Chief Operating Officer page: 9
- Supply Vessel Overhauled By Homeport Marine page: 9
- CRUISE SHIPPING 89 page: 10
- A.G.M.A. Elects Haley To Serve Three-Year Term On Board Of Directors page: 11
- 1989 NAPVO ANNUAL CONVENTION page: 12
- NAPVO Appoints Lauridsen Technical Consultant page: 12
- Atlantic Marine To Build Caterpillar-Powered Longliner Processor page: 13
- Wartsila-Turku Delivers Barge Carrier To USSR page: 13
- A LETTER FROM THE PRESIDENT OF THE NATIONAL ASSOCIATION OF PASSENGER VESSEL OWNERS page: 14
- Hornblower Dining Yachts Contracts Trinity Marine Group To Build West Coast's Largest Diner Boat page: 14
- Seaward Offers 105-Page Technical Manual On Marine Fendering Systems page: 14
- POTENTIAL FOR SIGNIFICANT GROWTH FORESEEN IN EXPANDING CRUISE SHIPPING INDUSTRY page: 15
- OUTSTANDING PASSENGER VESSELS OF 1988 page: 16
- New Rope Specification Sheet Available From American Manufacturing page: 27
- Alfa-Laval's Nirex Distiller And New Ice Marine Are Ideally Suited For Trawlers & Variety Of Small Vessels page: 28
- 315-Passenger Boat Delivered By Leevac page: 29
- Aeroquip Offers New Cargo Control Products Bulletin page: 29
- MagneTek Consolidates M i l i t a r y Business Efforts page: 32
- Letter Of Intent Signed By SPD To Acquire Dyncorp Unit page: 32
- First Of 39 Hopper Barges Launched At Reactivated Equitable Shipyards page: 33
- Crowley Maritime Names Sean G. Burke President, Atlantic Division page: 34
- E.H. Wachs Introduces N e w Model HPS-15 Hydrostatic Power Supply page: 35
- Wartsila Launches Baltic Cruise Ferry For V i k i n g Line page: 35
- Schichau Seebeckwerft Delivers Gas Carrier page: 36
- 1989 SNAME Meeting To Feature Diversified Technical Papers— Small Craft To Icebreakers, CAD/CAM To Instrumentation page: 38
- Trinity Marine Group Awarded $5-Million Contract To Build Two Washington State Ferries page: 38
- Sophisticated Cableship Launched At Swan Hunter's Wallsend Yard page: 41
- Sohio Oil, Subsidiary Of BP America, Makes West Coast Acquisitions page: 41
- Service Marine—A Full Service Yard For The Passenger Vessel Market page: 42
- Comsat To Provide Low-Cost Standard-C Messaging Service page: 42
- Fjellstrand Delivers High-Speed Catamarans 'Sea Cat' And 'Jetcat' page: 43
- Innovative Propulsion System From Krupp MaK Offers Smooth, Economic Service For Passenger Ships page: 44
- TFC Corporation Offers Full Line Of Trash Compactors To Meet New Annex V/MARPOL Rules page: 44
- Pictou Industries Completes Third Enlargement Of Crandall R a i l w a y Drydock page: 46
- Jamesbury Offers N e w Compact Corrosion-Resistant Actuators page: 50
- Krupp Atlas Elektronik Introduces Atlas 8630 VTC Radar Designed For Vessel Traffic Control Applications page: 53
- Understanding Marine Rope Specifications Increases Safety And Cordage Life page: 53
- Schottel Pump-Jets Allow Passenger Boat To Operate Even In Shallow Water page: 54
- Hopeman Brothers Named U.S. Representative For IMAC page: 55
- Universal Tankships Installs NTC Ship Manager Software System page: 55
- A N e w Source For CP Propeller And Control System Service page: 58
- Inspection Service Founded To Meet N e w Offshore Platform Inspection Requirements page: 58
- Quality Shipbuilders Changes Name And Revamps Structure; Jack Edwards Named President page: 58
- Morrison-Knudsen Appointed EMD Distributor In 17-State Area And All Of Caribbean page: 58
- SWDiesel-Powered 'Arctic Storm' Is Largest U.S. Factory Trawler page: 59
- Marinette Marine Completes Yard Patrol Boat Contract page: 59