PRELIMINARY DESIGN OF PROTOTYPE PASSENGER TRIMARAN FOR ISLANDS CONNECTION Wolter R. Hetharia Department of Naval Architecture, Faculty of Engineering, Pattimura University Ambon, Mollucas, Indonesia. e-mail hethariawr@yahoo.com ABSTRACT Problems of marine transportation in Eastern Indonesia Waters, consist of many small islands, were evaluated. This is due to the existence of rough sea nature at certain periods of the year which affect the operation of monohull ships (capsize, uncomforted ridding, slamming, seasickness, trip delay, etc). Besides, the lack of infrastructures in small islands (seaports, bunkers, and other facilities) and island topography (mobile seaport and small number of passenger) results in some difficulties of inter-island transportation. The emerging of Trimaran boats, which were designed and operated in many places in the world, showed a great performance in rough seas, especially for passenger transports. However, the implementation of those boats could not be applied directly to these regions where a special design should be introduced which results in a special kind of Passenger Trimaran. The design concept will be applied at preliminary design phase then, experimental works on models will be conducted to determine boat performance of powering and sea keeping. Some design criterions will be applied to determine feasibility of designed boat to be applied as prototype. The results of design will confirm and determine an optimal dimensions and configurations of the designed passenger Trimaran boat. Keywords : Trimaran Design, Design Criteria, Experimental Works. Deift University of Technology Ship Hydromechanics Laboratory Library 2628 CD Deift Mekelweg 2 Phone: +31 (0)15 2786873 E-mail: Q.w.deheer tudelft.nl
1. INTRODUCTION 1.1. Background The global marine transportation still hold an important role in supporting development of a country. Particularly, for the Archipelago Countries in The Pacific Region, marine transportation have a great contribution in connecting many small islands within the country as well as outside the countries. People in those islands mostly occupy the shore area where the main activity is mainly related to the sea and the movement of people to other islands is high. Mollucas Waters as well as parts of Eastern Indonesia, lie in the West Pacific Rim, consist of many big and small islands where marine transportation is still absolutely required. The marine transportation activities in those cluster islands had been conducted due to the development of the area as well as human needs in any aspects. Many efforts had been carried-out to fulfill the need of marine transportation by constructing or supplying new boats. The development of transportation sector is increasing by the existence of area development. Besides, some marine activities are still running such as fishing and marine tourism where these tasks absolutely need boats and other supporting infrastructures. So far, the operation of the boats is running well for the existing conditions. The main trip for the big islands with the existing seaports is occupied by local government or private shipping companies by steel, FRP or wooden medium monohull ships. For many small islands, the transportation is fulfilled by small wooden or small fast FRP monohull boats. Those boats operations, in fact, were followed by some real existing obstacles. The main obstacles founded such as : sea nature conditions, small islands topography, lack of infrastructures in small islands and the existence of monohull boats it selves. Sea nature conditions cause a rough seas which is difficult for boats' journey. Island topography cause the natural seaport may move to the front or back of the island to avoid the big waves in shore, besides the number of passenger are so small. In addition, on the small islands. there are no fixed seaport and other supporting infrastructures; so the trip for small islands may not be occupied by medium or big boats but only possible for small ones. A basic obstacle comes from the operation of monohull boat with a low performance in rough seas.
The Rough seas conditions, with their characteristics, exist almost each period of the year caused by the wind blow from east, west, north or south directions. This may cause the big waves for the open sea on this waters. In fact, the safe journey is in the back of the islands of wind direction, but this may not be avoided for the full journey may not always in the back of the islands. The obstacles mentioned above may cause problems faced by the operation of the existing monohull boats, such as The big waves conditions causes u Marine accidents I boat capsized u Slamming effects on boat u u Uncomfortable boat ridding Seasickness and trip delay This problems exist each year in operating the monohull boats. Some events had been recorded for marine accident / boat capsized each year for the rough seas. Meanwhile, seasickness and uncomfortable ridding are existing each journey even for the small waves. The lack of infrastructure causes: u Boat own-handling / own facilities (fuel, fresh water, accommodation, etc..) u Special boat landing on the shore. Island topography causes: u u Mobile seaport thus, special landing for boats Small number of passenger thus, the journey may not be occupied by medium or big ships but possible for small boats Some efforts had been done by local institutions by launching big monohull ships or catamaran, but this work can not touch all small islands connection for the lack of seaport, infrastructure, small number of passenger. The sea conditions as well as islands topography still become the main problem for small islands connection in this region for years. The development of naval architecture in the last decade showed a significant level by the existence of new innovations contributed to some naval aspects. This development, in fact, affected in a great changing in naval architecture and marine engineering. A radical changing existed in hull modifications which produced some multi-hull ships like twin hull (catamaran), triple hull (Trimaran) as well as pentamaran. This significant changing give a modern principle of ship operation : better, faster and safer.
The development of multi-hull ships showed a great performance (compared to monohull) in rough seas in many parts of the world. This was indicated by the operating of Catamaran / SWATH and Trimaran, meanwhile, a special research for Pentamaran is still undergoing. In fact, in the last few years Trimaran showed a great performance by the existence of RV. Triton (Naval Ship) by British Government as well as MV. Triumphant (Passenger Boat) by Australian Government. Meanwhile the new products of Trimaran are going increase to fulfill a great market demanding all over the world. Those Trimaran ships. in fact, are modified from some traditional canoes (with two outriggers) operated in Pacific Regions. This traditional canoes it selves showed a greater performance at rough seas, but limited for some purposes; meanwhile those modern Trimaran showed a greater performance in early operation and growing up for market demanding and special tasks. Those boats, however, may not be applied directly for small islands connection, for the reasons of: the ships are bigger, need special port for landing, need many passengers, etc. From this point, some considerations of design should be taken into account for design procedures. The design procedures should be based on the design aspects to overcome the problems for small island connecting. This may resulted in a modified type of Trimaran that can be applied for island connection. 1.2. Problems Identification The problems mentioned earlier is showed in the following Figure 1.1. 1.3. Aim and Purposes: o To achieve a result of design of prototype passenger Trimaran for island connecting. u The result of design to be applied further for island transportation 1.4. Target and Contributions: Target: Development of means of marine transportation in archipelago regions Contributions: Ship owners / Shipping Companies, Shipyards, Related Institutions
ISLANDS CONNECTING MARITIME TRANSPORTS FACTS: INFRASTRtJC- BOAT: NATURE: TOPOGRAPHY: TURE: MONOH ULL ROUGH SEAS, MOBILE SEA - NO SUPPORT WAVES PORT, SMALL PASSENGERS y - SHIP OWN- HANDLING - SPECIAL LANDING P R O E M S -SHIP CAPSIZED -SLAMMING EFFECTS -UNCOMFORTED RIDDING -UNCONTINUOUS/DELAY -SPECIAL LANDING - SMALL BOATS SOL UT t ON S: JTEW TYPE OF BOAT SHIP 'YSTEM MULTIHULL (UMA RAN) SMALL BOAT y PRODUCT y P R O T O T Y P E SEA TRIAL Fig. 1.1 Problem Identification for Islands Transportation
EORET1CAL BACKGROUND 2.1. Development of Multihull Ships. Multihull ships are widely used for : Catamaran, Semi submersible Catamaran I SWATH, Wave piercing Catamaran, and Trimaran. Meanwhile, Pentamaran and TRIS WACH are still developed. Multihull ships are kind of special displacement ships where their development in the last time is revolutionary. Their application are mostly for passenger and naval ships. The development of these ships are fully based on an intensively research to fulfill their technical operation aspects. Beside a modification for hull form, some investigations are made for propulsion systems, materials, interior, etc. The Trimaran ships, used in many parts of the world, are basically a duplicate of small pacific Trimaran canoes (with two outriggers) where, in fact, are small Trimaran. Those canoes are still widely used by local fishermen in Mollucas Waters (West Pacific Rim). A big size of this boats are used for catching tuna fish in South West Pacific Ocean where those boats show a great performance in rough seas. Advantage of Multihull Ships. The advantage of a kind of ship is relative to others where this is related to a mission of the ship. A real difference may be showed when a ship with the same mission and size but the difference lay on the hull form. Generally the advantage of multihull compared to monohull (Warship Technology 2000, 2001; The Naval Architect 2000; 2001; Ship and Boat International 2001, 2002; Marine Technology, 1997; 1999; 2000) are A large space due to a wide range of hulls, may be suitably applied for passenger, naval boats, aircraft carrier or special cargo. > A great performance ri rough seas, may operate on higher sea state > A higher stability value, higher GM > A great level of comfort > Special for Trimaran, Effective Horsepower is lower Trimaran Compared to catamaran, the appearance of Trimaran are still new, yet their applications are considered spectacularly for their best performance. The appearance of RV. Triton (DERA I Defense Evaluation & Research Agency, British Government) and Triumphant (North West Bay Ships. Australia) showed a successful work of Trimaran.
Some advantages arise from the operation of the existence Trimaran u They have long slender and highly efficient center hull which contains all drive train machinery and provide increased performance and fuel efficiency u They have superior sea keeping abilities than monohulls in very rough weather u Their configuration allows large deck areas to a catamaran u They provide a striking and visually different design u They produce an exceptionally low wash and wake u Their triple hull arrangements offer an inherent safety advantage in that the side hulls will support the vessel should entire center hull be fully flooded. C. Trimaran Fishing Boats A bigger kinds of Trimaran boats operated in South West Pacific Ocean were built and operated by local Philippines Fishermen regarded as Trimaran Fishing Boat. A slender monohull in the center equipped by two outriggers make this boat fully regarded as Trimaran. The task of those boats is catching Tuna Fish and as fish collector. The small boat (7 GT, inboard engine) but, had improved a greater performance in Pacific Rough Seas and still applied nowadays. Besides, the small fishing boats designed and built by the writer which were : Gillnet 1,5 GT funded by Local Service of Marine Affairs (Hetharia, 2001) used for local fishermen, Tuna Multipurpose 2,5 GT funded by Department of National Education used for local fishermen (Hetharia, 2003) and Small Multipurpose Fishing Boat 4 GT funded by Minister of Research and Technology (Hetharia, 2005) for research purpose. Those boats had operated successfully and showed a better performance at Central Mollucas Waters where in fact, those are small Trimaran boats. 2.2 Passenger Trimaran Boat Design. A. Design Concept. The design is initiated by introducing a mission requirements of boat. The boat will be passenger type with a certain luggage. Mission of the boat are: u To be operated in calm and rough sea conditions (at certain sea state level) which reduce slamming effect, uncomforted ridding and trip delay. u To have own-handling facilities and special beach landing facility. u To have a rational size which is small boat.
The essence of this research is : the selection of boat geometry, dimensions, lay-out and systems. Rules and regulations for passenger will be applied in designing including space, comfort, safety, seaworthiness. etc. In addition, proper arrangement of room lay-out and boat systems should be fulfilled (Tagart, 1980; Watson, 1998; Schneekluth, 1987). Trial and Error Method (Spiral Design) will be applied in this new design virtually for this new kind of boat (Taggart, 1980; Lamb, 1969; Watson, 1998). This method, consist of four design phases and some design parameters, runs for several iteration stages where the design parameters will be evaluated and corrected. The work of research end up with preliminary design stage. The design parameters include : Mission Requirements, Arrangements, Principal Dimensions, Lines & Body Plan, Hydrostatics & Bonjean, Floodable Length & Freeboard, Structure, Powering, Lightship Weight Estimate, Capacities Trim & Intact Stability, Damaged Stability, Cost Estimates, Hydrodynamics B. Design Parameters of Boat Mission Requirements u To be operated in roughs sea condition (at certain sea state level) which reduce slamming effect, uncomforted ridding and trip delay. u To have own-handling facilities and special beach landing facility. u To have a rational size which is small boat u Additional parameters to be introduced into input design are number of passenger, speed, distance and endurance. General Arrangement (Hull & Machinery) Some criterions introduced for general arrangement of the designed boat: Hull Lay-out : Three Hull Bodies (Center body and 2 Outer bodies / Outriggers). High speed boat (Sea Jet Trimaran). Hull type for wave cut, bow type for wave cut. Two upper wing connectors to connect two outer bodies. Center body closed (equipped by doors, windows and air intake). Front door for main entrance and exit. Center body: Aircraft-like with small beam for displacement waterlines and wider beam upper part for rooms accommodation.
Outer bodies : 2 Slender Curved bodies as outriggers Spaces : Passenger Room, Pilot Room. Luggage Room, Engine Room, Oil Tanks, Fresh Water Tanks, General Stores, Cargo Store and Toilet. Passenger accommodation: Seats at main deck and Pilot room at upper raised deck Prime Mover : In-board engine, twin engine, twin screw propeller with high revolution Boat Systems : Lightning, communication, air regulator, doors and landing facilities. Principal Dimensions, Ship Lines, Body Plan Principal dimensions include : Length Between Perpendiculars LBP, Length of Waterline LWL, Length Overall LOA, Breadth of Waterline BWL, Breadth of Boat B, Breadth Overall BOA, Draft T, Deck Height D, Length of outer body LOUT, Breadth of outer body, BOUT Lines & body plans are constructed based on principal dimensions and general arrangements of boat. Hydrostatics Computation of hydrostatics parameters followed by curves, includes : SWL, XF, VCB, LCB, BML, BMT, V, A, C, CM, C, Cw, etc. Computation and drawing curves of Bonjean. Floodable Length & Freeboard Floodable length is adjusted to the computations and lay-out of boats rooms and compartments. Freeboard f= DT may be suited to boat dimensions and reserve buoyancy. Structure Boat structure may be designed to ensure boat strength. The choice of materials may be considered to the easiness to obtain material locally. Fiberglass Reinforced Plastic (FRP) may be main choice for the boat. Powering Estimated BHP to reach required speed. Total Resistance and EHP may be achieved from Towing Tank prediction. Selection of prime mover and propulsion systems include In-board engine, Twin engine, High speed engine, Steering systems, Ruder systems. Lightship Weight Estimate This boat components consist of : Boat light weight (LWT) and dead weight (DWT). Total boat weight may be adjusted to displacement. Besides, determination of LCG, VCG and TCG should be adjusted to LCB. VCB and TCB. Estimating may be required for empty and full conditions of the boat.
Capacities, Trim & Intact Stability These parameters include : Intact stability (empty and full conditions), Metacentre height (GM), GZ curve. Capacities include : passenger space, engine, steering, storage rooms, tanks, etc. Boat trim computations for empty and full conditions and Tonnage measurements. Damaged Stability Stability when damaged includes : reserve buoyancy, draft and boat conditions when damage. Reserve buoyancy and dimensions of compartments will be considered during design phase. Cost Estimates Total cost for boat : Initial investment (boat cost, initial operations), Income, Profit, BEP and Required Freight Rate. I. Sea keeping. Sea keeping components of the boat will be determined from models experiment, includes Motions : Rolling, Heaving and Pitching Periods. Boat behaves at rough seas and Speed Loss Towing Tank Prediction from boat modeling for several levels of sea state. C. Design Criteria. Some genera! design criterions are introduced for this design purpose: Mission requirements are implied to design boat to achieve dimensions and architect of the boat. Dimensions of boat may fulfill space required by of passengers and other spaces. Hull form of boat may satisfy lower resistance and prime mover selection may ensure the lower power at the required speed. Structure of boat may ensure the working stresses acting on the boat Cost parameter is required to determine Required Freight Rate Other design parameters satisfy all requirements include rules and regulations applied for the boat. Stability of the boat will be high priority to satisfy the operation of boat Sea keeping characteristics are required as control parameter to determine the boat may be applied as prototype.
3. RESEARCH IMPLEMENTATION 3.1 Scope of the Works Scope of the research work includes: Preliminarily Design of Prototype Passenger Trimaran boat. Boat components include : Type, Size and Systems of boat are presented in blue prints. Experimental works on modeling to select boat best dimensions. 3.2. Phase of the Work Phase of the research implementation includes Design Phase: Input data required in designing such as : number of passenger, crew, cargo / luggage, accommodation, trip-network, distance, speed, endurance, number and type of rooms, engine, wave and beach characteristics. The characteristic of material required to build the boat will be considered. Design of the boat should be executed with respect to design concept and parameters. The optimization of boat design will be obtained by evaluating the priority of design parameters and executed by an iteration process. The design output, then will be represented in form of blue prints to facilitate the construction phase of modeling. Experimental Phase: Experimental phase will be applied for the parameters of resistance, EHP and motions of boat. This job will be executed by testing boat modeling at towing tank. Rules and regulations of experiment and result to predict full-scale boat will be fulfilled to achieve the real value. Some experimental works may be repeated in order to find best performance of boat from resistance and sea keeping point of view Analyzing Phase This phase will be done to analyze design results to determine feasibility of boat operation. Sea keeping characteristic will be applied as control parameter in determining the boat to be applied as prototype. Report Phase Report phase is the last step of the whole works n this research.
Process. A. Preliminarily Design The design process is starting with the concept of design and input design parameters such as o Nature of the sea : wave and wind parameters, beach characteristics o Boat Trip o Number of Passenger : length, ports locations, trip network. : 40 persons (estimated) o Number of Crew 8 persons (estimated) o Cruising Speed : 30 knots (estimated) o Structure : Fiberglass Reinforced Plastic (FRP). o Other input parameters : endurance, luggage, consumptions, etc. The design continue with determining general arrangements of the boat, includes boat type, size, geometry, rooms / spaces arrangements, lay-out and systems. Rules and regulations are applied to adjust those requirements. Geometry of boat's hull is developed mainly to overcome sea characters in rough conditions. This is a new design concept for a small Trimaran boat as introduced in Fig. I. Boat dimensions are determined as first approach followed by lines and body plans. Dimensions at this stage, however, may not be fixed where it may be changed after some iterations process of design as well as experimental modeling. Computation of hydrostatic parameters and Bonjean based on lines plan followed by drawing their curves. Variables such as : floodable length, freeboard and reserve buoyancy may be also computed based on lines plan. Structure of boat consists of main structures and other structure components will be designed at initial design stage and will be revised at each step of iteration based on the real design load applied on the boat. Ship weight estimated then, is computed based on boat components (Light Weight and Dead Weight). This parameter is then compared to weight displacement of the boat. Capacities of room & tanks, stability (intact & damaged) and trim are computed based on boat geometry and weight components. Cost of the boat is estimated based on : component of materials, constructing cost, initial operations, income, profit, BEP and RFR.
Fig.1. New Design Concept of Passenger Trimaran Fast Boat
Determination of boat power (BHP) is done based on experimental work where from here total resistance (RT) and effective power (EHP) will be achieved; meanwhile, brake horsepower (BHP) is computed based on selected screw-propellers. Type and size of prime mover will be evaluated and selected. Rules and regulations concerning experiment work and predicting result for full-scale boat will be applied for this work. Parameters of sickening at this stage will be determined by experimental works based on boat geometry and input parameters. Experiment of boat mode! at the towing tank is executed to define boat characteristic (motions) at rough sea (pitching. heaving and rolling). Rules and regulations concerning experiment work and predicting results for fullscale boat will be applied for this work. Determination of whether or not the boat may be judged to be optimum for design point of view will be based on aspects of sea keeping characteristics (boat motions) and minimum resistance and BHP which is adjusted to boat geometry, layout and systems. Motions of boat (Rolling, Heaving, Pitching) are established according to rules and regulations applied for passenger boat. Experiment of models will also established the ability of boat to be operated at rough seas condition. Operation of full-scale boat at may be determined at sea state level from results of model. If this decision may not be achieved, then, the design process will be continued by iteration process to get the final target. If this design process may be fulfilled then, the final blue print and report may be finished. The full research implementation consist of design process and experimental works may be seen at next Figure 2.
START INPUT: MISSION REQUIREMENTS, DESIGN PARAMETERS GENERAL ARRANGEMENTS : SELECTION BOAT TYPE SIZE. SPACE, GEOMETRY, LAY-OUT & SYSTEMS RULES FOR SPACE, LAY-OUT, SYSTEMS BOAT TYPE : NEW DESIGN $ PRINCIPAL DIMENSIONS : OBTAIN FROM GENERAL ARRANGEMENTS LINES & BODY PLAN: SELF DESIGN + HYDROSTATICS & BONJEAN : DIRECT COMPUTATION FROM BODY PLAN FLOODABLE LENGTH & FREEBOARD : DIRECT COMPUTATION FROM LINES & BODY PLAN * STRUCTURE : SELF DESIGN & COMPUTED BASED ON LOAD DESIGN Design Phase SHIP WEIGHT ESTIMATED : COMPUTED BASED ON SHIP COMPONENTS 4, CAPACITIES, TRIM, INTACT & DAMAGED STABILITY: COMPUTED BASED ON SHIP GEOMETRY AND WEIGHT y COST ESTIMATE : COMPUTED BASED ON BOAT COMPONENTS Experiment Phase POWERING : EXPERIMENTAL WORKS FOR R1 & EHP, COMPUTATION FOR BHP AND ENGINE SELECTION PREDICTION: MODEL - FULL-SCALE BOAT HYDRODYNAMICS : EXPERIMENTAL WORK BASED ON SHIP GEOMETRY. BOATS BEHAVIOR AGAINST ROUGH SEAS (MOTION) PREDICTION : MODEL - FULL-SCALE BOAT DESIGN CRITERIA FOR SEA KEEPING PERFORMANCE? YES BLUE PRINT & FINAL REPORT Fig. 2. Flowchart of Research Implementation.
B. Experimental Work Experimental work will be executed for two design parameters i.e. Resistance and Powering. Total Resistance and Effective Horsepower will be achieved by the experiment of boat modeling where from here, the results should be predicted for the full-scale boat. Rules and regulations for towing tank works and prediction for full-scale boat will be applied in this work. Furthermore, the treatment for dimensions and position for the outer body will be done during the experiment. The decision will be made for the parameters of outer body with minimum resistance for the practical application with consideration of other design parameters. BHP may be achieved by computation with considering to selected screw-propellers. Sea keeping. Configurations and dimensions of the boat, for the meantime, will be tested for the experiment of boat motions. The experiment for boat motions (pitching, heaving, rolling) will be conducted for rough sea conditions. The experiment include also boat behavior and speed loss for the rough seas. Rules and regulations for towing tank works and prediction for full-scale boat will be applied in this experiment., Data Processing and Analysis. Results of computations will be processed and analyzed based on the product of each design parameter. Processing and analysis will be executed for each iteration stage where the decision of boat parameters to be based on hydrodynamics results with consideration of other design parameters. The parameters of boat hydrodynamics, in fact, may answer the mission requirements of boat beside boat lay-out and systems. When the designed boat has fulfilled the criterion of mission requirements, then the boat may be judged to be suitable for the full-scale boat. Control of Design Parameters. The design process runs for theoretical and experimental works. Computation during design phase where theoretical concepts are introduced. In this phase, all design parameters will be fulfilled as required. This works will be executed for several iterations until the design criteria will be obtained. This work will be followed by experimental works in order to obtain boat performances in still and rough seas. However, sea keeping characteristic of boat, found from experimental works of modeling, will be the control design parameter to determine the designed boat applied as prototype for passenger Trimaran boat.
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