Trans RINA, Vol 154, Part C2, Intl J Marine Design, Jul - Dec 2012
General shapes of boat are straight and simple with strong influence minimalistic design trends. Taking individual nature of this project, resale of such a special craft could be an issue and the owner is likely to use it for considerable period. Thus, the boat should not get out of fashion too quickly.
Figure 8: Perspective view of R1200 lines plan
Figure 7: Analysis of R1200 catamaran seakeeping Vertical accelerations are presented in comparison with similar size monohull, at loaded condition displacement, speed 20kts at sea state 3, head wave, Pierson-Moskowitz spectrum.
7. HULL SHAPE AND CRAFT DYNAMICS
Careful study was undertaken at stage of hull shape design by combination of experience from our previous catamarans with extensive calculations.
Resistance predictions were performed using Molland, Muller-Graf and Pham’s methods [14]. Numerical analysis was made for optimal hull spacing and types of hull shapes (chine of
presented on fig.6. It can be noted that
displacements and operational speeds of 15-22kts there exists a transitional area where wider beam and combined hull shapes are advantageous. A compromise has been made by hull shaping with round entries and chine sterns. Recommendations on hull
round bilge); some results are in range of
shapes and
overall proportions from [16] were followed; resulting hull shape is presented on fig.8.
Seakeeping and ride comfort were of special concern for R1200 design in terms of acceleration levels, operational heel and trim angles. Important features of catamaran concept are advantageous roll and pitch characteristics that become vital for use of wheelchair on board. On catamarans, roll amplitude and period are usually smaller compared with monohulls and they tend to decrease with increase of demihull spacing. In practice is means that those
wider catamarans provide very stable and ©2013: The Royal Institution of Naval Architects
Figure 9: X-Ray view of R1200 interior
comfortable platform, while contemporary monohull motor yachts tend to roll significantly. Thus architectural type of relatively wide catamaran is seen as right choice
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