Feature 4 | MEGA YACHTS
requirements for Life Saving Appliances vary between Flag authorities. SOLAS 2009 probabilistic damage stability requirements will make this equivalence more difficult to apply as the two compartment standard no longer applies, and we await the clarification that will come about from the new Passenger Yacht Code. A new trend on some recent BCTQ
mega yacht projects has been to fit luxury lifeboat/tenders. Te advantage is that the lifeboats provide a useful function for taking guests to shore etc. These dual purpose custom tender/
lifeboats have so far been designed specifically for each yacht. As such each new design is considered as a prototype by the LSA code and therefore needs to be tested as if it were a prototype. With care, the competing requirements of the luxury tender and lifeboat can be adequately balanced.
Recent regulatory changes New damage stability regulations are included in SOLAS 2009. Tese regulations have been adopted in resolution MSC 194(80) in order to harmonise the damage stability requirements for cargo and passengership. These new requirements entered into force on 1 January 2009. For yachts over 3000gt and for those
yachts that are designed to carry more than 12 passengers, probabilistic damage stability calculations will need to be undertaken.
BCTQ was involved in the working group at IMO to develop “Floodable Length Surfaces - Te Ship subdivision design tool”, which allows the naval architect to understand the implications of adding deleting and moving transverse and longitudinal bulkheads. Here, the naval architect can visualise local survivability along the ship length, optimise the arrangement and decide whether the overall subdivision performance is satisfactory. Recent amendments to regulation 12A
of MARPOL Annex 1 were adopted in March 2006. Tese regulations need to be complied with if the yacht has an aggregate fuel oil capacity of over 600m3
. Depending
on the range and speed, yachts that are over 100m can easily carry greater than 600m3
.
As such they need to either protectively locate the FO tanks or, as an alternative, demonstrate equivalence through the Outflow calculations.
Owner and guest comfort In general, to achieve the low noise and vibrations levels in BCTQ specifications, a considerable amount of design and analysis effort has to be undertaken, by specialist noise and vibration consultants. Tis includes full finite element modelling for the vibration analysis. Additionally, a full noise model is generated for predicting noise levels throughout the yacht. In order to attain the noise and vibration levels required on these yachts the following
Motor Yacht Octopus - diesel electric propulsion.
• Diesel electric propulsion should be considered:
• Resiliently mounted generator sets • Extensive use of floating floors
• As well as the usual fire, thermal and acoustic insulation.
At an early stage in the design process,
before the mast and funnel design is finalised, either wind tunnel tests or Computational Fluid Dynamics analysis is used to predict the flow of exhausts in order to avoid exhausts being drawn down onto the open decks. Tis provides a tool to assess the merits of different mast and funnel designs.
Recent innovations BCTQ has had extensive experience with specifying diesel electric propulsion in yachts. Recent BCTQ diesel electric yachts include Octopus and Kogo, whilst we currently have others in build and out to tender. The main benefits of diesel electric
• Te ability to resiliently mount the diesel generators
propulsion for yachts are that the system provides:
• Greater redundancy with larger range of optimised efficiency
• Greater flexibility of machinery location
dynamic positioning. However, the disadvantages are as
follows:
• Potentially higher system losses, giving reduced efficiency at certain specific
• Diesel electric propulsion systems require more equipment to be installed
speeds
• Likewise the capital costs are higher and require higher levels of skill and
certification skill in the crew to run the systems.
On balance, based on our experience, it
is considered that yachts of the 100+ range do benefit from diesel electric propulsion systems. Podded propulsion has been utilised in cruiseships for a number of years, and
64 The Naval Architect July/August 2009
onboard with a corresponding increase in weight and a constraint on the space
• Ideal for yachts with a large range in speeds, trial, cruising manoeuvring, and
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