Planning and executing a superyacht system refit
by Dudley Dawson
Many refits are primarily cosmetic surgery, intended to update the appearance of a yacht whose glory has faded. Such a facelift is often just what is needed to refresh the enthusiasm of the owner, ensure a sale or improve the yacht’s standing in the charter market.
In contrast, the refitting of mechanical and electrical systems is akin to major internal surgery. The results may be less immediately apparent but they cure problems, make life more comfortable and add considerably to the yacht’s productive lifespan and its value.
Among the obvious candidates for refit are:
The main propulsion system;
Generators and electrical system;
Heating, ventilation and air-conditioning (HVAC);
These systems are often interrelated, so be sure to coordinate planning across the disciplines. The use of PERT (program evaluation and review technique), Gantt charts and other techniques, including critical path analysis, can help keep the project on track and preclude one job from impeding another.
For the propulsion system, modern diesel engines are up to 10 per cent more fuel efficient than older models, thus offering a combination of lower fuel use and increased range. They are also often lighter and smaller, resulting in reduced displacement with further fuel savings. As well as burning less fuel, additional carbon offset is often achieved through cleaner fuel burn enabled by new electronic controls.
Keep in mind, however, that new engines are only part of the formula for achieving better performance.
Whether or not you are considering new engines, custom propellers can be well worth their cost. Nelson DuRant, owner of Palmetto Props in Charleston, South Carolina, says that $20,000 to $40,000 per pair is a reasonable price range if your yacht is a 25m sport fisher, but cost varies more with power and speed than with length.
Prop prices can run well into six figures for superyachts, because of the larger physical dimensions and the precise technical specs for low-cavitation wheels to control vibration.
The payback to using custom propellers are substantial gains in the propulsive coefficient and thus better fuel economy, with savings sometimes approaching 30 per cent. However, the ideal propeller may require a change in the reduction gear ratio, and that can mean new shafts, struts and bearings, so a compromise is sometimes more sensible if the yacht’s annual cruising hours are low.
You might also consider refitting the exhausts even if the other machinery stays the same. The conditions these systems must withstand are among the worst imaginable, often limiting their effective life. New technology mufflers lower noise, and many large yachts are being fitted with soot-arresting systems, mostly for dry-stack generator exhausts.
Improving electrical service
Changes to the ship-service electrical system are sometimes merely desirable, at other times dictated by the electrical demands of the growing number of modern conveniences aboard.
While basic generator design has changed little in recent years, accoutrements have. Better support systems, many incorporating air-bag mounts and intermediate mass-damping plates, minimise vibrations transferred into a yacht’s structure. Better electronics ease the control of multiple-generator installations.
What has not changed is the need for electrical load analysis before specifying a new generator. Many yachts carry oversized generators with too much capacity ‘just in case’. This can lead to maintenance issues and even the need for an energy-wasting load bank. Few activities are more blatantly ‘ungreen’ than burning fossil fuel unnecessarily, creating CO2 and heating the ocean just as a matter of convenience.
When evaluating a refit of the electrical system, consider the possibility of a diesel-electric drive train or hybrid system. These are still expensive but the wider availability of appropriate equipment and the resultant decrease in cost makes such systems attractive to owners with particular requirements.
Diesel-electric propulsion systems are particularly suitable for larger superyachts. Knight & Carver Maritime, in southern California and the venue for many superyacht refits, has been acquired by hybrid systems supplier Arc Lite Power with an eye to developing a major presence in such systems.
In a statement announcing the acquisition, Arc Lite notes: ‘The $30 million (€22 million) total investment will expand the capabilities of the combined companies to serve the emerging ‘green marine’ market.’
For other owners, changes to the distribution system are carried out at the same time as a generator refit. Automatic main and shore power panels make life easier both at sea and in port.
Multiplexed electrical power distribution systems, such as the OctoPlex system by Moritz Aerospace for air-conditioning systems, or the Czone system by BEP Marine for DC systems, allow every switch, fixture and appliance to be monitored and controlled for maximum convenience.
Other options for modernising electrical systems include LCD lighting, which reduces both heat and power consumption, and variable-speed controllers on large motors to reduce startup loads and flickering lights.