One such change which made a splash in the maritime industry was the introduction of X-bow by the Norwegian Ulstein Group. Since the inception of their first ship M/V Bourbon Orca in 2005 several other ship building yards/companies have used their design.
The X-bow comprises of a backward sloping bow starting at the extreme front of the vessel. This results in a continuous and smooth bow shape as shown below.
Designing such a vessel involves proper weight distribution in the forward region which allows for submission and sharper bow shape. Increased volume up front WITH SLOWLY INCREASE BUOYANCY FORCE allows it to efficiently respond to larger waves.
So, what are the factors that make X-bow better than the conventional?
- Better comfort and efficiency – model tests by the Ulstein Group at MARIN revealed that the short duration of speed loss due to wave impact is almost negligible, giving the captain the confidence to sail at higher speeds.
- Lower level of vibrations.
- Lower resistance due to absence of flare.
- Better dynamic positioning due to lower wave-drift forces at zero speed compared to the conventional bow.
- Better deck capacity – due to better initial stability compared to conventional bow. Due to higher initial stability the deck load capacity is higher on X-bow.
- Reduced power consumption – the X-bow shape reduces pitch/heave accelerations and speed loss in waves, which renders higher speed transit and reduced power consumption.
- Reduced emissions – reduced fuel consumption leads to improved fuel efficiency hence, reduces emissions to air.
- Labour costs was reduced by 15% in comparison to the conventional bulbous bow construction cost.
- Cost of assembly, welding, bending & rigging was cut by more than 50%.
- Adjustment and fitting works were reduced by 15% due to simplified forms of outer shell butt joints.
By reduced power consumption by 25% on DPX Stern concept been exposed in early 2015 by Ulstein.