With feedback like ‘amazing experience’ and’ 'I’ll never again work on any other type of vessel in winter’ being stated by crews on X-BOW® vessels, it is hard to ignore the impact this hull innovation has had since it first appeared in 2005.
The X-BOW® not only ranks as one of the most visual representations of forward thinking in ship design, but also as one of the most functional. The X-BOW® vessels in operation or under construction rank from cruise vessels for benign areas, to offshore wind vessels for sea states up to 3 m significant wave height, to powerful workhorses such as offshore oil & gas service vessels and ultralong-distance towing vessels that have to endure rugged conditions while still performing exact and precise work.
"No rolling, no spray, just pure fun"
Captain on 'NAO Prosper'
The X-BOW® eliminates slamming from head sea, and noise and vibrations are minimized, keeping up comfort even in harsh conditions. It allows the work to continue undisturbed.
According to an article in The Motorship, the owners of the seismic research vessels 'Oceanic Sirius' and 'Oceanic Vega' consider Ulstein’s X-BOW® configuration to be particularly suitable for the demands of the seismic industry, offering reduced surging and turbulence, lower added resistance and smoother bow immergence, leading to reduced operational disturbance and involuntary speed reduction.
This video shows the two ALP Maritime Future Class vessels, ALP Keeper and ALP Sweeper, during their journey from Singapore to Luanda Offshore while towing an FPSO in Q2 2018. Wave height at the time of filming was approx 6-7 metres. Filmed by third engineer Jan Dootjes.
Completed mission in time
When leaving Esbjerg, DK, in January 2016, the platform supply vessel NAO Guardian was heading for a mission in the North Sea. Wind and waves were tough, up to 40 knots from west-south west, but due to the X-BOW® seakeeping characteristics, the vessel could keep up speed, and completed its mission in time and returned to base. A conventional bow vessel which left Esbjerg at the same time needed to slow down, missed the weather window, and had to wait three days before mission was completed. The crew on this vessel filmed the X-BOW® vessel on their way to the oil field.
Higher speed as a result of the X-BOW
A similar story comes from the captain on NAO Fighter, a platform supply vessel of the PX121 design, stating that the vessel is the best he’s been on:
“I've been Captain on several vessels before. If I were a newly-educated captain planning for a North Sea career, a vessel of this type would be my preferred choice."
He continues: "This is a remarkably efficient and comfortable vessel in all weather conditions. Wind and seas have little impact on the vessel’s performance compared to conventional PSVs. We can compare performance directly when steaming on the same tracks to the oil fields: With the same weather conditions and 3-5 metres head sea within 30 degrees of the bow, our ship can easily and comfortably maintain a speed of 12-13 knots, while the other vessels have to reduce their speed to 7-8 knots. The higher speed comes as a result of the ‘X-BOW® effect’.”
Helicopter could land on the X-BOW® vessel
Another example of undisturbed work is the seismic research vessel WG Magellan, a ship in the Shearwater Geoservices fleet, which was working shoulder to shoulder with a conventional bow vessel in rough sea conditions. The ship’s master on the WG Magellan calculated his vessel’s movements to be some 20 per cent lower than the other. This meant that the helicopter could land on the X-BOW® vessel, but not on the other one.
Surfing on top of the waves
The Captain of the first X-BOW® vessel, the anchor handling tug supply vessel Bourbon Orca, reported that: "We could easily tow without the high dynamic tension variations experienced with traditional bow forms in bad weather conditions. And in transit in head seas we kept high speed, floating on top of the waves, with a substantial reduction in heave movements and stamping." Read the captain's story - surfing on top of the waves.
A smooth sail on heavy seas
In the offshore sector, comfort is not something to be discarded lightly. Offshore vessels often have a complement of technicians, scientists, oil workers or other working passengers, with complicated, intensive tasks to perform. They need a sound, reliable platform to do their work, and need to be able to trust in the vessel being able to hold its own in some of the hostile environments they could be working in. What they do not need is to be bounced about in bad weather and be too tired to do their work.
“The vessel is extremely quiet when underway, and minimal vibrations are felt in heavy seas. It is a ride of luxury," are among the statements by masters on twelve platform supply vessels of Ulstein’s design, originally ordered by Deep Sea Supply and now owned by Solstad, of which several are operating in the North Sea.
Getting complete rest
The captain on the offshore wind vessel Windea La Cour reported that “it is very silent onboard, and very little vibrations. This is a pleasant work place, not the least for the onshore technicians we are transporting.”
Others comment that the X-BOW® vessels “respond and behave much better than others we have worked on. We do not have to reduce speed as much, and less movement means that we get to sleep better."
"I love the X-BOW®! We can easily feel the positive effects in bad weather. The ship is behaving much better, and we can more easily keep up the speed. And I manage to sleep easily, even in bad weather."
Second officer on 'Polarcus Naila'
Another statement comes from the chief officer on the seismic vessel Polarcus Adira: “The calmer movements in the X-BOW® vessels have a big impact on the crew's well-being.”
Undisturbed rest is certainly also of high importance to passengers on cruise vessels. They are also eager to see the splendid surroundings, such as the unobstructed view of dolphins playing around the ship's bow:
Now back to the X-BOW® effect;
The absence of slamming means no sea spray. The Captain on the platform supply vessel Bourbon Mistral put it this way:
"On ships with conventional bows, the wheelhouse windows get sprayed. Spray is non-existent on this vessel”.
For cruise vessels, the lack of spray means that the observation decks stay dry, for the comfort and safety of the passengers. Here in the words of Aurora Expeditions, the operator of the first X-BOW® cruise ship:
“As the X-BOW® allows the Greg Mortimer to absorb the impact of heavy seas, ocean spray is also reduced. This means that during safe conditions, it's possible for you to venture out to the many observation desks and take a photo of the scenery without being drenched by the spray of a rogue wave.»
On 'Greg Mortimer's first journey, she came across very bad weather after leaving Cape Town heading for Ushuaia, Argentina. According to the Captain, the waves were 8-10 metres, with some waves reaching above deck 5, and strong winds. The vessel still kept high speed of 12-13 knots, with only 1 knot speed loss.
“It’s a totally different experience! In big seas, I kept waiting for the slamming, but it never came. You don’t feel the sea, you have to relearn how to interpret the vessel behaviour. Other ships can only keep half the speed,” says Captain Ulf-Peter Lindstrøm.
With such excellent sea-keeping capabilities, the vessel can swiftly transit open stretches of water. The vessel speed when transiting can be high even in adverse weather without reducing comfort on board. This means that the transit time in open seas can be reduced and will be more predictable, and the time schedule is more easily held.
Reduced fuel and emissions
Noteworthy is the positive side effect of less hull resistance, leading to significant fuel reductions. This is a benefit to the owner, and the natural environment too, considering the reductions in CO2, NOx, SOx and PM emissions.
This effect is stated by several captains, as in this film, which is the feedback from the captain on the Bourbon Monsoon.
Reduced fuel is also noticeable with the X-STERN®. When commenting on keeping the stern to the weather while on DP, the DP operator on the Windea La Cour said: If the weather is not too adverse, the ship stays on the spot with two thrusters running, which leads to substantial reduction in fuel consumption, instead of keeping the vessel on full DP.
The first master of the Bourbon Orca put it this way: "Due to a favourable combination of diesel electric propulsion, azimuths and the X-BOW®, the Bourbon Orca has a proven record of up to 50% less fuel consumption in typical anchor handling operations compared to conventional anchor handling vessels."
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