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.
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 PSV s. 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 Farstad, 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:
People also love the X-STERN
10 years after the X-BOW, the X-STERN was introduced, implementing the X-BOW effect to the aft end of the ship. This adds to the flexibility of the ship. The Windea La Cour is the first vessel which also features the X-STERN.
The DP operator Matthias Giebichenstein explains the positive effects this way:
“From midnight till 6 a.m., my main task as a dynamic positioning operator will be to keep the vessel on standby mode. I prefer to keep the stern towards the weather. With the stern towards the weather, we experience absolutely no slamming and vibrations, not even when we are in transfer, and people love it. They get complete rest in between their maintenance shifts.”
Check out the vessel when testing the X-STERN at full backward speed during sea trial.
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, who will be operator of the first X-BOW cruise ship, currently under construction:
“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.»
With such excellent sea-keeping capabilities, the vessel can swiftly transfer from one calm area to another. 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 will be 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."
Please contact us for more information
Ulstein Design & Solutions AS
P. O. Box 278
Tel: +47 7000 8000
Ulstein Design & Solutions B.V.
Cornerstone Building (6th floor)Tel: +31 10 475 00 11
Rotterdam Airportplein 32
3045 AP Rotterdam
Ulstein Verft AS
P. O. Box 158
Tel: +47 7000 8000