Friday, 22 August 2014

An Interview with Dr. Stephen Payne

Dr. Stephen Payne

Dr. Stephen Payne, the Naval Architect and Chief Designer of Queen Mary 2, shot to fame after fulfilling his childhood dream. Stephen was the Vice President and Chief Naval Architect of Carnival Corporate Shipbuilding till 2010 and served the company for 26 years as the designer of many of their ships. He was also the President and Fellow of The Royal Institution of Naval Architects (RINA), UK. 

Stephen was awarded with SNAME Rear Admiral Land MedalHonorary Doctorate of Science University of SouthamptonOfficer of the Most Excellent Order of the British Empire OBEMerchant Navy Medal MNMSolent EBP Amazing Person Award, and many others. In 2011, he founded PFJ Maritime Consulting Limited and is presently the Founding Partner of the firm. He also likes to involve himself in interaction with students and after-dinner talks at various youth forums. 

In his interview with us, Stephen shared his experience in designing the Queen Mary 2, and his predictions on the future of the shipping industry. Not only that; he had some message for the youth too!

What was the biggest obstacle during the design of The Queen Mary 2? How did you overcome it?

The biggest obstacle was convincing everybody that for transatlantic service a true liner was needed and not just a cruise ship that looked like a liner. The problem was that from moving from a cruise ship to a liner entailed a 40% premium because of the extra power, strength, sea margin and shape considerations. I overcame this through maximising the number of balcony cabins by moving the main public rooms low down in the ship to provide sufficient height for the first passenger cabin deck to be a balcony deck with high revenue cabins.

For the last five years, the graphs of the maritime industry have seen a negative slope. In such scenarios, what qualities do ship design and shipbuilding companies look for, in Naval Architecture graduates? What are the talents that the industry is yet in need of?

The shipping companies, classification societies and shipyards are all looking for graduates that have a grasp of the fundamentals of efficient design with a flair for innovation and thinking outside the box. Everyone is looking at fuel economy from propulsive efficiency and auxiliary load. This will become even more acute as new environmental regulations on NOx and SOx begin to bite and owners have to either switch to more refined and expensive fuels or invest in scrubbing technology or future viable alternatives.

What do you think, is the scope of entrepreneurship for Naval Architects? 

I think the scope for entrepreneurship within naval architecture is vast. You only have to look at recent advances such as air-injection for hull lubrication to realise the scope for future innovation and entrepreneurship is boundless.

From the time you set foot into the ship design and building industry, to now; how has the industry changed in these years? And what changes do you predict in the recent future?

With regards passenger ship design, the biggest change I believe is the proliferation of balcony cabins which began with the introduction of Royal Princess in 1984. Her unique all outside/all balcony design set new standards which has been emulated ever since. The diesel has supplanted steam propulsion across almost all commercial shipping, either with direct drive, geared drive or with electric drive. The gas turbine showed some promise with its incredible power density but the high price of its fuel has seen it decline in recent years. However, the new environmental regulations mentioned earlier may see the turbines show some advantage. The immediate future heralds the potential of LNG but the future must inevitably point towards a compact marinised nuclear reactor –but that’s some way off, not because the technology doesn't exist, but public perception is generally negative at this time. As fossil fuel become scarcer in the future, nuclear will have to be considered as an option. As for the marine industry as a whole, when I joined it in 1985 there was still very much of a “family business” attitude. Sadly, this has largely disappeared as the smaller companies have been absorbed into huge corporations. Business has become more cut-throat and impersonal –but perhaps that’s the price of progress!

What percentage of designers of the Queen Mary 2 were from the younger age group? Did that percent of youth play an important role in the design?

I was 37 when I received the commission to design Queen Mary 2. The marine engineer on the project was somewhat younger, as was the electronics engineer. The structural engineer and safety specialists on the team were of comparable age to me and it was only the two electrical engineers that were older, both being in their fifties and sixties. So, we were a relatively young team that worked well together. Many of the shipyard engineers were relatively young as well.

If there was a debate on Naval Architecture being an Art or a Science, which side would you speak for? And why?

My marine engineering colleagues have always asserted that naval architecture is a “black art”! Whereas Art can be abstract, Science can be defined as a branch of study, concerned with facts, principles and methods. I am therefore firmly in the camp that sees naval architecture as a “Science”! To be successful, a ship has to be designed according to known principles –there’s no room for art when dealing with issues such as stability!

Wednesday, 13 August 2014

Deep Sea Risers

Technological advances have created economically viable solutions to the complications of well-control methods that are created by subsea blowout preventer systems. Further, wells are being drilled in waters deeper than before, and subsea technology has made it possible. Innovations have led to the invention of different types of Marine Riser Systems(Deep Sea Riser).

How Do Risers Work?

They transfer the materials from sea floor to production and drilling facilities atop the water's surface, as well as from the facility to the seafloor. Subsea risers are a type of pipeline developed for this type of vertical transportation. Whether serving as production or import/export vehicles, risers are the connection between the subsea field developments and production and drilling facilities.

Similar to pipelines or flowlines, risers transport produced hydrocarbons, as well as production materials, such as injection fluids, control fluids and gas lift. Usually insulated to withstand seafloor temperatures, riser can be either rigid or flexible.

The following video gives us a rough idea about Marine Riser System, later in the article the different types of risers are explained.

Types of Risers

There are a number of types of risers, including attached riser, pull tube risers, steel catenary risers, top-tensioned risers, risers towers and flexible riser configurations, as well as drilling risers.

Steel catenary risers

Build on catenary equation that has helped to create bridges around the world. Used for connecting the sea floors to the floating facilities above,as well as connect two floating platforms together. These are common on TLP's, spars & FPSO's, as well as fixed structures, compliant towers & gravity structures. While this curved riser can withstand some motion, excessive movement can cause problems.

Fig. 1: Steel catenary riser
(Image Courtesy: Google Images)

Attached risers

 They are developed on fixed platforms, compliant towers and concrete gravity structures. They are clamped to the side of the fixed facilities, connecting the seabed to the production facility above. Usually fabricated in sections, the riser section closest to the seafloor is joined with a flowline or export pipeline, and clamped to the side of the facility, until the top riser section is joined with the processing equipment atop the facility.

Top-tensioned risers

Used on TLP's and spars. These are completely vertical riser system that terminates directly below the facility. Although moored, these floating facilities are able to move laterally with the winds & waves. Because the rigid risers are also fixed to the sea floor, vertical displacement occurs between between the top of the riser and its connection point on the facility. There are two solutions for this issue. A motion compensator can be included in the top tensioning riser system that keeps constant tension on the riser by expanding and contacting with the movements of the facility. Also, buoyancy cans, can be deployed around the outside of the riser to keep it afloat. Then the top of the rigid vertical top-tensioned riser is connected to the facility by flexible pipe, which is better able to accommodate the movements of the facility. 

Fig. 2:  Top-tensioned riser
(Image Courtesy: Google Images)

Pull tube risers

These are pipelines threaded up the center of the facility. For pull tube riser, a pull tube with a diameter wider than the riser is preinstalled on the facility. Then, a wire is attached to the pipeline or flowline on the seafloor. The line is then pulled through the pull tube to the topsides, bringing the pipe along with it.

Riser Towers

Ideal for ultra-Deep water environments, this riser design incorporates a steel column tower that reaches almost to the surface of the water, and this tower is topped with a massive buoyancy tank. The risers are located inside the tower, spanning the distance from the seafloor to the top of the tower and the buoyancy tanks. The buoyancy of the tanks keeps the risers tensioned in place. Flexible risers are then converted to the vertical risers and ultimately to the facility above.

Fig. 3:  Riser Tower
(Image Courtesy: Google Images)

Flexible risers

A hybrid that can accommodate a number of different situations. It can withstand both vertical and horizontal movement, making them ideal for use with floating facilities. This flexible pipe was originally used to connect production equipment aboard a floating facility to production and export risers, but now it is found as a primary riser solution as well. There area number of configurations for flexible risers, including the steep S and lazy S that utilize anchored buoyancy modules, as well as steep wave and lazy wave that incorporates buoyancy modules.

Fig. 4:  Flexible riser(Image Courtesy: Google Images)

Drilling risers

These transfer mud to the surface during drilling activities. Connected to the subsea BOP(blowout preventer) stack at the bottom and the rig at the top, drilling risers temporarily connect the well bore to the surface to ensure drilling fluids to not leak into the water.LSD

Fig. 5:  Drilling riser
(Image Courtesy: Google Images)

Article By: Tanumoy Sinha

Recommended Readings: Riser TechnologyRigzone training

Sunday, 3 August 2014

E-Ship 1: Magnus Sailing

Today's shipping industry contributes to about 5% of total carbon dioxide emission and the GHG emissions have shot up to 2.7% according to the studies conducted by International Maritime Organization. Oil prices have frenetically hit the ceiling with increment rates almost three times higher than those of the nineties. In such a scenario, the stratagem of ship designers has been to attain the optimum benchmark between prevailing fuel economy and environmental safety standards. Visions have shifted towards unconventional propulsion systems and use of renewable resources of energy is rapidly burgeoning. 

Realizing this, Enercon, with its 20 years experience in wind power engineering, has taken one of the most innovative steps in the design of its wind turbine carrier, E SHIP 1. The fact that it is designed to carry offshore wind turbines to their sites, is just like another story. But what will probably baffle you is that they have used the same physics to propel the ship, that a footballer uses while doing the banana free kicks! (Watch video) It is called the Magnus EffectTo understand this effect, imagine a fluid medium (like water or wind) moving at some velocity in some direction. Now let's place a stationary cylinder or a ball (let's take a cylinder here) in the medium and mechanically induce a rotation in the cylinder about its axis. Now refer to Figure 1. and tally what you're going to read.

Fig. 1: The Magnus Effect
(Image Courtesy: Google Images)
The fluid will obviously pass around the boundary of the cylinder, but note the difference in the pattern of flow on both the sides of the cylinder. On the top side (as per the figure) the velocity of the cylinder opposes the fluid velocity (thanks to friction) therefore reducing the net fluid velocity on this side. Recall the famous Bernoulli's Equation, and you'll feel the pressure on this side increasing. On the lower side, the scenario is very much the opposite. Supported by the direction of rotation of cylinder, the fluid on this side has an increased velocity and therefore, reduced pressure. The pressure difference between the two sides of the cylinder results in a force that is vectored along the direction shown (from high pressure to low pressure), which now induces in the stationary cylinder, a translation motion along its direction. This effect is used to swing the balls in football, cricket, golf, tennis, table tennis and baseball. Now take a look at Figure 2 and we'll soon see how the designers used a 90 year old technology that was rejected long time back, to slice through fuel price issues.

Fig. 2: The ENERCON E-SHIP 1
(Image Courtesy: Google Images)

The 90-Years Old Rejected Technology

The ship is powered by a diesel electric propulsion system consisting of one Controllable Pitch Propeller and three rudders. But what is remarkable in the ship, is the set of four vertical cylindrical structures on the main deck. They, in operation along with the diesel-electric propulsion system actually help the ship save about 20% of its fuel consumption when there are beam winds, also reducing the load on the propeller.  And they do that exactly by the principle of Magnus Effect. When there is a beam wind, these cylinders are rotated about their axis by an electric drive so as to direct the resultant magnus force along the direction of required surge.The concept of these cylinders were developed by Anton Flettener, and hence received the name: Flettener Rotors. The direction and speed of rotation of all the four are automatically set by the electronic wind sensing and control system, which involves less crew work as in case of sail powered propulsion, also leaving less room for human errors. The vectorial representation of this is as shown in Figure 3.

Fig. 3: Magnus effect applied to a ship
(Image Courtesy: Enercon)

The Question You Missed

These flettener rotors are rotated by means of an electric drive. So the obvious question is, Why spend that energy on electricity when it could have been spent on the conventional diesel-electric propulsion system? This obviously seems like a paradox, as in, we are just reducing consumption of diesel and ending up generation some extra electric energy which would power rotors that finally use the wind energy. We have seen the fuel consumption drop by 20% when the rotors are used along with the diesel-electric drive. But have we dropped the total energy consumption? The answer is Yes. The hot exhaust fumes of the diesel engines that power the conventional propulsion don't go waste. They are led to run a Siemens steam turbine that generates the electricity used to spin the flettener rotor sails. Figure 4 shows the CFD estimated power savings with varying directions of wind (24 knots / 6 Beaufort Scale) at the design speed of 16 knots. The yellow dot shows the attained savings at the trials, which was successfully above the estimated levels.

Fig. 4: Power Saving (%) vs. Wind Direction
(Image Courtesy: Enercon)

The Green Hull

Enercon seems to have left no stones unturned to optimise the ship for minimum environmental effects. With a 20 year global experience in wind power engineering, they designed the hull of E-Ship 1 to aerodynamically offer less resistance, therefore cutting fuel consumption even more. Also, to protect the for'd placed superstructure from green waters in rough seas, the wave breaker was developed and tested. The resistance of the ship was further decreased by using a low-resistance hull coating below the waterline. 

Fig. 5: The break water in front of the superstructure

Oh, and one more fun fact: She uses her hear from the engines to cool her interiors. In case, you know, 20% wasn't much of a reduction to set new standards. LSD

Article By: Soumya Chakraborty

Recommended Readings: Dynamic performance of Flettner rotors with and without Thom discs. (University of Manchester, UK)