Management is not just pure science; it could be termed an art. It involves people in any organization, each of which maybe unique. These management myths aren’t just the most common, they’re also some of the most mythical and therefore easy to debunk. And one thing successful managers have in common is that they don’t drink the Kool-Aid or buy into BS fads. So, if you aspire to be a successful manager, don’t buy these:

Some Management Myths

 It’s ironic that society is okay with bad spouses, bad marriages, bad workers, bad professionals - hell, bad people - but not bad bosses, poor managers are a bad thing.. There’s a bell curve for all things involving people. It’s reality; it can never and will never change. Deal with it.

It’s not what you know but could be who you know. The mantra of the perpetual underachiever, the assumption being that because he can’t get a promotion it means the guy who did must know somebody. The truth is that overachievers work harder and yes, they schmooze harder too. That’s why they know more successful people and are therefore exposed to more opportunities.

It’s the path to big bucks. For the vast majority, that’s simply not the case. There’s at least as good a chance that you’ll hit the jackpot as a professional, individual contributor, or entrepreneur. That’s because the big bucks are in a thin sliver of executive management and few managers ever get there.

You should be prepared for the job. Sure, young managers should get some basic training, but anyone who says he was adequately prepared for his first management role is "BSing". A great deal of management skill simply can’t be taught; it’s best learned on the job, under fire in the hot soup, into the real world.

Abusive, confrontational, or dysfunctional managers are bad managers. Some of the most successful managers of our time fit that description: Larry Ellison, Bill Gates, Andy Grove, and Steve Jobs, to name a few famous ones. Sure, there are plenty of best-selling books that promote the myth, but like it or not, I’ve never observed a correlation.

It’s all about managing people. This is probably the notion I most strongly want to dispel. Sure, managing people is a big component, especially for line managers. And employees certainly want to believe they’re first and foremost in the hearts and minds of their bosses. But if you look at the specific goals - how success is defined for most managers - they’re typically more about managing a function or a business than about managing people.

Leadership and management are unrelated. I hear this all the time and it’s a huge misconception. While it is true that there are different skill-sets, they’re still intimately related. The truth is that good management skills make better leaders and the converse is also true. I would argue that great management requires excellent leadership skills.

MBAs make better managers. Yes, you learn a lot getting an MBA. Yes, it’s a good piece of paper to have - especially from a top notch school - if you aspire to be in senior management. There is some credible evidence that it will make you or anyone else a better manager. That’s largely because management is partly more art than science. It’s tougher to get in than it is to do. The truth is just the opposite. If you’re capable, you’ll become a top notch manager. But it takes a lot more than that to become a successful manager not the least the visionary leader.

You should be able to do the jobs of those you manage. For some people in some jobs - primarily line managers - it can help quite a fair bit. In the vast majority of cases, however, there’s little correlation and it decreases further the higher you go up the management chain.

Perhaps the supreme, overriding uber-myth here is that there’s a formula for management success. As long as people are unique individuals and organizations are unique entities - and they surely are - there can be no formula for successful management. Sure, certain qualities and processes work better for certain people in certain organizations and industries, but that’s a far cry from a general blueprint for management success. It simply doesn’t exist. So if you stop looking for formulas, you’ll go a long way to becoming a more successful manager.

Every so often there is talk about whether you should or shouldn’t get an MBA. The only thing all those stories have in common is that those who wrote them likely have a stake in the presentation.
Also, it’s indefensible to be screwing around with folk’s career potential and ability to land jobs at a time like this. This is a time for the truth, like it or not. So here it is, no sugarcoating, no research that can be manipulated to make a point, just pure, unadulterated experience and simple logic.

You see alot of people have satisfying career, but you may need to fight tooth and nail to beat out competitors with MBAs from Harvard, Stanford, Cambridge and other top schools for executive-level jobs. It could be just a piece of paper, but that piece of paper is either desired or required for the vast majority of senior management jobs at companies big and small.

So, if you aspire to climb relatively high up the corporate ladder, you’ll have a far easier time if you get that piece of paper, especially if you get it from a top notch school. An MBA from a top notch school will indeed improve your prospects but those that are not so branded will still see yourself in a fair deal if you do proven your own capability. Otherwise, you’ll be swimming uphill your entire career.  If you’re not into climbing the corporate ladder, think you can make it on your own as an entrepreneur, or can’t afford or get into a top tier school, then it’s probably not worth it. All hype and headlines aside, that’s the simple truth.

Why Smart People Make Lousy Teams

Okay, maybe it’s not all that bad. But we’ve all seen groups of supposedly smart people who just can’t work well together. That’s because, according to recent research from Massachusetts Institute of Technology, Carnegie Mellon, and Union College, raw smarts doesn’t have much to do with team performance.

Some research has placed nearly 700 people into groups of between two and five, then gave them problems to solve, such as visual puzzles, games, negotiations, and logical analysis. Here’s what they found:

Individual smarts doesn’t affect performance. The average intelligence of team members wasn’t related to team performance. So if you’ve got a team that’s struggling, putting a couple of really smart people on it isn’t going to help.

EQ–emotional intelligence– is more important than IQ. Good communication and good coordination make teams function well. To get that, you need people who are good at reading and responding to other peoples’ emotions. Teams that included even one person with superior skills in this regard had better performance.

A ’strong’ personality hurts performance. Groups where one person dominated the conversation or the decision-making, or where people didn’t do as well taking turns, had worse performance. This correlates well with other research that shows ’stronger’ leaders are often less effective than those who perceive themselves to be less powerful.

In business, it’s not always easy to change the composition of a team, and just because a team is all-male shouldn’t give it license to be socially inept. Writing for Psychology Today, Heidi Grant Halvorson suggests a number of ways any team can become more socially aware, and therefore, higher performing:

Create opportunities for team members to express their feelings, and for others to respond to them. Encourage face-time whenever possible (emotions are difficult to read on the phone, and nearly impossible over email). Cultivating a work environment where team members experiences are acknowledged and understood will create teams that are smarter, happier, and far more successful.

Teams can be smarter and more effective than the individuals who make up the team - the whole can indeed be bigger and better than just the sum of its parts, but only under the right circumstances.

A recent study conducted by researchers at MIT, Carnegie Mellon, and Union College shows that the collective intelligence of a small group working together uniquely predicts their performance across a wide variety of tasks. In the study, nearly 700 people were placed in groups of 2 to 5, and their ability to solve problems as a team was found to strongly predict their subsequent success on tasks as diverse as visual puzzles, games, negotiations, and logical analysis.

The average intelligence of members (measured individually, rather than as a group) did not predict team performance at all, and that's really important. In other words, simply having a couple of really smart people in the group didn't necessarily make the group itself any smarter.

It turns out that the collective intelligence of the team will only meet or exceed its individual potential if the right kind of internal dynamics are in place. The researchers found that what is needed for a group to be "smart" is effective coordination and communication, and that this is most likely to be the present in groups with members who were more socially sensitive.

When groups contained people who were particularly skilled when it comes to perceiving and responding to others' emotions, they demonstrated greater collective intelligence, and superior performance again and again. Not surprisingly, groups where one person dominated in conversation and decision-making were collectively less intelligent, and less effective.

So, how can you ensure that your team will be socially sensitive? The answer is simple: Try to add more women. Some studies found taht teams that contained more women were significantly more socially sensitive, and consequently more intelligent, than the male-dominated teams.

If you don't have the power to change the gender makeup of your teams, fear not. Their collective intelligence can still develop and improve - through better, more sensitive means of working together, or better collaboration tools. Create opportunities for team members to express their feelings, and for others to respond to them. Encourage face-time whenever possible (emotions are difficult to read on the phone, and nearly impossible over email). Cultivating a work environment where team members experiences are acknowledged and understood will create teams that are smarter, happier, and far more successful

“Downsizing”

Many mainstream articles, business press, etc,  characterize CEOs as “courageous” because they instituted a downsizing during the bad economy and worldwide business is showing signs of slowing down. The decision to sack or terminate employees is so difficult, the CEO who takes that path must be a brave and live a lonely soul. He’s putting the interests of the investors ahead of his own kindhearted inclinations, and making the difficult decisions that will allow the company to remain in the survival state.  How, exactly, did the company get into a situation where it needed to fire people in order to remain competitive? Sure, markets change like crazy in today’s world and business conditions become challenging. But isn’t it the job of the CEO and the management team to know or able to predict those changes, and to handle the company appropriately, and retrain staff to take on future competition, so that those challenges can be addressed?

Is Downsizing a sign of failure in business? Is it means that management has done poorly all these years and failed instead of doing the right thing — which is to quit without severance — they’re passing along the penalty for that failure to the staff who, in good faith, tried to execute the flawed corporate strategy that nowadays top executive management have been trained and pursued.

Is that why top managers chose the word “downsizing”? Does it makes the results of failure sound like a strategy, rather than a desperate way to remain profitable after the executive management has made a complete flop breakfast of things?

So, as we go forward, let’s stop calling it downsizing. Should it be called what it is: firing productive workers because top management was a bunch of overpaid pinhead losers who shouldn’t be allowed to run a company again.

“Leadership”

Before he passed away, Mr Peter Drucker was interviewed and in that interview, he pointed out what should be obvious to everyone — that all this talk about “leadership” is a bunch of bull "shit".

Yeah, yeah, the idea of leadership sounds neat — especially if you’re in management — and it makes a manager sound all charismatic and exciting.

But what is a “leader,” anyway? What does a “leader” do?

We could not hear the term without thinking of the leader as if a marching band. That’s the person who takes a big stick and makes it go up and down, while the band does the work of actually making the music.

One reason we thought of that image is that, in our experience, most of the time the “leader” of the team is the person who found a parade and then got out in front of it. The concept of a “leader” means that credit for what the team does probably would go to the leader. And you see it every day, in the bloated salaries paid to “business leaders” and in the ridiculous way that some CEOs parade themselves as if they were super rock stars.

You see it in the lower levels, too, where managers bloviate about leadership and “inspiring” people, when in fact they’re usually just making everyone under them want to "puke". Leadership is not gifted but through sheer experiences and years of learning and understanding the human side and the way to deal with day to day activities, the feedback and the nurturing of these knowledge and expertise that hone the individual to be true leaders.

What Drucker said — and most would agree with him — is that the business world doesn’t need leaders. It needs managers — one who can actually manage a team of staff in the big organization. Being a manager means being in service to the team of employees. It means giving the team credit and making everyone else successful.  So, as we go forward, let’s stop enabling all these tin-pot “leaders” by pretending that they’re doing anything other than grandstanding. Let’s value the real managers, who actually do the hard (and largely thankless) work of making other staff in the company productive.  Let's not bluff ourselves that young managers whom have started without much experience could act to be good leaders when they take on the throne.

“Empowerment”

 

Back in the 20th century, there was all kinds of talk about how technology was going to empower people. Applications like email and, later the Internet, would create a free-flow of ideas, making it possible for individuals and small organizations to counterbalance the power of large institutions.

Today, however, it’s abundantly clear that technology isn’t empowering employees; it’s empowering management to spy upon employees. And technology isn’t empowering small organizations; it’s making it easier for large organizations to drive the smaller ones out of business.

As evidence of this, look at what’s happening to Wiki-leaks, probably one of the only organizations in the world that’s actually making a stab at the kind of information empowerment that was promised in the past. The big financial institutions, one by one, are using their clout to shut it down, even though the organization has not been charged with any crime.

Consider as well, the so-called “net neutrality” act recently passed.

There’s a concept in business called “the law of inverse relevance” which can be stated as “the less you plan to do something, the most you must talk about it.” That generally takes the form of laws and regulations that do the exact opposite of what their title says they’re going to do.

The “net neutrality” act is a perfect example. Rather than making sure that the net remains neutral, it actually makes certain that wireless companies will be able to throttle any business or business concept that threatens their profits.

The way this “empowerment” concept plays out in business is the insane idea that new technology is going to make people more innovative, more entrepreneurial, more creative, yada, yada, yada. Such total BS. All those things come from the heart, not from the hand.

So, as we go forward, let’s stop talking about technology as “empowerment” and start talking about what really counts: human creativity freed from the limitations imposed by bonehead “leaders” who think they’re managing “human resources”.

Business Process Reengineering

The theory: Analyze the workflows and processes within your organization and rework them to achieve a defined business outcome. Set up cross-functional teams in order to re-engineer separate functional tasks into complete cross-functional processes. Integrate a wide number of business functions through enterprise resource planning, supply chain management, yada-yada-yada, etc., etc.

The reality: Forget about redesigning processes. Reengineering is all about layoffs. Top management uses the idea to justify firing people in order to make it seem like they’re actually doing something logical, rather than just temporarily boosting the stock price so that their short term stock options pay off big.

The result: A string of layoffs, followed by the total collapse of your company. Probably sooner rather than later.

The fad opinion: The whole idea is terminally idiotic. Massively changing a corporation while it’s operating is exactly like trying to redesign and retool an automobile while you’re driving down the highway. In any case, reengineering assumes that corporations fail because of lousy processes, when it’s almost ALWAYS the result of lousy management.

Your strategy if you do: If your company announces that it’s reengineering, suggest update your resume. Start networking and maybe line up your new position in another company as soon as possible. Even if you’re well positioned to survive the layoffs, you won’t want to work there after the reengineering has been going on for a while. 

Core Competency

The theory: Focus on the one thing that your firm does better than anyone else. That will make your strategy difficult for competitors to imitate and keep your organization from wasting time doing things that they’re not very good at.

The reality: Most organizations, like the managers that run them, are about as self aware as a turnip. As a result, they seldom know what they’re really good at. In many cases, organizations think they’re good at something but are actually successful for some completely different reason.

The result: Core competence generally ends up as a kind of myth that keeps a company locked into doing what it was successful at doing in the past. As a result, companies that focus on their core competence soon find that they have competitors running rings around them.

Like all management fads, this sounds like a great idea, but it must be implemented by corporate managers, which means that even if it were the most brilliant idea in the world, they would still bollix things up beyond all recognition.

Your strategy if you do: Get involved in the committee that’s suppose to determine the core competence. Make sure that whatever you do is the company’s core competence. If you fail, maybe better transfer to the group that did win the discussion.

RIG BOOK

Offshore Rigs Diesel Engine NOX Emission

The diesel engine combustion process mainly produces NO (approximately 60–90%) and little NO2in the combustion chamber. They are considered a mixture called NOX but only NO2 is relevant for air hygiene as a pollutant input. Diesel engines systematically produce NO2 from NO in catalytic converters. deNOx systems use it to oxidize and efficiently reduce soot particulates.

In air, NO oxidizes to NO2, a gas that irritates mucous membranes and is caustic when combined with moisture (acid rain). It increases asthma sufferers’ physical stress, especially when they exert themselves physically. NO2 has a ‘‘fertilizing’’ effect on plants, i.e. it promotes growth.

According to authority, a limit concentration of NO2 of 40mg/m2 will be in force in the EU in 2010.

Achieving the aforementioned limits will necessitate considerable efforts in all sectors, i.e. not only in the transportation but also the major offshore industry and shipping businesses will be required to reduce NOX emission worldwide.

The IMO (International Maritime Organization) imposed limits on NOX emissions for marine diesel engines

with power outputs >130 kW as of January 1, 2000. It plans to later adapt the limits determined from the test cycles dependent on use (main propulsion or auxiliary engine) and the mode of operation (constant speed or propeller drive) specified.

In 1999, EPA adopted regulations requiring new marine diesel engines to comply with emission standards

beginning in 2004 (tier 1) and 2007 (tier 2). 

In May 2008, EPA published new rules aimed at dramatically reducing air pollution from marine diesel engines.

↓ particulate matter (PM) emissions by 90%

↓ nitrogen oxide (NOx) emissions by 80 %

 

Tier 1 and Tier 2 emission standards currently applicable to new marine diesel engines

Tier 1 limits NOx emissions only, and applies to model years 2004 and later

Tier 2 limits NOx, CO, and PM, and applies to model years 2007 and later

Tier 3 “near term” emission standards for “existing” engines for most towboats, Tier 3 standards become effective in 2016

Tier 4 “long term” emission standards for “newly-built” engines mandates high-catalytic after-treatment application of high efficiency after technology for most of our towboats, Tier 4 standards may become effective in 2016

Growing opportunities for dual-fuel and gas-diesel engines in land and marine power markets have stimulated designs from leading medium speed and low speed enginebuilders. Development is driven by the increasing availability of gaseous fuels, the much lower level of noxious exhaust emissions associated with such fuels, reduced maintenance and longer intervals between overhauls for power plant.

A healthy market is targeted from floating oil production vessels and storage units, rigs, shuttle tankers, offshore support vessels and LNG carriers.

Valuable breakthroughs in mainstream markets have been made since 2000 with the specification of LNG-burning engines for propelling a small Norwegian double-ended ferry (Mitsubishi high speed engines), offshore supply vessels and a 75 000 cu.m. LNG carrier (Wärtsilä medium speed engines).

Natural gas is well established as a major contributor to the world’s energy needs. It is derived from the raw gas from onshore and offshore fields as the dry, light fraction and mainly comprises methane and some ethane. It is available directly at the gas field itself, in pipeline systems, condensed into liquid as LNG or compressed as CNG. Operation on natural gas results in very low emissions thanks to the clean-burning properties of the fuel and its low content of pollutants. Methane, the main constituent, is the most efficient hydrocarbon fuel in terms of energy content per amount of carbon.  Wärtsilä’s dual-fuel (DF) four-stroke engines can be run in either gas mode or liquid-fuelled diesel mode. In gas mode the engines work according to the lean-burn Otto principle, with a lean premixed air-gas mixture in the combustion chamber. (Lean burn means the mixture of air and gas in the cylinder has more air than is needed for complete combustion, reducing peak temperatures). Less NOx is produced and efficiency increases during leaner combustion because of the higher compression ratio and optimized injection timing. A lean mixture is also necessary to avoid knocking (selfignition).

Marine engine designers in recent years have had to address the challenge of tightening controls on noxious exhaust gas emissions imposed by regional, national and international authorities responding to concern over atmospheric pollution.

Exhaust gas emissions from marine diesel engines largely comprise nitrogen, oxygen, carbon dioxide and water vapour, with smaller quantities of carbon monoxide, oxides of sulphur and nitrogen, partially reacted and non-combusted hydrocarbons and particulate material. Nitrogen oxides (NOx)—generated thermally from nitrogen and oxygen at high combustion temperatures in the cylinder—are of special concern since they are believed to be carcinogenic and contribute to photochemical smog formation over cities and acid rain (and hence excess acidification of the soil). Internal combustion engines primarily generate nitrogen oxide but less than 10 per cent of that oxidizes to nitrogen dioxide the moment it escapes as exhaust gas.

Sulphur oxides (SOx)—produced by oxidation of the sulphur in the fuel—have an unpleasant odour, irritate the mucus membrane and are a major source of acid rain (reacting with water to form sulphurous acid). Acid deposition is a trans-boundary pollution problem: once emitted, SOx can be carried over hundreds of miles in the atmosphere before being deposited in lakes and streams, reducing their alkalinity.

Sulphur deposition can also lead to increased sulphate levels in soils, fostering the formation of insoluble aluminium phosphates which can cause a phosphorous deficiency. Groundwater acidification has been observed in many areas of Europe; this can lead to corrosion of drinking water supply systems and health hazards due to dissolved metals in those systems. Forest soils can also become contaminated with higher than normal levels of toxic metals, and historic buildings and monuments damaged.

Particulate matter (PM) is a complex mixture of inorganic and organic compounds resulting from incomplete combustion, partly unburned lube oil, thermal splitting of HC from the fuel and lube oil, ash in the fuel and lube oil, sulphates and water. More than half of the total particulate mass is soot (inorganic carbonaceous particles), whose visible evidence is smoke. Soot particles (unburned elemental carbon) are not themselves toxic but they can cause the build-up of aqueous hydrocarbons, and some of them are believed to be carcinogens. Particulates constitute no more than around 0.003 per cent of the engine exhaust gases.

Noxious emissions amount to 0.25-0.4 per cent by volume of the exhaust gas, depending on the amount of sulphur in the fuel and its lower heat value, and the engine type, speed and efficiency.

De-NOx technology options are summarized as follows:

The primary NOx reduction measures can be categorised as follows:

-Water addition: either by direct injection into the cylinder or by emulsified fuel.

- Altered fuel injection: retarded injection; rate-modulated injection; and a NOx-optimized fuel spray pattern.

- Combustion air treatment: Miller supercharging; turbocooling; intake air humidification; exhaust gas recirculation; and selective non-catalytic reduction. (Miller supercharging and turbocooling are covered in the Pressure Charging chapter.)

- Change of engine process: compression ratio; and boost pressure.

The basic aim of most of these measures is to lower the maximum temperature in the cylinder since this result is inherently combined with a lower NOx emission.

MARPOLAnnex VI choong

Below courtesy of CATERPILLAR USA


Below courtesy of Watsila
Watsila IMO Tier III



Below courtesy of Watsila
Watsila Emission AAA

More on Drilling Jack-up and some installations on board

The first step in the jack-up rig design is the definition of its configuration. This is based on operational and economic requirements and past design experience. Decisions made at this stage have a significant impact on the behaviour of the structure. The geometry of the configuration developed should have the necessary capacity to accommodate needed equipment, preload tanks and quarters. Preliminary estimates of weights should be made and a naval architect should assess the configuration for the “afloat” mode of the jack-up rig. A configuration for the legs should be developed. The system for connecting the legs to the hull so as to achieve efficient moment transfer should be chosen. A classification society should also be chosen [American Bureau of Shipping, 2001; Det Norske Veritas-Rules for Classification of Mobile Offshore Units]. A preliminary assessment should then be made to ensure that the chosen configuration complies with the requirements of the chosen classification society. After this, the basic design can be developed. The efforts of the structural engineer are important from this stage on. Hull scantlings are the individual elements that makeup the structure.

Due to the numerous complexities associated with jack-ups, it should be remembered that a structural analysis would be based on a number of simplifying assumptions and approximations. Though software is available to execute a non-linear dynamic analysis, the designer may opt for a simple static analysis using wave forces generated from a hydrodynamic analysis applying a linear wave theory (Such as the Stoke’s Fifth Order Potential Wave Theory) to a hydrodynamic model generated for this purpose.

The following steps should serve as a general guideline for the analysis of a jack-up platform:-

Define the environment including water depth, wind speed, wave (type, height, period) and current velocity and its variation with depth. This can be a location specific environment (North Sea, Persian Gulf) or a world wide criteria. The worldwide criterion is a reference benchmark that does not necessarily reflect any particular location. Some of the storm parameters (100 knot wind) are defined per code or classification authority or refer to API.

The results of these environments are then used as reference for the actual unit location. With the exception of very heavy loads (such as cantilever, transom and hold-down reactions, heliport support members, etc.), this may be accomplished by summing all the equipment weight on a deck, a proportion of the variable load on that deck and dead load and distributing this load uniformly over the entire deck. This may be done for all decks. Loads from the drill floor may be applied as concentrated forces at appropriate locations. Usually, the weight is assumed to be balanced equally among the three legs. This is normally achieved by moving the liquids among the various tanks to reach a balanced condition.

Generate a hydrodynamic model of the jack-up platform. This may be a simple model consisting of three “stick” elements that have the same hydrodynamic properties as the trussed leg. The ideal source of the drag values of the unit would generally be determined via wind tunnel models. This takes into account the actual geometry of the unit and the effects of shielding. Usually the product of these studies is a single drag value for the legs and hull. The main problem with this source of parameters is cost and time.

Generate a Global Structural Model: a typical finite element analysis model of a jack-up platform structure and usually the length of leg that should be used in the modelling for a given water depth. For a jack-up platform whose legs have independent spud can foundations, the legs are usually assumed to be pinned at a depth of about 10 ft below the mudline. For a mat supported jack-up, the structure of the mat may be modelled using plate elements and the legs could be fixed to this structure. Per the ABS Rules [American Bureau of Shipping, 20011, the minimum crest clearance to be provided is 4 ft (1.2 m) above the crest of maximum wave or 10% of the combined height of the storm tide plus the astronomical tide and height of the maximum wave crest above the mean low water level, whichever is less between the underside of the unit in the elevated position and the crest of the design wave.

Spud Cans

This is the most common type of jack-up platform foundation in use. Spud cans typically consist of a conically shaped bottom face. The purpose of a spud can is to transfer the jack-up leg loads into the seabed below. The structure of the spud-can should thus have the capacity to resist the resulting shear and bending stresses exerted on it by the leg and the foundation soils. To determine the maximum force on a spud can during the design phase, the total weight of the upper hull during the worst design storm condition and its center of gravity is first established. This weight is then distributed over all the legs of the jack-up platform. From the applied environmental forces, the overturning moment is determined next. The direction of this overturning moment should be so as to cause the maximum compressive force on one leg. An appropriate load factor should then be applied to this force. The area of contact between the spud can and the soil should be sufficient for the weakest chosen soil condition to support this force.

Other criteria that are applied to design the structural strength of the spud can are:

Assume that the entire reaction acts as a concentrated load on the tip of the spud can.

Assume that the entire reaction acts on a circle centred on the tip of the spud can, whose radius is (i) %, (ii) %, (iii) 3/4 and (iv) 1 times the equivalent radius of the can.

The lower plating should be designed for the resulting distributed loads. Spud cans are usually designed to be flooded during operation. To facilitate access to the inside of the can, during the floating condition of the jack-up platform, vents may be provided to a certain height above the top of the can. The upper plating should be designed for a hydrostatic head corresponding to the height of this vent in case the can is not flooded.

Legs

Trussed legs are the most common type on modern jack-up rigs, the other type being cylindrical legs. Legs are subjected to the following forces:

(1) Elevated condition:
(a) Compression forces due to gravity loads on the hull.
(b) Compression forces due to the reactive couple caused by overturning moments on the jack-up.
(c) Bending moments at the hull due to the horizontal displacement of the hull and the moment connection between the leg and the hull.
(d) Horizontal forces on the leg due to wave, current and wind action.
(e) Bending moments due to P-A effect on the leg.
(f) High local stresses due to force transfer and from the pinions. “rack chocks, hull upper and lower guides”.
(2) Afloat condition:(a) Gravity loads on the leg.
(b) Wind force.
(c) Inertia forces due to vessel motions.
(d) Restraining reactions from guide units or other locking devices in the hull that create high moments in the leg.
(e) Fatigue causing cyclic stresses in the lower bays of the legs due to the constant pitch and roll motions of the floating vessel.