Let me qualify my position on this (not that anyone cares.. :)) I think I've been trying to look at all contingencies, ie hot and tame environments I do think that it can be built, but I have reservations about a mass limitation I don't think that it is practical to come up with a metallic version of Staten Island, Diego Garcia etc.. Within very tight parameters, at an engineering level I think it is possible. My view has always been, is this the best way to invest effort, park weaponry and logistics etc... for the required task. I still think that it is cost, strategy and tactically ineffective.

The problem in evaluating mobs lies in restricting the analysis to a comparison to an aircraft carrier built like an offshore oilrig. The concept I'm talking about is a self propelled 1000 foot ship, with extreme beam and draught, that can be assembled lego style. Assume a 6 ship configuration for a particular mob. One ship is primarily a giant fleet supply ship with associated foundries, machine shops and techology centres. One is primarily a giant personnel transport ship with room for all the required support equipment that the personnel require. One is a giant c4 ship with a large health facility and training/recreation. One is a giant heavy sea lift ship that carries it's own transport ships internally (to transport personnel, freight, weapon systems or antisub sytems in whatever mix seems appropriate for the mission). One is a giant heavy air lift ship that has hangar space and support for major aircraft (whether freight, passenger or bomb trucks). One is a giant cargo carrier. That leaves one to be selected for it's ability to emphasize a desired capability. And, of course, a 6 thousand foot runway. Each one has the ability to supply or be supplied by very large freighters on each side. Each one has very large storage capacity for supplies, fuel, equipment, and anything else you care to put in. Each one has it's own antisub helo squadron, it's own squadron for cap purposes, it's own missile system and it's own surface weapons. Each one serves a vital and perhaps irreplaceable function in addition to having more self defense than a carrier. Each one, on it's own is a very valuable asset in ways that a carrier cannot be. Carriers have traded size and flexibility for speed and manouverability. Mobs trade speed and manouverability for size and flexibility. Mobs are not simply big carriers. They are something else entirely which is so big that they also have greater air capacity than several carriers in additon to their other functions. They are cheaper than carriers because they serve other functions which are valuable. They can be put to good use in whole range of situations where your carriers are just floating around with nothing to do. Unlike carriers their versatility is such that their non military use would prove more valuable than the few times when they would actually be assembled for military strikes. You can assemble it offshore from a particular country because you intend to bomb it to pieces, because you want to invade it with lots of troops, because you want to go in and rescue thousands of your citizens, because you want to send in massive aid to deal with catastrophe, because you want to provide a functioning air and seaport close to a disaster area, because you want to provide a nbc response base for any number of calamitous situations or you can just send in one of the ships on it's own with it's particular ability to do something which few if any other ships can do. All a carrier can do is carry it's own air defense with an additional small amount of strike aircraft. It has no non military use and few military purposes. They are vulnerable, expensive and limited in their respone. A carrier battle group is very visible on the surface, from space and by any number of sensing technologies. It's greater speed is a defensive factor only in relation to submarine attacks to which it is extremely unlikely to survive if the enemy is successful. With the next generation of longe range, super high speed, wake homing torpedoes sent up from the bottom by remote control, a carriers speed will be as irrrelevant against torpedoes as it is against missiles. In an earlier post I asked that given the mob's capacities in excess of a half dozen carriers why wouldn't you provide the mob with the escort of 3 carrier battle groups. I didn't express myself clearly. I didn't mean that you would provide the carriers, just the escorts. You could keep the carriers back at home base in reserve since they could do far less than the mob at much greater risk to themselves. I am surprised at how sanguine everybody is about the challenge involved in building such ships that, when assembled together, would function without difficulty. It is not an oil rig. It is self propelled. It has to link up with another equally large ship. It has to be sufficiently stable to provide a surface for a runway. It has to be able to disconnect reasonably quickly. Bringing objects that size into contact with each other while at sea strikes me as an example of an irresistable force meeting an immovable object. However, I have neither experience, training or judgement in such matters!

gf0012-aus, someone hasn't quite been understanding whats been said earlier ;) (Note I'm the same guy who posted under hybrid way back in the thread). Let me explain something about the MOB concept. First off it isn't meant to go directly under fire, CVN's and their battle groups do no such thing either..they have a combat radius of 500-1000km usually and the MOB will have no less a combat radius from its target. In fact because of its large assembled size it can have a combat radius between 2-3 times that of a CBG. Second you're all getting something wrong about assembly times. Look up the latest tables especially on the Becthel modular arrangements, this type of platform can be connected in a few hours if necessary, the only problem they're trying to solve is wave oscillation over the full length of the vessel. Oil rig technology is being used via the idea of semi-submersible hulls. A MOB is NOT an aircraft carrier. What it IS however is logistics platform that is a few steps down from a land base when no such base is available. So yes you're going to have a lot of escort firepower for such, there also most likely wont just be one MOB structure. More importantly its a lot easier to defend a stationary structure than a moving one...think defense nets and circles ;) If we can get the oscillations problems hammered out expect MOB to be out around 2010.

And for what purposes? First, it's not realistic to expect a MOB to handle 747s as I've seen suggested. Maybe a C-17, but probably nothing bigger than a C-130 Hercules. On the other hand, a MOB program might just encourage the development of a more capable successor to Hercules, which has been in service for almost 50 years now. Second, it's comparing aplles and oranges when mentioning how many "cruise missile equivalents" a MOB would cost. A MOB would not be used as launching platform for cruise missiles. Surface ships, submarines and B-52s do that job just fine already. As I see it, a MOB would be used as a forward staging platform for strike aircraft, Marine ground forces, Special Forces and possibly future (light) AirMechanized Army forces. It would obviously be useful for humanitarian and disaster relief as well, just as the intimidating effect of a large structure within striking distance of a potential adversary should not be underestimated. So yes, it could and probably would be very useful, but that said I believe more or less the same could be accompliced with a new generation of bigger, but slower and simpler (not to mention, cheaper) aircraft carriers. I believe the number of deployable "decks" matters far more than how many aircraft each deck can accommodate/operate. If you have an abundancy of relatively cheap "decks" you can always send an extra to a "hotspot" if need be. I think a continuation of the current crop of CVNs as well as initiation of a MOB program would swallow so many ressources that the USN will eventually end up with FEWER decks, rather than MORE decks! :(

Would the "still on the drawing board" Russian Tri-maran carriers be an example of an early MOB? If the US had even one or two of those it could serve as a mini-sub carrier, aircraft carrier and cruise missile platform all in one. Maybe a next generation MOB could have a large ABM/anti satellit laser as well.

Don't know re how alive the tri-carrier design is. But I will be seeing this bloke at the Pacific 2004 forum (about 4 months away). My intention was to ask again about it as it seemed to be an interesting concept. There are trad shipbuilders who said it was not possible as the design breached deck height to draught ratios (or something similar) It wasn't exactly a light weight conversation and I was getting confused after 5 minutes (which was probably his way of extricating himself from further conversations about it)....

My understanding of the mob concept is what Valiant describes. I consider the notion of joining the units together to be more than a trivial operation. I have a small amount of experience in trying to join seaborne objects together in a sea state. Objects the size of semi submersible oil rigs or even larger would require a sizable operation to join together. It is less of an exaggeration to say it could take a few days than it is to say it would take only a few minutes. Momemtum can be a wonderous thing to behold. Since the purpose of joining them is to provide a continuous runway they would need pretty close to perfect alignment in three dimensions all the time. Such alignment would require the inclusion of trim adjustment to be accomplished. Submariners on the board could comment on the difficulty of maintaining almost perfect trim on a vessel that size relative to another equally large vessel. I'm not saying it can't be done. I am saying I need to be convinced it can be done quickly, reliably, safely and predictably under most conditions. Separation, on the other hand, would be relatively simple and should take almost no time at all.

I could probably take a stab at it and try to guess why a trimaran wouldn't make a good "full" carrier, however I'll add this caveat that I am NOT comparing it to a MOB structure. First with a trimaran or even cat design you're designing multiple hulls, these have to be designed to exacting standards and at the same time linked to the centerline hull correctly. When you consider ships of the Nimitz class size which is what we are looking at, this is indeed a very large vessel to build which NO ONE has any experience building and no one has experience with regarding the stresses involved in the various points (especially where they are joined to the centerline hull). Making a smaller vessel of up to 35,000 tons is on the other much easier especially if we keep the length to under 200 meters, this reduces complexity, cost and build time. Next is the ship's superstructure, in the case of a "full" carrier you want it to be off center, and tall enough to see where you're going, if you can push the superstructure somewhat forward as well without compromising stability then thats an added bonus since you'll avoid any turbulence caused by said structure while landing. Another is possible reduced internal volume for a given tonnage or instability if an outrigger is damaged. In other words, the idea needs to be tested more thoroughly (I believe in the 1980s the US was pursuing this concept for a Nimitz class vessel but for some reason was shelved, I would guess it may have something to do with the above reasons). For smaller vessels such as helicopter carriers and VTOL carriers as well as cargo freighters on the other hand this may be a good thing to look into.

Washington Daily News February 05, 2004 Basnight floats an OLF idea In-Depth Coverage By Bill Sandifer If it floats, is owned by the Navy and jet fighters land on it, it must be an aircraft carrier. Historically, that has been the case. However, a floating offshore platform fits the model with aplomb, as well. So says state Sen. Marc Basnight, D-Dare, Senate president pro tem. He's suggesting such a platform to break the outlying landing field logjam between North Carolina and the Navy. In a Jan. 23 letter to the state's congressional delegation, Basnight outlines his suggestion: "I ask that you encourage the Navy to explore what many believe is a legitimate alternative to the current OLF site: building an offshore platform for pilots to practice taking off and landing the Super Hornets. An offshore platform in the Atlantic Ocean, or perhaps in Pamlico Sound, is a viable option that deserves careful review. In fact, this suggestion was raised earlier as a potential alternative to a land-based OLF, but the possibility barely even received a mention in the Navy's final environmental impact statement. ... "(A)n offshore platform would improve pilot safety by reducing the risk of costly bird collisions and by providing a more realistic practice area. Moreover, it would not cause further economic damage in one of North Carolina's most economically depressed areas. And it would avoid putting local residents in danger of a jet crashing into a home, a school, or another building. "By contrast, the current OLF site choice would have several extremely harmful effects in Washington County and in nearby Beaufort County. In all my years of public service, I can think of no proposal that has generated more united opposition than this one." A strategic concept The Navy is no stranger to offshore platforms. In 1996, the Office of Naval Research began work on Mobile Offshore Bases, or MOBs, yet another acronym to go along with OLF. The Navy even has devoted a Web page to explaining the MOB in voluminous detail, laced with enough technical information to satisfy a scientist. But both concepts share more than just a three-letter designation. In January 1998, a Norwegian firm that developed floating oil rigs capable of withstanding the brutal conditions found in the North Sea, published the results of a $6 million feasibility study conducted for the Navy. "SeaBase has been conceived as the world's largest ever marine structure," states Aker Kvaerner's Web site. "Kvaerner's vision for the huge semi-submersible structure, the largest of its kind in the world, is 1,600 metres long and 140 metres wide, comprising three large-scale semi-submersible platforms, based on concepts derived from Kvaerners world-class experience in the design and construction of large structures for the offshore oil and gas industry. The three platforms are linked by two semi-buoyant flexible bridges. SeaBase will be capable of absorbing the motions of the high seas, and remain operational as a movable military base, even in severe weather. Facilities aboard SeaBase will include a runway capable of landing up to C-17 transport aircraft, and accommodations for up to 10,000 military personnel." From Navy concept to Kvaerner publication, the idea has created a stir. "The United States was interested in the idea of having a large mobile floating base that could be relocated anywhere in the world," writes Dr. Ronald Riggs, a University of Hawaii engineering professor. "It could be placed in international waters, where it wouldn't be subjected to other country's national laws, regulations, and restrictions." Riggs is among a number of engineers who have conducted research for the Navy. "Dr. Riggs and Dr. Ertekin's research led them to solving fluid and structural dynamics problems that these very long structures would face," states a UH Web page. "Their research for the U.S. Navy helped gain a better understanding of how multi-module structures would respond and behave in waves, which in turn will help engineers design a more intelligent structure." Riggs' and Ertekin's researched resulted in construction of a large, floating causeway that allows the Navy to off-load materials in areas where there is no shore access, contends the Web site. "We got good feedback for that particular product," writes Riggs. In January 2003, Navy engineers published a Web page devoted to MOB research. A list of other firms and organizations conducting that research and developing technology for the MOB concept reads like a who's who of Department of Defense contractors, including Boeing, McDonnell-Douglas and Bechtel National. Major universities, including MIT, also are researching the project. One firm conducting MOB research is well-placed with the Bush administration. Brown and Root, better known as KBR -- a firm alleged to have overcharged DOD for contract work in Iraq -- is a

The most recent edition of Proceedings has done an article on MOB, includes a feasability done by Maersk.