From the movie Animal House, "Fat, drunk, and stupid is no way to go through life ...".
While the LCS certainly seems to have been designed by drunk and stupid people, it now appears that the LCS is fat, also.
Weight growth margins have long been a known deficiency of the LCS. While fairly well documented in the Freedom variant, the magnitude of the problem in the
variant has been less clear and many observers have assumed that the Independence variant had little or no weight problem. Freedom, you may recall, had to have "water wings" (buoyancy tanks) welded on to the stern and they have been incorporated into subsequent ships of the class. Independence
Stability has also been a known problem for the Freedom class. Module swap tests revealed that simply shifting normal container weights caused the ship to reach its allowable incline limits.
A new GAO report now sheds some light on the weight situation and provides some actual data (1).
The report notes that the ships have exceeded their expected weights with resulting impacts on performance.
"Weight growth occurred on the first four LCS seaframes, which affected the capabilities of both Freedom and
variant seaframes. This situation has led the Navy to accept lower than minimum requirements on two delivered seaframes (LCS 1 and 2) in endurance and sprint speeds, respectively." Independence
From the report, affected performance parameters include,
• sprint speed
• navigational draft
• service life allowance for weight
The report notes that range has already been significantly reduced,
"In 2009, the Navy received authorization from the Joint Requirements Oversight Council to reduce LCS’s original endurance requirement, which was a 4,300-nautical-mile range when operated at a speed of 16 knots, to the current endurance requirement. [ed: 3,500 nm at 14 kts]"
The report states that the service life allowance (
SLA) weight is specified as 50 tons. This is the required weight growth margin for future equipment additions to the ship. Only two of the first six ships have met their specifications and the rest have missed by a substantial margin. Listed below are the individual ships, their target SLA (tons) and their actual margin (tons).
LCS-1 50 26
LCS-3 50 156
LCS-5 50 67
LCS-2 50 -16
LCS-4 50 16
LCS-6 50 31
Only LCS-3 and -5 have met their
SLA margins. The rest have missed by a substantial amount. Interestingly, the variant seems to be significantly worse than the Freedom, contrary to what most people thought. Independence
The report also provides data on the ship's full load weights (crew, stores, module) compared to their naval architectural limits (max allowable weight). Full load weights that exceed the naval architectural limit risk damaging the ship due to excessive strains and stresses imposed by the excess weight. Here are the full load weights as a percentage of the naval architectural limits. The closer the ship is to 100%, the more the strain and stress. Values over 100% risk damage.
None of the ships have any significant operational weight margins and LCS-2 actually exceeds the allowable limit.
The report indicates that the Navy will operate LCS-2 at reduced fuel loads so as to reduce the weight to acceptable levels. As equipment or additional crew (remember that the Navy has increased the core crew from 40 to 50 and will probably add more) is added, the remaining ships may also have to be operated at reduced fuel loads.
Further, the Navy is addressing weight concerns in the
variant by designing reductions in fuel capacity (hence, range) in future ships of the class, Independence
"... the Navy is developing design modifications for
variant seaframes to reduce fuel capacity—estimated to total over 100 metric tons—in order to restore service life allowances." Independence
The report notes that various ships have failed to meet their range and speed requirements due to excess weight. This, after the range spec was already substantially reduced!
The specification for sprint speed is 40 kts but the report notes,
"LCS 2 contractor officials told us that the calculated speed in the full load condition LCS 2 is 36.5 knots."
Thus, the shining characteristic of the LCS, speed, which negatively impacts so much of he ship's design, is not even being met. Yikes! That's a double hit.
As if all this isn't bad enough, the service life allowances not only aren't being met but it turns out that the allowances aren't even up to industry standard. As stated in the report,
"Complicating the weight growth on early LCS seaframes is the fact that LCS requirements for service life allowances already fall short of the growth margins called for under Navy and industry recommended practice."
Standards for other ship classes range from a low of 5% margin for amphibious ships to 10% for surface combatants. The LCS target margin is only 1.5% to begin with. So, in addition to not meeting the margin, the margin was ridiculously low to begin with.
Excessive weight also affects stability as demonstrated with the Freedom module swap tests. Other ship classes have stability margins (distance the vertical center of gravity can shift in response to weight growth before stability is compromised) of 0.3 m for amphibious ships to 0.8 m for carriers. The LCS stability margin is 0.15 m - again, a very low value compared to other classes.
Note that the current weights are with the very stripped down version of modules currently being procured. As the modules gear up to their target requirements, the module weights will increase and this is already impacting module design and will get worse with time. As noted,
"According to Navy officials, future additions to mission packages ... will be offset by removing existing systems ..."
Module weight limits may result in modules being developed in variations. For example, the MCM module may not have all its equipment in a single module. Instead, it may have to field variations of the module which have subsets of MCM equipment to meet weight limits.
What does all of this mean? Well, beyond the obvious conclusion that the LCS design is a poor one, one of the major selling points of the LCS was that it would represent the ultimate in flexibility and adaptability over its service life. This would be the ship that could be adapted and modified to accommodate future needs, thus keeping it relevant over its entire life. Unfortunately, the reality is that the ship is severely constrained by weight issues and has little or no room for growth. Module improvements - and let's be honest, improvements always mean bigger and heavier - will have to be severely restricted by weight limits. Anything added to the ship will have to compensated by the removal of an equivalent amount. This pretty much eliminates flexibility as a characteristic of this class.
Amazingly, the Navy is about to embark on this same weight limited path with the Burke Flt III. Talk about an inability to learn a lesson!
(1) Governement Accountability Office, "LITTORAL COMBAT SHIP - Additional Testing and Improved Weight Management Needed Prior to Further Investments", GAO-14-749, July 2014