Why doesn’t the US Navy build big?
Below is my analysis of why warships should be really big. In reality, they are not. What part of the analysis is wrong or what factors are not considered?
A larger warship has more margin for growth, can operate un-resupplied for longer, can travel farther faster, can supply more electrical power and is more damage tolerant. If the operational requirements are held constant (don’t try and cram more into the bigger ship), the incremental acquisition cost of going large should be relatively small. The operational costs of the bigger ship can actually be less. A larger size allows for simpler / heavier systems such as dual direct drive diesels. It also allows a reduced focus on weight / volume / power minimization to allow less expensive development of similar capabilities.
The proposed Go Big ship - 125,000 tons, 30+ knots, 2 x 65MW two stroke diesels, estimated range of 70,000 NMI at 20 knots with 12,500 ton fuel load - 360m length x 49m beam x 12m draft
In an extreme case, could a 10,000 ton DDG-51 be replaced at a reasonable cost by a 125,000 ton Go Big destroyer?
DDG-51 – 10,000 tons, 30+ knots, 4400 NMI at 20 knots - ~2billion 155mx20mx9.3m
The primary costs of the DDG-51 are acquisition ($2 billion) and operation ($70 million /year). Assuming a 30 year life cycle, that is roughly $4.1billion. A Maersk Triple E is bigger (~200,000 tons loaded) and simpler, but only costs $200M. So, it is not the cost of steel or large assembly that drives costs, but the complex military hardware a DDG-51 carries. Let us have the Go Big destroyer carry exactly the same military hardware, but be built on a much larger frame and use the heavier, but more efficient 2 stroke diesels. As an approximation we will add the cost of the Triple E to the DDG-51 - $2.2billion. It should be less as there is overlap in equipment between the two vessels and the proposed Go Big destroyer has a loaded displacement only 60% of the Triple E.
Operations are the other major cost. The DDG-51 $70 million yearly cost can be broken into 3 major categories – personnel (~300 crew) $40M , fuel - $10M, maintenance/upgrade - $20M/year. The Triple E has a crew of 22, so again size is not the driver, but system complexity. By being bigger, full supplies can be carried on board (fuel, food, water, ordinance, etc.) so fewer specialists are needed for distillation, frequent UNREP, etc. Some automation would be carried over to achieve closer to a DDG-1000 crew size (123 crew). Finally, merchant marines would be part of a mixed crew to support non-combat systems. The total crew size would be 200 ($27M /year).
Fuel is another large cost - $10M/year. The larger ship while 12.5 times as heavy only requires 2.5 times as much force to push through the water at the same speed. Being able to carry more than a full deployment of fuel avoids the cost of navy fuel tankers which accounts for 20% of the DDG-51 fuel cost. The more efficient 2 stroke diesels would use 25% less fuel. Finally, bunker fuel rather than MGO would be used to reduce costs another 50%. All told $10M * 2.5 * 0.8 * 0.75 * 0.5 = $7.5M.
Maintenance is the final category. It again appears to be primarily driven by system complexity. An approximation of the DDG-51 maintenance cost + a larger container ship maintenance cost is used - $23M/year. This is an area that could use further reductions.
Lifecycle costs for the Go Big destroyer would be $2.2B + 57.5M*30 = $3.9B
As long as similar operational requirements are maintained it seems that a much larger ship can fulfill the role of the smaller DDG-51 for a lower total cost while providing significant advantages.
It makes even more sense to Go Big (to 125K tons) for larger ships such as the USS America (LHA-6) – 45,000 tons, 22 knots, estimated range of 20,000 NMI at 20 knots with 4500 tons fuel - 257mx32mx8m
But, warships (other than the biggest aircraft carriers) are not built anywhere near the proposed size. What part of the analysis is wrong or what factors are not considered?
Below is my analysis of why warships should be really big. In reality, they are not. What part of the analysis is wrong or what factors are not considered?
A larger warship has more margin for growth, can operate un-resupplied for longer, can travel farther faster, can supply more electrical power and is more damage tolerant. If the operational requirements are held constant (don’t try and cram more into the bigger ship), the incremental acquisition cost of going large should be relatively small. The operational costs of the bigger ship can actually be less. A larger size allows for simpler / heavier systems such as dual direct drive diesels. It also allows a reduced focus on weight / volume / power minimization to allow less expensive development of similar capabilities.
The proposed Go Big ship - 125,000 tons, 30+ knots, 2 x 65MW two stroke diesels, estimated range of 70,000 NMI at 20 knots with 12,500 ton fuel load - 360m length x 49m beam x 12m draft
In an extreme case, could a 10,000 ton DDG-51 be replaced at a reasonable cost by a 125,000 ton Go Big destroyer?
DDG-51 – 10,000 tons, 30+ knots, 4400 NMI at 20 knots - ~2billion 155mx20mx9.3m
The primary costs of the DDG-51 are acquisition ($2 billion) and operation ($70 million /year). Assuming a 30 year life cycle, that is roughly $4.1billion. A Maersk Triple E is bigger (~200,000 tons loaded) and simpler, but only costs $200M. So, it is not the cost of steel or large assembly that drives costs, but the complex military hardware a DDG-51 carries. Let us have the Go Big destroyer carry exactly the same military hardware, but be built on a much larger frame and use the heavier, but more efficient 2 stroke diesels. As an approximation we will add the cost of the Triple E to the DDG-51 - $2.2billion. It should be less as there is overlap in equipment between the two vessels and the proposed Go Big destroyer has a loaded displacement only 60% of the Triple E.
Operations are the other major cost. The DDG-51 $70 million yearly cost can be broken into 3 major categories – personnel (~300 crew) $40M , fuel - $10M, maintenance/upgrade - $20M/year. The Triple E has a crew of 22, so again size is not the driver, but system complexity. By being bigger, full supplies can be carried on board (fuel, food, water, ordinance, etc.) so fewer specialists are needed for distillation, frequent UNREP, etc. Some automation would be carried over to achieve closer to a DDG-1000 crew size (123 crew). Finally, merchant marines would be part of a mixed crew to support non-combat systems. The total crew size would be 200 ($27M /year).
Fuel is another large cost - $10M/year. The larger ship while 12.5 times as heavy only requires 2.5 times as much force to push through the water at the same speed. Being able to carry more than a full deployment of fuel avoids the cost of navy fuel tankers which accounts for 20% of the DDG-51 fuel cost. The more efficient 2 stroke diesels would use 25% less fuel. Finally, bunker fuel rather than MGO would be used to reduce costs another 50%. All told $10M * 2.5 * 0.8 * 0.75 * 0.5 = $7.5M.
Maintenance is the final category. It again appears to be primarily driven by system complexity. An approximation of the DDG-51 maintenance cost + a larger container ship maintenance cost is used - $23M/year. This is an area that could use further reductions.
Lifecycle costs for the Go Big destroyer would be $2.2B + 57.5M*30 = $3.9B
As long as similar operational requirements are maintained it seems that a much larger ship can fulfill the role of the smaller DDG-51 for a lower total cost while providing significant advantages.
It makes even more sense to Go Big (to 125K tons) for larger ships such as the USS America (LHA-6) – 45,000 tons, 22 knots, estimated range of 20,000 NMI at 20 knots with 4500 tons fuel - 257mx32mx8m
But, warships (other than the biggest aircraft carriers) are not built anywhere near the proposed size. What part of the analysis is wrong or what factors are not considered?