Margins & Allowances Estimation

• uncertainties in the calculations and weights used to estimate the vessel's lightship weight,
• potential design changes that will occur during construction,
• weight growth during detailed design and construction that can occur as more detailed design is performed and better estimates & calculations are undertaken,
• potential revisions to the contract during design and construction, and
• possible additional equipment etc that the government may want to add to the vessel during design and construction, etc.

1. Developmental designs with a high level of uncertainty
2. New concept design with some significant level of uncertainty
3. Designs similar to existing designs but with major changes and an associated level of some uncertainty
4. Designs similar to existing designs with minor changes and only a small level of uncertainty,
5. Follow-on designs with only minor changes and almost no uncertainty

• if you were trying to recreate an existing design, I would define it as a Category 5 vessel,
• if you were trying to investigate a relatively simple modification to an existing design, such as investigating fitting an alternate existing weapons, sensor, or propulsion engine, etc or if you were trying to investigate a design that, while not being directly derived from an existing design, it is still very conventional, and uses existing weapons, sensors, and propulsion engines, etc I would also define these as Category 4  vessels,
• if you were trying to investigate a more complex modification to an existing design, such as investigating fitting a limited number of alternate not currently existing/developmental gun sensor, or propulsion engine, etc or if you were considering fitting a completely new propulsion plant, or if you were trying to investigate a design that, while not being directly derived from an existing design, it is still very conventional, but uses a limited number of not currently existing/developmental weapon, sensor, or propulsion engine, etc I would also define these as Category 3 vessels,
• If you were trying to investigate any other form of conventional displacement monohull that includes a significant number of not currently existing/developmental gun sensor, or propulsion engine, etc or some form of radical/new propulsion plant, then I would define these as Category 2  vessels, and finally
• If you were trying to do something else, like a multihull or an all aluminum or composite hull larger than any previously built vessel etc, for now I'd guess that would probably best be described as a Category 1 vessel.

• Recreating vessels like the FFG7, DD963, DDG51, & CG47 etc would all be Category 5  type designs
• Recreating the FFG7 but substituting a 57mm or 127mm gun for the 76mm gun, or a VLS for the Mk13 launcher would be a Category 4  type design.  Similarly, investigating a totally new conventional monohull design, outfitting with an existing gun (like the 127mm Mk45) and existing sensors (like the SPS-48 and SQS-53 sonar), and existing gas turbines (like the LM2500) would also probably best be considered a Category 4  type design.
• Recreating the DDG51 but substituting a weapon that is still under development or which was only ever developed as a prototype etc (like the 203mm MCLWG etc) would probably be a Category 3 design.  Similarly, investigating a modified repeat of the DDG51 with an alternate power plant based on the MT30 gas turbines would also probably best be described as a Category 3 design, as would a completely new (but conventional monohull) with only a limited amount of developmental equipment (such as if I were to substitute LM2500+ or MT30 gas turbines into the sample Category 4  vessel noted above)
• Trying to design a relatively conventional monohull (similar to the DDG51) but outfitted with SPY3, the AGS gun, PVLS missile launchers, and an integrated electric drive would probably best be described as a Category 2 type design
• For now, trying to develop a design like the DDX or the trimaran LCS would likely be Category 1 designs (for the monohull LCS I'd guess that you should probably consider it part way between a Category 1 and Category 2 design) 

• HIGH Risk - There is a high possibility that the design might not meet safety limits (subdivision, strength, service life allowances), which might result in the need to redesign all or part of the ship during detailed design and construction which could significantly impact the overall cost and building schedule for the vessel.  As such, extreme weight control measures would be required.
• MODERATE Risk - For vessels falling in this category it is expected that weights can be controlled during detailed design and construction by use of an effective weight control program that would involve incentives, Not-to-Exceed values, and other risk mitigation measures.
• LOW Risk - Vessels falling into this category are considered relatively safe designs with very little uncertainty where weight growth can be controlled during detailed design and construction by applying standard weight control and reporting procedures.

• the potential need to use a lot of lighter weight materials and equipment to keep weights down,
• the need to conduct alot of additional analyses to see where the use of this lighter weight materials and equipment would be suitable in place of more conventional stuff,
• a higher overall material (and potentially labor) cost for the design as the lighter weight materials and equipment would likely be more costly than more conventional stuff, as well as
• the potential impacts to the design and building schedule if it is found necessary to redesign a large amount of the ship to implement lighter weight materials and equipment, etc.

For the purposes of putting together a design evaluation tool I'd suggest prohibiting the use of margins that would result in the design falling into the HIGH Risk category (for now).

With respect to designs that fall into the MODERATE Risk category, as noted above it is expected that weight growth could be controlled during detailed design and construction so that providing enough margins for the vessel to fall within this category, is probably acceptable, but there is probably some additional costs associated with it (as it will probably require the use of at least some ligher weight materials and equipment and/or additional engineering, etc).

If a vessel design has enough margins to fall into the LOW risk category I'd suspect that there probably shouldn't be any appreciable additional costs, etc associated with that design.

As such, for the design evaluation tool I would suggest the following:

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