Comments And Analysis

A number of times I have been faced with, or asked about, the problem of whether to demothball and then refit, or to refit and then demothball a ship. As I have finally looked at the numbers, the question is discussed, and answered, here.

The Answer

First, for those who don't want to read through the discussion, the answer:
It is cheapest to demothball the ship, and then refit it. While the lowest in cost, this also means that the ship is available for service when the demothballing is complete, just in case it is needed immediately.

Why?

• When refitting a unit which is mothballed, you must pay normal maintenance during the refit.
• The cost of demothballing a unit is three times its monthly maintenance.
• The actual cost of the refit will be ignored, since it must be paid regardless of the order in which the work is performed.
• Let M_o = The monthly maintenance cost of the original design.
• Let M_n = The monthly maintenance cost of the new design.
• Let C_d = The total cost of the demothball then refit order.
• Let C_r = The total cost of the refit then demothball order.

The cost of refitting and then demothballing a unit would be: C_r = M_o + 3 x M_n
That is, the cost of one month of the old maintenance cost while it is being refitted, plus three times the new monthly maintenance cost to demothball the ship.

The cost of demothballing and then refitting a unit would be: C_d = 3 x M_o + M_n
That is, the cost to demothball the ship at three times its original monthly maintenance plus one month of the new maintenance cost while it is being refitted.

Assuming that the new version of any ship is more expensive than the previous version, then we know that:
   M_n > M_o

If we assume that:
   C_r > C_d
then,
   M_o + 3 x M_n > 3 x M_o + M_n
Subtracting M_o and M_n from each side of the equation gives:
   2 x M_n > 2 x M_o
Dividing by 2 leads to:
   M_n > M_o
Which we already know is true.

Therefore, if
   C_r > C_d
It is more expensive to refit the unit and then demothball it, than to demothball it first followed by a refit.

Of course we may note that the reverse will be true if the new version of the ship is less expensive than the previous version.

Example

Now, for a "real world" example from the MMoidverse Campaign.
A Valiant Fighter II class destroyer is to be reactivated and upgraded to a Valiant Fighter V class.

Design	TL	Design Layout	Cost	Maintenance
Valiant Fighter II	3	[3] Sx3Ax5ZH(I)(I)W(I)(I)W(I)D(I)WMg(I)LhQ [7/3]	391.0 Mc	58.7 Mc
Valiant Fighter V	5	[3] SAix9ZM1(I)(I)(I)Hs(I)DW (I)W(I)DLhQ(I)WMg [7/3]	444.0 Mc	66.6 Mc

To refit then demothball would cost:
   C_r = M_o + 3 x M_n = 58.7 + 3 x 66.6 = 258.5 Mc

To demothball then refit would cost:
   C_d = 3 x M_o + M_n = 3 x 58.7 + 66.6 = 242.7 Mc

To Play Comments

Updated 28 September 2000.