T20 Starship Armour Calculation Confusion

[Gruffty]

Could anyone please clarify how the bloody hell starship armour tonnage and cost is calculated in T20? I'm just a little confused by the way the rules on this are phrased - so forgive me if I appear a bit dense

1. The ship I'm building is 50,000 tons displacement.

2. The ship's TL is 13.

3. According to the Drives and Armor table (p.259) the "Armor Factoring" for 50,000 tons is "500".

4. The rules for armor (p. 268) state:

"To achieve the first layer of armor (Armor USP of 1), a ship must install twice as many armor units as the armor factor specified for the hull size and TL of the armor."

OK.....

So:

</font>

• 500 armor units*2=1000 armor units.</font>

</font>

• TL12-13 armor units are 2 tons per unit.</font>

Thus:

</font>

• 1000 armor units*2tons=2000 tons for a USP Armor factor of 1.</font>

Correct, so far? <you can always let me know if I'm going wrong somewhere.... >

</font>

• Base cost is Cr 300,000 plus Cr 200,000 per unit at TL 12-13.</font>

Right......

So, is that:

</font>

• (Cr 300,000 + Cr 200,000 = MCr 0.5)*1000 armor units = MCr 500 for a USP armor factor of 1?</font>

Or....
</font>

• Cr 300,000 +(Cr 200,000*1000 armor units = MCr 200) = MCr 200.3 for a USP armor factor of 1?</font>

Answers on used sterling notes to the usual address, please.................

 

[tjoneslo]

Armor cost is MCr200.3, the second calculation is correct. The number of armor units and mass is correct.

 

[far-trader]

Respectfully I have to disagree with you on the cost calculation tjoneslo. T20 ship building is really (for the most part) High Guard and in HG the formula is better expressed and includes an example. You add the KCr300 to the unit cost of KCr200 in this case and then mulitply by the number of units. So it should be:

(KCr300 + KCr200) 1000 Units = MCr500.0

IF the design sequence is supposed to match HG designs which seems the intent.

 

[mike wightman]

I agree with Dan.

And I also find the original High Guard formulae easier to use than the T20 "simplification"

 

[tjoneslo]

I respectfully disagree. Here are my reasons for thinking as I do.

Check the SDB: 200 ton hull is armor factoring of 2. TL 14 armor is 1 ton per unit, AR14 requires 15 units of armor or 15 tons. (correct so far). Cost is 0.3 + (0.1 * 15) or Mcr 1.8. Done the other way it's (0.4 * 15) or 6 Mcr. The worksheet for the SDB shows armor cost is Mcr 1.8.

The armoring for the Ship design and the vehicle design are done the same way, with the same confusing wording. So if starships are done one way, so should the vehicles. And all the vehicles I've check do it the second way.

If your way is correct, why isn't the rule worded as : Armor costs Kcr 500 per unit? If this is correct, it's easier and simpler.

The other reason I suggest it's done the other way is the order of presidence in math operators. A formula of the form : x + y * z is interpreted as x + (y * z). At least, that's the way I've always learned it.

 

[mike wightman]

Hmm, and none of the standard designs have been shown to be wrong before now...

As Dan says, T20 is supposed to be based on High Guard.

If the designers have chosen to make armour so much cheaper then there is another difference between HG and T20.

Even offical ship designers don't always understand the rules - just look at the "HG armour value 0 costs tonnage" discussion

 

[Gruffty]

High Guard:

% of hull dTons required (at TL 13):

2% + 2%*required armor factor = dTons of armor.

For my 50,000 dTon ship [example armor factor of, oooh, let's say, 6] this is:

2% of 50,000 = 1,000 dTons
+
2% of 50,000 = 1,000 dTons * 6 = 6,000 dTons
=
1,000 dTons + 6,000 dTons
=
7,000 dTons for an armor factor of 6.

Cost:

dTons of armor *(MCr 0.3 + (MCr 0.1 * armor factor))
=
7,000 dTons * (MCr 0.3 + (MCr 0.1 * 6))
=
7,000 dTons * (MCr 0.3 + (MCr 0.6))
=
7,000 dTons * MCr 0.9
=
MCr 6,300 for 7,000 dTons of armor factor 6.

Or calculated the other way:

7,000 dTons * ((MCr 0.3 + MCr 0.1)*6)
=
7,0000 dTons * MCr 0.4 * 6
=
7,000 dTons * MCr 2.4
=
MCr 16,800 for 7,000 dTons of armor factor 6.

 

[archhealer]

Ok. Damnit. Now I need to go get my book and contribute to this discussion> i've designed dozens of ships and never been even slightly confused. Now I find I should have been? Crud. Crudpuckies on a stick.

 

[Gruffty]

T20 ship Armor Cost Example

T20, page 268: For example a TL 12, 200-ton ship with an Armor USP rating of 1 must have installed 8 units of armor.

Armor Units required, Tonnage & Cost
Armor Factoring: For a 200-ton ship = 2.
Tonnage: TL 12 armor = 2 tons per armor unit.
Cost: MCr 0.3 + MCr 0.2 per armor unit installed.

To achieve Armor USP of 1 (first layer of armor):
Armor Units Required: 2 armor factorings * 2 armor factorings = 4 armor units required.
Tonnage: 4 armor units * 2 tons of mass per armor unit = 8 tons. *8 tons is the tonnage space used in the hull of 4 *units* of armor.*
Cost: MCr 0.3 + MCr 0.2 per armor unit installed.

Thus:

4 armor units requiring 8 tons of space in the hull = Armor USP of 1 for a 200-ton ship.

Let's do the costings

.

Version A:
MCr 0.3 + (MCr 0.2 * number of armor units installed)
=
MCr 0.3 + (MCr 0.2 * 4 armor units)
=
MCr 0.3 + (MCr 0.8)
=
MCr 1.1 for 4 armor units requiring 8 tons of space in the hull = Armor USP of 1 for a 200-ton ship.

Version B:
MCr 0.3 + MCr 0.2 * number of armor units installed
=
MCr 0.5 * 4 armor units
=
MCr 2 for 4 armor units requiring 8 tons of space in the hull = Armor USP of 1 for a 200-ton ship.

If you work the cost calculations out based on the tonnage of the armor units, i.e. 8 tons of armor units you get:

Version C:
MCr 0.3 + (MCr 0.2 * tons of armor units installed)
=
MCr 0.3 + (MCr 0.2 * 8 tons of armor units)
=
MCr 0.3 + (MCr 1.6)
=
MCr 1.9 for 8 tons of armor units = Armor USP of 1 for a 200-ton ship.

Version D:
MCr 0.3 + MCr 0.2 * tons of armor units installed
=
MCr 0.5 * 8 tons of armor units
=
MCr 4 for 8 tons of armor units = Armor USP of 1 for a 200-ton ship.

I'm sure the problem I've been experiencing is from the use of the word "units" near the end of the sentence in the example. I'm certain the sentence should read something like this:

For example a TL 12, 200-ton ship with an Armor USP rating of 1 must have installed 4 units of armor (requiring 8 tons of space in the hull) and costs MCr <insert figure calculated using your preferred method!>.

Right - that's my problem sorted! I'm now certain there's a bug in the example in the book, I know how to work out the armor for my ship and I'm going to use the cheaper armor costing calculation .

It would be nice (although not essential) if we could get definitive answers from Hunter or MJD on the issues we've highlighted here.

BTW, I'm not critising T20 here - it's a big book with lots of stuff in it and a helluva lotta work went into putting it together. I'm pleased I bought it

; I just want to make sure my ship stats are OK.

 

[Commander Drax]

Oh Darn!, all of those designs I've just sold to the Imperium are flawed....

My head hurts, but I've checked Grufty's calculations and he does it the same way as me, so it must be right

I've never had a problem doing it that way.

When first starting designing ships using the T20 rules I found the explanations regarding armour as confusing, so I reverse engineered the standard designs, comparing them against the known facts available in the rules. Using Grufty's formula they all come out right..

What we need is an advanced ship design sequence that maintains the general simplicity of the T20 sequences for ease of use, but the flexibility of other products. I find the ship design rules to be far too limiting for my tastes.

 

[RainOfSteel]

Originally posted by Sigg Oddra:
I agree with Dan.

And I also find the original High Guard formulae easier to use than the T20 "simplification"

As do I.

When I find a T20 design sequence element that is precisely equal to HG2, I use the HG2 mechanic instead.

 

[Gruffty]

Originally posted by Commander Drax:
My head hurts, but I've checked Grufty's calculations and he does it the same way as me, so it must be right

Errrmmm.....which way is that, exactly? Cos I've forgetten which one is the *correct* way