MGT Only: Battle tender design

[Brandon C]

I'm running into a bit of a quandry on a design for a MgT/HG 1e battle tender for 300 ton gunboats for a possible pockwt empires campaign.

I want the tender to carry six gunboats. Haviing the tender use a dispersed structure and attaching the gunboats with docking clamps seems a reasonable approach -- but not for MgT.

The tender comes in under 2,000 tons unloaded but almost 4,000 tons with the gunboats attached (1,00 ton tender, 1,800 tons of gunboats). I have two at least choices:

(1) calculate the displacement and cost of the drives as if it were a capital ship but use the rules in the core book for everything else.

(2) use only the core book, selecting drives that give double the performance I want the loaded tender to have (Jump 3, 2G, btw).

Both have advantages and disadvantages.

 

[robject]

Go for option 1. The result will be a valid design. The core rulebook made a grave error by not having a drive potential table compatible with anything AND not able to be clearly extended.

 

[McPerth]

Let me begin answering your last part, as I guess it would be easier for me to explain myself:

As for performance, I'd suggest you to calculate your needs with the loaded ship (with its full gunboats complement), and just calculate what result does that give on it when unloaded (and maybe when loaded, but not fully so).

If so, as MgT 1E: CB only reaches up to 2000 dtons, you'll need HG rules.

See that if you begin by designing a 2000 dton ship using CB rules, you'll probably need anyway some details from HG (e.g. drives, as you'll sure need those in HG pg 73, docking clamps, etc...), they you'll have problems to calculate them in HG rules when fully loaded (and so 4000 dtons), as the systems are not fully compatible.

To show you this, to give your 2000 (unladed) dtons J6/M4 capacity by using CB rules (and HG page 43 drives), you'll need DD JD and PP and U MD, with an added volume of 299 dton (195 for JD, 97 for PP and 37 for MD) and a cost of MCr 650 (320 for JD and 254, PP and 76 for MD). If you use HG, you'll need 13.75% of your ship (7% for JD, 5% for PP, assuming no TL modification, and 1.75 for MD), for a total of 275 dton and at a cost of MCr 280 for JD (MCr 2/dton for 140 dtons), MCr 250 (Mcr 2.5/dton for 100 dtons) for your PP and 17.5 (MCr 0.5/dton for 35 dtons) for the MD, for a total cost of MCr 547.5. So, by using HG rules you need 24 dton less and its cost is MCr 102.5 cheaper.

As an aside, I cannot find the fuel needs for a DD rated PP in HG...

By extrapolating it from the 2 dton/rating shown in CB page 107. it would be 56 dton per 2 weeks, while in HG the fuel needs would be 67 dtons (2/3 of PP volumen) per two weeks, so partially forfeiting the volumen gains (and even being negative if you want more endurance).

Those same HG numbers will give you rating 3 for JD and PP and rating 2 for your MD, that was what you told you're looking for. No provision for those drives to be used in a 4000 dton ship in CB rules...

 

[AnotherDilbert]

As McPerth says, CB does not allow what you want. Make the tender 2001 dT and use the capital ship rules. Problem solved?

 

[McPerth]

As McPerth says, CB does not allow what you want. Make the tender 2001 dT and use the capital ship rules. Problem solved?

I don't believe the extra ton is needed. I guess you can design smaller ships using capital ship rules if you want, even if they are not fully compatible with the CB system.

Same happened with CT:LBB2 and CT:HG...

 

[Brandon C]

Yeah, CT had the breakpoint at 5,000 tons, MgT has it at 2,000 tons.

For powerplant fuel, 0.01*Displacement*Pn per two weeks seems to work out reasonably well.

Later today, I may explore a third option: run a linear regression on the CB drive costs and volumes to see if I can get workable formulas.

 

[robject]

Later today, I may explore a third option: run a linear regression on the CB drive costs and volumes to see if I can get workable formulas.

It's broken in a nonlinear fashion: there's a jump after drive F, then another jump or two later.

I had forgotten about that during its writing. I vaguely recall saying something foolish like "just cut out the middle bits". After the book came out, I had simply assumed it was a regularized Book 2 DPT. I was dismayed to find that wasn't true.

So here's what you need to do: derive the formulas according to A-F, and let it ride all the way past the end of the DPT. Then note the places where the numbers align, and attach the MgT CB drive letters to *them*, but note that the gaps represent valid drives as well. Figure out a naming system that accommodates them.



OR, for sanity's sake, derive the formulas according to A-F, let those formulas generate the table as high as you need them to go, then letter THOSE drives, ignoring the CB's nomenclature as a regional mapping by a COTS distributor.

 

[Brandon C]

It's broken in a nonlinear fashion: there's a jump after drive F, then another jump or two later.

So here's what you need to do: derive the formulas according to A-F, and let it ride all the way past the end of the DPT. Then note the places where the numbers align, and attach the MgT CB drive letters to *them*, but note that the gaps represent valid drives as well. Figure out a naming system that accommodates them.

OR, for sanity's sake, derive the formulas according to A-F, let those formulas generate the table as high as you need them to go, then letter THOSE drives, ignoring the CB's nomenclature as a regional mapping by a COTS distributor.

Yes, I chose A-F since it seems like a 200 ton hull was the perfect ship size

The formulas I came up with are pretty good in this range bu become very different as hu;ll size increases (as you say).

FWIW, here are the formulas I came up with:

Jump drive: Hull x Jn x 0.025 + 5 tons, Hull x Jn x 0.05 MCr
Maneuver drive: Hull x Mn x 0.0075 + 1 tons, Hull x Mn x 0.02 MCr
Power plant: Hull x Pn x 0.015 + 1 tons, Hull x Pn x 0.04 MCr

 

[robject]

Maneuver drive is probably best calculated using drives B-F, because I had Gareth require a minimum volume of 2 tons, which overrides the formula at Drive A. If I recall, the formula might be

1%Mn - 1 tons

E.G. 2G in a 100t scout is

1% x 100t x 2G - 1 = 2 - 1 = 1, but min vol is 2, so 2 tons.

E.G. 2G in a 200t trader is

1% x 200t x 2G - 1 = 4 - 1 = 3 tons.


It does disadvantage larger ships compared to the CB drive letters, but it's a sane formula, it doesn't cramp anyone's style, and it's more closely aligned with CT Book 2, Traveller5, and MgT2.0.

 

[AnotherDilbert]

I don't believe the extra ton is needed. I guess you can design smaller ships using capital ship rules if you want, even if they are not fully compatible with the CB system.

I'm perhaps too literal minded, but I went with:

Capital ships range between 2,001 and 1,000,000 tons

MgT1 HG, p62.

 

[AnotherDilbert]

As an aside, I cannot find the fuel needs for a DD rated PP in HG...

High Guard Errata, p1:

Add another column to the Extended Drive Ratings table, for Power Plant tons of fuel per 2 weeks;
AA = 52
BB = 56
CC = 60
DD = 64

 

[McPerth]

I'm perhaps too literal minded, but I went with:
MgT1 HG, p62.

Agreed, but nowehre (at least to my knowledge) is forbiden to desing smaller ships with Capital Ships Rules, as in CT you could design small ships by using HG rules, even if they are thought For ships over 5000 dtons

High Guard Errata, p1:

TY for the clarification. They are a little higher than what I extrapolated (8 dtons more per 2 weeks in this case), so lowereing the fuel gain for using them...

 

[Brandon C]

I designed three versions, using the three approaches for drives (and fuel) mentioned in the thread. One design needed a larger hull, but otherwise the ships were built to similar specifications: Jump 3 and 2G with six 300 ton gunboats in docking clamps, dispersed structure for ship.

Using the core book drives (extended in HG), the hull was 1,800 tons and cost was ~MCr 940.

Using the formulas for capital ship drives (treating the carrier as a 3,600 ton ship), the hull was 1,800 tons and cost was ~MCr 870.

Using the drive formulas in this thread, hull was 2,600 tons and cost was ~MCr 1,700.

Approaches 1 and 2, in the end, gave overall similar results. Approach 3 probably makes he concept unusable for the campaign (a jump shuttle for each gunboat is probably cheaper)

 

[Brandon C]

Oh, almost forgot...

Thanks to everyone who participated in this thread.