To bring people up to speed on the Invincible, these are the two proposed profiles:
Admiral's:
Battleship 10 Shields 3 Speed25 Turns 45 Armour 6+/5+ Turrets 4
Prow 6 Torps
Dorsal 4 Lances@60cm L/F/R
P/SB Weapons Batteries FP12@60cm
Special Rules: May not come to new heading, rolls 2D6 per hit to check for Crits.
Mine:
Battleship 12 Shields 2 Speed25 Turns 45 Armour 6+/5+ Turrets 3 or 4.
Prow 6 Torps
Dorsal 3 Lances @60cm L/F/R
P/SB Weapons Batteries FP15@60cm.
Special Rules: May not CTNH, suffers Critical Hits on a 5+ and a +1 modifier on the critical hits chart.
Basically, the original profile of the Invincible (You can find it in the additional ships compendium), was meant to be a True Battlecruiser, but they screwed up a bit and only made a fast-cruiser with unfixed Retribution level firepower.
Admiral's Profile would work fine if we were going for a Light Battleship, but that's not what we're going for.
So how have I arrived at my version profile for a true battlecruiser? In the following, I'll go through the design process and a comparison with Admiral's:
Hits:
True Battlecruisers are as big as Battleships, with the same crew complement. They'll do you the same damage if they ram you or board you, and they'll have comparable damage control capabilities. These things all demand 12 Hits.
As for Xenos battleships having 10 hits, as Sigoroth said there's actually a pretty good case to be made for them having 12 hits. But even so, these are different hulls and so you can get away with different hits. Invincible uses the exact same hull as Retribution. There's no getting around the fact that every capital ship based on that hull has 12 hits, and there's no reason to set a precedent.
Admiral raised the idea of a supertanker that displaces the same as the battleship Yammato. I wouldn't give that 12 hits would I? Well actually I would. It's got the same mass, and it will do you the same damage if it hits you. It would definitely lose those hits much faster, and I'd probably give it AV1+ or Av2+ combined with special rules that halve its damage rolls and boarding value.
At this point I have to eat humble pie and admit I screwed up my math for my earlier toughness analysis. Nevertheless, here's how they compare against each other:
Retribution: 12 hits + 4 shields - (1/6*11) critical hits * 0.49 hits per critical = 15.1 hits 1-turn endurance.
Admiral's: 10 hits + 3 shields - (1/3*9) critical hits*0.49 hits per critical = 11.5 hits 1-turn endurance.
RC's: 12 hits + 2 shields - (1/3*11) critical hits*0.75 hits per critical = 11.14 hits 1-turn endurance.
Both are significantly weaker than a Retribution, though there's less than half a hit in it. But if you're taking that much firepwoer in one turn, you'll likely be braced, in which case mine has an additional 2 hits it can save against, gains an extra hit in comparison to Admiral's and so wins by more than half a hit. Mine is also stronger against things that ignore shields, like torps, AC, ramming and boarding. Admiral's is much stronger in a battle of attrition - 2 gothics will kill mine in about 5 turns. 2 Gothics would kill Admiral's in about 9. Admiral's is a good Light Battleship. Mine's a better Battlecruiser.
Weapons:
The purpose of True Battlecruisers also mean they are armed similiarly to Battleships - that's the whole point of them - strong enough to outgun anything smaller than them, fast enough to outrun anything tougher. Admiral has been his usual conservative self and recycled the original profile's weapons - but here's the thing. A profile can't have S4 Dorsals. It just can't. The maximum dorsal hardpoint is S3 Lances. As for Hardpoint bleed-over, I seem to recall a certain someone being particularly inflexible about allowing the Defiant the same thing, so I'm not letting that argument fly unless we're willing to re-open the Defiant's armament.
With S3 Dorsals, Admiral's Profile outguns an Armageddon by less than one lance - not by enough that the Armageddon wouldn't fancy having a go. FP12 is just too low.
So my profile proposes FP15@60cm and 3 Dorsal lances. This is actually less broadside firepower@60cm than Admiral's 4L and 12WB proposal, so that can't be the objection. The objection seems to be that it's somehow stronger than a Retribution's FP18@45cm. I think this is rubbish - the Retribution's FP18 can expect to score an additional hit in 3/4 of cases, and the extra 15cm of range isn't so impressive as to more than make up for that - expecting just one hit against capital ships abeam at long range. The two are equivalent. The reason mine doesn't have FP18 is that as a battlecruiser Invincible is going to be far less at home in the centre of an enemy fleet - the range is important.
Another possible objection is that IN WB hardpoints go 6@30, 5@45, 4@60 - this is nowhere near universal, with the Mars, Armageddon, Emperor, Oberon and Fixed Retribution all providing counter examples, so that's not a strong objection either. FP5@60cm per hardpoint is perfectly acceptable.
The final objection is that it goes after the Retribution's role - this really won't be the case, because the Retribution is a Linebreaker and the Invincible is stand-off. This is slightly down to the weapons having less strength/more range, but mainly down to the Invincible just not being able to hold its own in the centre of a hostile fleet. The Retribution is better for leading a charge of line breakers, whilst the Invincible is better in a harrassing role.
Other:
So it's 12 hits, and has the firepower of a proper battleship and not just a light one. What can be done to make it into a True Battlecruiser? Speed 25, obviously. The game's Armour doesn't have fine enough grades to distinguish the armour of a battleship from the armour of a cruiser, so the armour of a battlecruiser isn't going to be distinguished either, it's still going to be 6+/5+.
But we still have to make it more fragile to be a battlecruiser - this means fewer shields, possibly fewer turrets, and some special rules. I think 2 shields captures the feel of a battlecruiser better - with 12 hits, 3 shields is nearly a battleship.
Both Admiral and I have adopted 1/3 of hits cause criticals (though my 5+ is much neater than his 2D6), whilst I've got an additional +1 modifier on the Critical Chart. Admiral calls this excessive punishment (though without it my version has significantly stronger 1-turn endurance than his), whilst I call it fluffy for a Battlecruiser to be extremely vulnerable to mishaps.
And there you have it.
