Weeeeell, you can call the Custodian a battleship if you want, just give it a rule allowing it to turn after just 10cm. I mean, a xenos race could have a corvette sized vessel as their battleship with their cruisers and escorts being no bigger than attack craft of other races. What a race calls a battleship and what the rules call a battleship are different things.
The thing that gets me is the size of the ships. They're smaller than their IN/Chaos/whatever counterparts. Hell, they're smaller than their own precursor ships. So their BB is 10 hits, rather than 12, their CA is 6 hits instead of 8 and their CL is 4 instead of 6. Why is this so? Well the answer to that is ... Forgeworld have no idea of scale. They made the models too small. So we can't justify giving them the regular amount of hit points. Fine. However, while we know what the REAL reason is for why they're smaller, that doesn't mean that we can't give a design oriented reason for it.
In other words, why did the Tau take the successful design of the Hero and then make it less durable? If Forgeworld had have made the model larger it would have been 8 hits, but since they didn't, why did the Tau make it smaller? Well, a reduced mass should be easier to turn. Tau philosophy of war is to try to outmanoeuvre their opponents. They have skimmer technology and try to remain mobile rather than holding ground. Sure, they're not as fast as any of the Eldar races, but they're pretty much on a par in terms of agility.
Of course, this is all on the ground stuff. You could make the argument that they're not as advanced in space. Well, that was true, and hence we got the SG Tau fleet out of it. Now however, we have had some sort of revolution in Tau technology. This must be the case since they've gone to all the trouble of making an entirely new fleet rather than just modifying their old one. Where their old ships were bulky and blocky, much like the alien ships they were copying, this new fleet is so advanced that the Tau are even able to input their own aesthetic into the design. If they have advanced so far as to produce ships that are quintessentially Tau then it stands to reason that these ships should be able to fulfil the Tau war doctrine too. Why bother making an entirely new kind of ship if you're just making it look nice?
Of course, some argue that it's just the new warp dive technology at play. However, that's still no reason to make their ships smaller. They have to be getting something back for doing this. It had to be by design. If we were talking about another race then it would be a no-brainer to say that since they're lighter they have greater agility. For some reason just because it's Tau we don't make that same connection?
The SG fleet was not a "Tau" fleet. It was a "new guy" fleet. That was fine. I liked the SG fleet for that reason. However we should not stop the FW fleet from becoming a "Tau" fleet on the basis of some nostalgia for the "new guy" feel. It's not as if we're going to get a new Tau fleet of models released any time in the next 10 years for us to fully give them all the rules they need to become a proper Tau fleet.
So the argument for greater agility rests on 3 things:
1) Tau doctrine of war.
2) Basic premise of mass/agility trade-off
3) Tau imperative for making smaller ships
The Tau want to be more agile. Making lighter ships should make them more agile, assuming technological capability. They did make their ships lighter, they did stamp their aesthetic on their ship designs, they did make an entire new fleet. This suggests they did have the technological capability.
As for balance, well, the Dark Eldar are as agile or even more so and much faster, are you saying they're overpowered? Surely it would be best just to give them the 90° turn and balance their guns accordingly. With predominantly forward-only facing firepower this added agility is not as deadly as it would be for the broadside armed races.
Okay everyone, you’re all going to want to sit down for this one. You ready?
Are you sure?
Okay, here goes.
For the most part, I agree with Sigoroth.

<gasp!>
That’s right, there, I said it. The reason why this response took so long is because first I broke out all the fluff and materials, then spent several conversations on the phone with Bob, then we pushed some models around, then I spoke with Bob some more, then we traded e-mails, then I once again pushed some models around. Here are the very valid points Sigoroth brought forward, including some points that have come up earlier (mainly form Horizon) that didn’t come up here:
1. He is right- the new Forgeworld ships are physically a lot smaller than the GW ships. The fluff for this is that the new ships were built from the Tau aesthetic instead of the clunky, modular older designs based on recovered technology. The larger problem is this- how do we interpret the size change in fluff? The largest combat experience they have is against the Orks, which is another prow-heavy fleet, which explains a lot about their design philosophy, and why they were so poorly prepared for the Imperials.
2. Making ships faster as at least as difficult as making them more maneuverable if not more so, and the biggest problem with this fleet is maneuverability so the smaller size of the fleet can actually be justified quite nicely by saying “Tau made them smaller so they could be more maneuverable.†Sigoroth brought forward an argument too valid to ignore. The whole point of the Forgeworld fleet is exactly the point he makes above- The Tau moved away from the clunky, modular ships they made (because it was all they knew how to fabricate at the time) to create starships more in keeping to the way they actually fight.
3. What Sigoroth doesn’t address here is Horizon’s biggest argument- the Custodian has too many launch bays. Ray is of the same mind, and I fought it tooth and nail because frankly, it was part of the Tau fleet’s design theme that they be ordnance-heavy, which I was trying to stick to. However, Their older fleet was ordnance-heavy because Mantas and Barracudas were the very first space-based weaponry they perfected, with Explorers being little more than their name suggested, giant trade and exploration carracks that were so poorly defended, the fast and dirty solution was to gut some the cargo bays to create Barracuda and Manta hangars. The Hero was an intermediate solution as the first purpose-designed warship, but it was with the Emissary that the new design philosophy was perfected. Though the Emissary itself was never designed to be a purpose-built warship, the technology perfected in its design later brought about the Castellan, Protector and then the Custodian.
4. This impacts the entire fleet in a way far greater than anyone addressed here, which only came about when I started building a test fleet to push models around. By making these changes, the more Kor’or’vesh ships you take, the more ordnance-poor and gun-rich the entire fleet becomes. This may not be themeful for the original GW fleet design, but it makes PERFECT sense if the Tau have evolved enough that they no longer need Mantas to defend their ships because they created a true fighting force in its own right, which is what the Kor’or’vesh is supposed to be.
5. So what? Well, the Tau’s biggest problem is how ordnance-reliant they are, and how overpowering the Kor’or’vesh ships made the fleet based on the original fleet list from Forgeworld. Following the guidance we have always been working under, our intent was merely to tweak the insanity that was the Forgeworld list to something more bearable. I for one have strongly resisted completely re-doing the Forgeworld fleet list because I believed it to be beyond our mandate, but the reality is this- the Forgeworld fleet list from Imperial Armor #4 was broken, and in any case it was never official anyway. As it was never official, there really is no reason why we can’t simply toss the whole thing in the bin and start from scratch.
6. We are not going to incorporate all the suggestions here. Once again, the goal is to make ALL the players happy, which means game balance and fairness against ALL fleets will always trump cool ideas and fluff-accuracy. However, here’s our solution set that I will work on this weekend:
- a. The internalized tracking systems for the Kor’or’vesh vessels was something new that we created to make up for crappy turning. We can get rid of this and say the Custodian has the Messenger-style external system. That gives the odd circular sensor array a function and a reason to really want this model. It is also a cheap and easy way to re-balance the Kor’or’vesh after we make other changes. For instance…
b. Protectors and Emissaries will turn 90deg and have deflectors, and they ONLY move 20cm. Tau are not better than Imperials: better turning means slower speed. They will also lose their internalized tracking systems, which was a gimmick we created specifically for this fleet and can get rid of if we are instead making these ships more maneuverable. Launch bays will be reduced to 1, and like before the Emissary carrier variant can only launch fighters.
c. For something as important as creating new rules, I take nobody’s word as gospel unless I playtest it myself. I pushed two of Horizon’s Distant Darkness ships around. With small tweaks, it will be one of the Protector variants. (Will somebody PLEASE restrain Horizon!!!) 
d. If Protector launch bays get dumbed down, they no longer need a fleet restriction of any kind because they are now self-limiting. (has Horizon been restrained yet? Really…)
e. To make up for what we take away, the firepower for some of these vessels will be slightly tweaked upward, and the prices remaining as-is. Caveats: 45cm ion cannons will be L/F/R only on the Custodian, prow-only on the Protector and no other ship gets them (it will be an exceedingly rare weapon in general). NO 60cm weapons whatsoever.
I should have all this ready by Monday night.
- Nate