Okay, so recently I've been working, Battlefleet Gothic rulebook in one hand, Rogue Trader in the other, to try and turn the warships of BFG into hulls and component configurations for Rogue Trader. I know others have done this, but I wanted to take my own crack at it and see how it works out. I was interested in the idea that really, a Lunar class hull should be able to represent all the different Imperial cruisers, since their only real difference (save for an extra turret on the Dictator) is the weapons loadout.

Previously, a lot of this was working out really well. For example, if you give the Lunar class two Mars pattern macrocannon broadsides, one on Port and one on Starboard, and then a Sunsear laser battery on each side, it works out exactly like a Tyrant class. In BFG, the Tyrant has batteries of Strength 6 at 30cm, compare this to Strength 6 at Range 6 in BFG, and Strength 4 at 45cm, compared to Strength 4 at Range 9 in Rogue Trader. Perfect!

It works for the Dominator class too. Two Mars pattern macrocannon broadsides, giving Strength 12 at Range 6 (or 30cm in BFG.) This would also work for the Gothic class, except the Gothic class will probably need either a special plasma drive or a special lance component, since the power requirements for the equivalent strength of lances is too high.

BUT, here's the problem. It occured to me that while this works out well for cruisers, when you compare it to escorts it all breaks down. The Sword-class frigate, for example, has a Strength 4 dorsal weapons battery in BFG. In Rogue Trader, the Sword class has two dorsal mounts, and is described, as it is in BFG, to have laser based batteries. But if you give the Sword two Sunsear laser batteries, as you would only naturally do, it ends up giving the Rogue Trader Sword an effective Strength of 8, at a BFG equivalent of 45cm instead of 30cm.

****, I was so close!

I realize this is really kind of pedantic, but I'd like BFG and Rogue Trader to have at least some symmetry, especially since the cruisers had been worked out so well. But think about it, since a Sword-class frigate's dorsal mounts can both fire port OR starboard, that means that a Sword class frigate's 2 mounts could theoretically do as much damage as the broadside of a Lunar class hull if that Lunar class were armed with two Sunsear laser batteries on one side. THAT can't be right.

You make a pretty good analysis of the offensive capabilities. I think the RT - BFG comparison falls apart even faster when you compare the defensive capabilities. In RT, the Sword has an armor of 18 and 35 hull; the Lunar an armor of 20 and 70 hull.

In BFG, the Sword has one shield and one hit point with a 5+ armor save (so two hits usually destroys it). A Lunar class cruiser has two shields and eight hit points with a 5+ armor save from the sides / rear and a 6+ save from the prow. Much more difficult to destroy the cruiser. By their point system, a Lunar is worth about 5 Swords. A pretty close estimate.

I think the Lunar is way too small in RT. If they wanted a larger ship, they should have just made another class or two or three, rather than try to make the cruiser work. But that is just my opinion. You could just as easily claim the cruiser class was ridiculously oversized in BFG - and don't even mention the battleships!

I don't plan to use BFG other than as a source of ideas for ship classes / concepts and names - except for some converted rules for fighters / bombers / torpedoes I have been toying with.

A couple people have tried direct conversions from BFG, and it by and large doesn't work well. The trick is to take another ship of the same class and compare the two. You'll have to rule of thumb it a bit, though, and most cruisers will end up with broadly similar stats unless you use some special rules to make them unique.

Shameless plug: www.darkreign40k.com/ships-of-the-void/ancient-vessels-and-equipment-of-the-expanse-26.html

I'm not sure I follow, how do you mean compare ships of the same class? Do you mean ships of the same classification, like cruisers and frigates and raiders?

AkumaKorgar said:

Yes, sorry about that mistype. Yes, you just compare the various types of raider, frigates, cruisers, (I used cruisers as a point of reference to heavy cruisers and grand cruisers, but battleships are right out.)

I feel that the inclusion of the cruisers, and perhaps even the light cruisers, was a mistake. In order to make them fit they had to be toned down, and the weapons on the escorts kicked up several notches. The rules as written, a pair of wolfpack raders stand an even chance against a cruiser. I am a longtime BFG player. No... Just no.

No game I run will include anything larger than a frigate except as a plot device. Why? Because there are some things bigger than a Rogue Trader, and the Imperial Navy is one of them.

Dabat said:

Pardon my language but how in the warp did you get a pair of Wolfraiders even close to a Cruiser in power?

a Cruiser can be equipped with shilds that can absorb 2 hits from every ship fireing at it plus an armour rating of 20 as well as 2 weapons on each side plus a prow mount. they can easyly turn anything below light cruiser weight into stellar dust without breaking a sweat.

I build a Cruiser with 10 SP in addition to the Hull cost that were geared towards combat but not armed or armoured as well as it could be at all to test it.

Hull: Cruiser
Class : Lunar
Speed : 5
Manoeuvrability: +13
Detection: +10
Hull Integrity: 70
Armour: 21
Turret Rating: 2
Space: 75 (62 used)
Power: 75 (70 used)
SP: 10 (10 used)
Crew: 100%
Moral: 100%
Weapon Capacity: Prow 1, Starboard 2, Port 2
Essential Components
Plasma Drive : Jovian Pattern Class 4 Drive
Warp Drive: Warp Engine
Gellar Field: Gellar Field
Void Shields: Multiple Shield Array
Bridge: Ship Master's Bridge
Life Sustainers: Vitae Pattern
Crew Quarters: Voidsmen Crew-Quarters
Augur Arrays : Mark-20 I.b Augur Array
Supplemental Components
Weapon Components: 1 Starboard Mars Pattern Macrocannon Broadsides, 1 Port Mars Pattern Macrocannon Broadsides, 1 Starboard Sunsear Laser Battery, 1 port Sunsear Laser Battery, 1 Prow Titanforge Lance Weapon
Cargo Holds & Passenger Compartments: -
Augments & Enhancements: Armour-Plating, Augmented Retro-Thrusters
Additional Facilities: -

I set it up against five Wolfpack raiders and it took them down while they barly scratched it. (both sides rolled about average, the Cruiser a little better).

I have played BFG a good deal and do not think that Cruisers in RT are nerfed in comparison to their BFG counterparts. But agreed it can be hard to translate them over, but so can normal enemies from the table top 40k game into DH and RT.

Also, remember that BFG isn't going to be 100% accurate/the truth, because it's nature as a balanced tabletop wargame means that it has to be done in the manner it is. A roleplay game, on the other hand, which doesn't need to be balanced, can be closer to the accurate abilities of the ships.

Just because a wolfpack couldn't take a cruiser in BFG (and they could, if they were lucky), doesn't mean they shouldn't be able to in the RP. Hell, it was a well used tactic during the Age of Sail, which 40k space navies/tactics/etc are based on, so I don't see why they shouldn't be able to have a small fighting chance.

... I can say my party not only mopped the floor with two wolfpack raiders, they successfully captured both, with a Dauntless...

delete post. accedental double posting.

Reply to everyone: Yeah, I don't know what the hell I was thinking when I typed that up. I said Wolfpack Raiders, I meant Sword Frigates. And I straight up posted the words 'stand an even chance' and left out the incredibly important caveat of my train of thought, I failed to include the important words 'of chaseing it away' IE: Too damaged to continue it's mission if it encounters any other resistance, thus forcing it to withdraw. That one sentence was bad even by my usual typo-ridden standards. ><

I have been an avid BFG player and am just getting started with RT, but my analasys is that Cruisers in Rt are stripped down military vessels that have been retrofitted for other purposes. I imagine even i fyou buy every possible military upgrade for a Cruiser it would likely fall short of the purly military cuisers of the Navy. I admit this is mostly a way to justify the descripancy between the two games, But escort class ships (most RT ships fit here) are really easy to kill in BFG, it would be interesting to send three or four frigates against a fully tricked out cruiser and see if it dominates them in RT, the way it owuld in BFG.

Short answer: No, the Cruiser likely wouldn't stand a chance. The frigates are faster and more maneuverable meaning the cruiser will have a hard time being able to bring the full weight of it's weapons to bear against them. In addition every one of those frigates has a frontal firepower nearly equal to the broadside of the cruiser. If I remember the math I worked out for this very situation correctly the frigates end up doing an average of something like 4-12 points a turn to the cruiser, each, with each of them having about a 1 in 5 of causing a critical (coming out to almost one critical a turn). While the cruiser in return does something in the area of 18-30 points back and has about a 1 in 4 chance of causing a critical. The dual reasons for the escort's ability to maul a cruiser are A: The cruiser has so few structure points compared to the smaller ships. And B: The escourt ships are able to mount capitol class weapons on their hulls and are thus are each able to bring the same amount of firepower (or nearly as much) to bear against a capitol ship as a capitol ship can bring back at them.

Please note, I am not knocking the overall ship system or the game itself. I think the idea behind the game is fantastic. My feelings behind the game are as follows: "I am richer than Bill Gates and the King of Saudi Arabia's love child, I get to sail the uncharted seas- erm,- Stars, plundering as I go with a whole army at my command... Plus I could encounter Tyranids!? Hell yeah! Let me get my dice." I Just don't feel that capitol ships fit well into the system as written.

Frankly, Rogue Trader, as written, is one of the best games I've ever played. I'm absolutely hooked, because of it's combination of the 40K universe with extraordinary freedom of movement for the PCs, along with the naval roleplaying aspect I've always been interested in. The capital ship thing bothers me but really, it's the only problem I have with the game.

I actually think I already worked out a solution, I've redone many of the weapon systems, so that now ships of frigate size and smaller can only take weaker batteries, which follows BFG firepower values a little more closely. This is a good alternative I think to simply making cruisers larger, which would require even more house rules.

I have to note that in these house rules I've come up with, the weakest guns are still stronger than the weakest guns in BFG, ratio wise, and of course escorts still will last longer than BFG implies, but I can live with this since most ships in the game are probably going to be frigates or smaller, and nobody wants to have a ship that blows up after a single volley.

The Sword seems a little odd in comparison to the lunar.

It's 1.6 km long vs the lunar's 5km. Volume cubes as size increases so it seems strange that a lunar which is ~3x the length of a sword only has twice the hull points.

If a sword is 1,600metres x 500 metres x 500 metres it has a total volume of 400,000,000 square metres, or 4 hundrfed thousand square kms.

If a lunar is 5,000metres x 1000 metres x 1000 metres it has a total volume of 5,000,000,000 square metres, or 5 million square kms.

The difference is 12x the volume but the hull points only double. Now obviously you can't draw a direct comparison to hull points from sheer volume, but there will be a relationship.

If we look at the age of sail and early powered ship design we see that the larger a ship was the larger its guns were. One of the definitions of a Battleship was a ship that had armour to protect against battleship cannon from a certain distance and cannon that could penetrate battleship armour within a certain distance. The Battlecruiser carried the same armament as a battleship but traded in the armour for higher speed and manoeuvrability.

Anyway, I say this because the simple fact is that a Sword would not carry individual weapons as powerful as those used by a lunar. One could argue that the stats given for weapons in the book represent an abstraction of sorts where the actual armament on the ship is represented that way, but I don't find it as fun. There is also the fact that the book mainly consists of escort vessels any way.

What you can do however, is grade weapons based on size. You could take the weapons in the book as the current 'size' weapons for escorts and scale up for things that are larger.

Historically ship sizes went as follows iirc:

Corvette

Frigate

Destroyer

Light Cruiser

Heavy Cruiser

Battlecruiser

Battleship

Now BFG doesn't always follow this. It places frigates as larger than destroyers (the cobra destroyer vs the sword frigate). But's a generally good guideline. Note that the term cruiser applied to a group of ships, there was no actual 'cruiser', just light and heavy cruisers

Anyway the point is that each hull type would mount weapons of varying sizes but limited by the size of the ship. For example a heavy cruiser might mount 8" guns and a battlecruiser up to 16" guns.

So what you can do is increase the range and damage of each weapon system depending on the size of the ship mounting it. I suggest something like:

+1Dam - light cruiser (dauntless)

+2Dam - Cruiser (lunar)

+3Dam - Heavy cruiser/battlecruiser

+4Dam - Battleship

With appropriate increases in range.

This leaves all the weapons in the book as 'escort sized' weapons, whilst still representing the cruisers et al as they should, massive behmoths that fire such large weapons they can obliterate smaller ships very quickly.

Hellebore

Hellebore said:

The trends in firepower from ships of different sizes tend to be slightly different in BFG - larger ships tend to carry a greater quantity of guns, capable of operating at longer ranges (all three classes of Imperial Navy Battlecruiser I know of differ from cruisers by having 50% greater range on their main guns, and the addition of a long-range lance battery on the dorsal spine; meanwhile, battleships tend to mount a dorsal weapon system, plus three distinct weapon components on each flank, plus an oversized weapon component in the prow, compared to the two on each flank plus prow torpedoes standard for a line cruiser), rather than necessarily having more powerful guns.

Personally, I think that halving the Strength of the Sunsear battery brings it into line with the firepower the Sword has in BFG (it takes two Sunsears, it can put out 4 shots maximum, equating to the FP4 battery the Sword has in BFG, and allowing easier conversion into a Firestorm by removing one Sunsear and replacing it with a lance). Maybe providing similar 'downsized' (ie, reduced Strength) versions of weapon components for frigates and raiders, while disallowing them access to larger weapon systems. I'd be inclined to either boost the hull points of cruisers or those of smaller craft (or both) to help cover the discrepancy to an extent as well.

Sure, but the actual weapons being represented are still fairly abstract. Take the models of the Hellebore and the Eclipse. The weapons actually modelled onto their hulls represent WB and Pulsar, but do so with multiple actual weapons - far more than the strength of the weapons depicted. Then you've also got the art of imperial battleships festooned with guns, far more than can be seen on the model. So it's safe to say that BFG's rules are very abstract in terms of representing the ship's actual weapon capacity.

It seems very odd that the larger ships wouldn't mount comparatively larger guns. Classic age of sail ships not only mounted larger ones but they could mount more because of the extra space afforded by the ship's size (re cubed volume). One way to look at it is that the stats given on an Emperor class Battleship are more closely a 1:1 representation of their actual loadout, with everything below becoming more and more abstract.

You could instead modify the amount of Strength each weapon has, rather than the damage. Or give them actual penetration rules. It seems rather odd that the game uses penetration in all other aspects, but when it comes to ships with phenomenal armour values there is no penetration. Penetration values would also aid in causing damage in the first place. They would also represent the increased power of a battleship's shot in comparison to smaller ships. All navies, current and historical, use different sized guns on their ships, mainly limited to ship size. If you mount a 16" gun on a frigate you could potentially tear the turret off, whilst the bulk of a battlecruiser can absord the force.

It could be a size table, rather than a modifier.

Size 1 - corvettes (all craft smaller than a destroyer)

Size 2 - frigates/destroyers

Size 3 - light cruisers

Size 4 - cruisers

Size 5 - battlecruiser/heavy cruisers

Size 6 - Grand Cruisers

Size 7 - Battleships+

For every point of size difference you receive +1 penetration on the damage roll. So a battleship shooting a a frigate would get 5pen against their armour.

EDIT: It also depends on how radical you want to get with any modifications to the actual rules. If you used the size rules from the normal game then smaller ships would be harder to hit/detect (as they should be). On the other hand having a -30 for that is extreme if it's on a ship that's only half the damage of a cruiser. So you'd probably have to go for a modification of the hull points for each type of ship as well.

Something like:

Size 1 - corvettes (all craft smaller than a destroyer) - HP 10

Size 2 - frigates/destroyers - HP 20

Size 3 - light cruisers - HP 40

Size 4 - cruisers - HP 80

Size 5 - battlecruiser/heavy cruisers - HP 160

Size 6 - Grand Cruisers - HP 320

Size 7 - Battleships+ - HP 640

Adjusted up or down depending on preference. I'd set the cruiser at ~100 HPs as a baseline. The above is a simply exponential increase, which does make some sense, although it might get a bit murky towards the end depending on the size differences between GCs and Battleships/cruisers.

Hellebore