Point-Defence Laser Batteries in HG - Am I Holding This Right?

[MattL]

I'm not sure I understand the HG rules for PDLs - please, dear reader, give me your thoughts.

According to HG, p. 40:
"A point-defence laser battery consists of linked short-ranged laser turrets controlled by their own automated computer. This removes the need for separate gunners dedicated to point defence, needing only a command from the bridge to activate when an incoming attack is detected.

A point-defence battery automatically intercepts missile and torpedo salvoes just before they make their own attack rolls. A point-defence battery reduces
the number of missiles attacking a ship each turn by its Intercept score."

There's mention of DM penalties in the following point-defence gauss battery section, so that suggests it doesn't actually just automatically intercept stuff, rather there's a skill check to be made. It's automated, so I'd guess it uses the ship's Fire Control software, but it says it "turrets controlled by their own automated computer". Maybe it comes with the Virtual Gunner software package, but if so I've no clue the software score. If I ignore the "own automated computer" phrase and just use the ship's Fire Control software, does that count as one of the Fire Control software's automated attacks? I'm going to guess so.

Lastly, for its Intercept score it just says +2D for Type I, +4D for Type II, and +6D for Type III. I get the sense that I'm supposed to add, say, 2D to something, but I don't know what. Am I supposed to take the Effect of this automated Fire Control attack and add +2D (or whatever) to it and that's the number of missiles intercepted?

That's likely what I'm going to do here - use the ship's Fire Control automated attack and add the +2D (or whatever) and that's the number of missiles intercepted. That seems the most sensible interpretation to me, but I'm totally guessing here.

Is this how you interpret the rules as written?

P.S. This makes the Dragon system defence boat with its Type II Point Defence Laser an absolute missile soak. It can effectively just ignore an average of 14 missiles per round and any that get through do hardly anything against Armour 13 unless they're advanced or nukes. Add in electronic warfare and missiles are useless against it unless thrown in capital ship quantities. Seriously, you need a 100-ton medium missile bay and its salvoes of 24 missiles to even have a chance of harming this 400-ton boat.

 

[AnotherDilbert]

There's mention of DM penalties in the following point-defence gauss battery section, so that suggests it doesn't actually just automatically intercept stuff, rather there's a skill check to be made.

It's not a skill check, just a roll. There's no gunner, and no computer software, involved.
Each Type III battery destroys 6D missiles, only modified as per HG, p40.

Lastly, for its Intercept score it just says +2D for Type I, +4D for Type II, and +6D for Type III. I get the sense that I'm supposed to add, say, 2D to something, but I don't know what. Am I supposed to take the Effect of this automated Fire Control attack and add +2D (or whatever) to it and that's the number of missiles intercepted?

They add together with themselves. One type III destroys 6D missiles, two type IIIs destroys 12D missiles.
It's automatic, i.e. no gunner, no skill, no software, no check, no Effect.

Fire Control only applies to attacks, PD isn't an attack.


The point of PD batteries is that they destroy missiles from any number of salvoes, unlike a laser turret that can only destroy missiles from one single salvo.

If a fighter swarm launches 50 salvoes of one missile each, laser turrets and EW will not be effective, but a PD battery will be.

PD batteries are also effective at shorter ranges, where missiles attack immediately, not leaving time for EW and PD actions by the crew.

P.S. This makes the Dragon system defence boat with its Type II Point Defence Laser an absolute missile soak. It can effectively just ignore an average of 14 missiles per round and any that get through do hardly anything against Armour 13 unless they're advanced or nukes. Add in electronic warfare and missiles are useless against it unless thrown in capital ship quantities. Seriously, you need a 100-ton medium missile bay and its salvoes of 24 missiles to even have a chance of harming this 400-ton boat.

Quite, but squeeze a bit and it could easily carry two medium missile bays, launching 48 missiles.
Still between EW and PD, it would easily destroy that at range. But in large numbers they could bother larger ships.


Missiles are seriously nerfed in HG'24 compared to HG'22. Launch them in large numbers or not at all...

 

[Condottiere]

It costs more, and takes up more space.

Also, only takes out missiles; for torpedoes, you'd need actual turretted lasers, and gauss point defence.

 

[MattL]

Also, only takes out missiles; for torpedoes, you'd need actual turretted lasers, and gauss point defence.

This also confuses me. As I posted earlier, in HG'24 it says:

"A point-defence battery automatically intercepts missile and torpedo salvoes just before they make their own attack rolls. A point-defence battery reduces the number of missiles attacking a ship each turn by its Intercept score."

This appears to be in the context of PD Lasers, as literally no other context has been introduced at that point. Only later are gauss variants introduced, which then suggests that the above is may be a generalized capability of PD systems regardless of whether they are laser or gauss.

The whole section is poorly written. It should introduce PD weapons in general, then describe the difference between lasers and gauss variants. It doesn't do that. It instead launches into PDLs, then lists general capabilities of PD weapons (without mention there's anything other than PDLs), then PDLs again and finally brings up the fact there are gauss versions as being "also available".

Thank you for your help in understanding the author's intent.

 

[Sigtrygg]

Traveller canon has rapid pulse plasma/fusion guns used in point defence in ground warfare, vehicle, and air combat all the way back the LBB:4 Mercenary. There should really be a ship mounted variant. Hmm, JTAS potential...

 

[AnotherDilbert]

"A point-defence battery automatically intercepts missile and torpedo salvoes just before they make their own attack rolls. A point-defence battery reduces the number of missiles attacking a ship each turn by its Intercept score."

Of course they work against torpedoes as well as missiles, presumably at the normal 50% rate.

 

[rinku]

Traveller canon has rapid pulse plasma/fusion guns used in point defence in ground warfare, vehicle, and air combat all the way back the LBB:4 Mercenary. There should really be a ship mounted variant. Hmm, JTAS potential...

Point defence at ground combat ranges vs ground combat missiles doesn't automatically work in space.

I'm not totally discounting it, mind. But ton for ton and credit for credit, laser based solutions may simply be more effective in a vacuum, which could explain why we've not seen it before.

 

[AnotherDilbert]

Plasma and fusion worked perfectly well as PD in CT HG'80 and hence MT:
HG'80, p45:



HG'79 even allowed Particle Accelerators to PD:

HG'79, p48:
Missile attacks must pass through sand, laser, energy weapons, and particle accelerator fire, black globe fields, nuclear dampers, and repulsors before attempting hits against the target hull.

 

[Sigtrygg]

Point defence at ground combat ranges vs ground combat missiles doesn't automatically work in space.

I don't see why not, the space based point defence has more time to generate its targeting solution, and the ranges of point defence sensors in Striker, plus the ranges of the guns themselves, can comfortable achieve the PD role.

I'm not totally discounting it, mind. But ton for ton and credit for credit, laser based solutions may simply be more effective in a vacuum, which could explain why we've not seen it before.

More likely they just haven't looked back at it. Point defence rapid pulse plasma and fusion guns replace pulse lasers and gauss likely due to theri ridiculous rate of fire capability.

In the "real world" a bolt of plasma is likely more capable of killing a missile or torpedo that a similarly energetic laser system.

Need to go study up on this, both rules wise (Striker et al) and "theoretical" plasma weapons from sci fi (B5 springs to mind)

 

[Condottiere]

So should a bunch of steel ball bearings, bearing down on the missile salvo.

 

[rinku]

I was wondering how fast the plasma is going. Unlike photons it has to be projected.

A quick search suggests 10,000 km/s (about 3% of light speed) is likely, based on current research into high energy plasma railguns. So that's probably good enough, but if a laser can deliver the same punch at 30 times the speed and considerably further range, for less power, I can see why they would be favoured for dedicated point defense systems.

 

[rinku]

So should a bunch of steel ball bearings, bearing down on the missile salvo.

Spreading out and only impacting by sheer accident, you mean.

 

[rinku]

In regards to PD weapons vs torpedoes, PD effect is expressed in terms of missiles, but so are normal lasers in CRB. Torpedoes have a rule that any point defense halves its effect against them (p39); PD weapons appear to be basically all effect, so for a Type II PD laser battery vs a Torpedo salvo, roll 4D and halve the result.

Concerning a plasma version, given that the plasma bolt is intermediate between lasers and gauss in terms of velocity and is probably insta-killing on any hit the same as a gauss weapon, maybe halve the gauss PD penalty for high speed targets? Cost and power would be in line with plasma turret weapons vs beam laser ones (1.5x power, 5x cost), so you'd end up with something like:

Type I Plasma point defense: TL 10, +2D intercept, 15 power, 20 tons, MCr25; DM -1 vs Thrust 12-14, DM -3 vs thrust 15+

A little more effective than the gauss weapon ones vs high speed missiles and torpedos, but a little less so than the laser ones, while being more expensive and using more power. So, while a gauss one can be justified as being less effective against fast missiles and having ammo, but being cheaper with less power requirements, it's hard to see why a plasma (let alone a fusion) point defence system would be developed.

However, I'd support plasma and fusion turret use as emergency point defence. They're not there for that reason, but it seems fair they might be able to be used, especially against slower threats.

Or, maybe they are just not suitable? Laser Barbettes can't be used for point defence. Neither can railgun turrets. It's just laser turrets and specially designed 20 ton point defence weapons.

 

[Condottiere]

Spreading out and only impacting by sheer accident, you mean.

1. Place them in a canister.

2. Launch in general direction of salvo.

3. Wait for it.

4. Pro(xim)it (fuse).

 

[rinku]

Unlikely to get within even a hundred km of them, let alone 100 metres.