How far do Ship sensors work to?

[Rel Fexive]

I suspect that is the most likely answer; the text says the stealth jumping ship is detectable on a roll "if it is within the ‘limited’ detail range of the sensors" but "within" could include the range for 'full' too, or exclude it as it doesn't specifically name the 'full' bands.

 

[Vormaerin]

It could mean that, but it would make stealth more effective than in other editions of Traveller that discuss jump flash. The real key to not being detected when arriving is to appear behind planet or other sufficiently large celestial objects.

Also, kind of moot because if a ship is within full sensor range, you are going to see it. The point of jump flashes at long range is that it tells you that the indeterminate blip is a ship that just arrived. You'll know that if it drops close to you without needing to detect the flash.

 

[Rel Fexive]

All good points.

 

[tytalan]

The description of the stealth jump mechanics is also from High Guard 2022 and it refers to the level of sensor detail required to detect a jump, stealthed or otherwise, not the range bands. So the addition of further range bands makes no difference, and the "sensor target" table from the core book posted above has not been supplanted by a different table in HG2022.

I hate to tell this but your wrong since if you actually read the part in HG2022 it stated the changes to the sensor table otherwise there is no such thing as stealth jump. You need to actually read both to understand this.

 

[Vormaerin]

The part in HG just says "The core rulebook gives the info for up to Distant". Then it says that detecting at Very Distant needs a 14+ Sensors roll and Far is limited to very rough size. The Stealth Jump says that its a 14+ at limited sensor effect and automatically fails if outside the minimum detail range. So is your position that "outside minimum detail range" means beyond Distant? Because "minimum detail range" is nowhere defined. Is Minimal and "Minimum detail range" the same thing? Nor does it actually say that Very Distant is beyond "minimal". Just that you need a 14+ sensor check instead of an 8+ sensor check to detect. What do you detect if you do make that 14+ roll? "minimal" information? something less than minimal? If so, what?

It says that a ship that emerges within minimum detail range is automatically detected. But it also says that you can detect Jump Flashes at Far distance, you just can't get much detail on the size of the ship.

One way to rationalize this is saying that out to Distant, jump flash is automatically detected, but it's only detected on a 14+ beyond that. While stealth jump means that the 14+ kicks in at Limited and also applies to Minimal. But the new sensor bands are automatically undetected.

Mind you, if you appear significantly inside the outer limit of "Distant" and the ship doesn't fail its regular sensor check, they are going to know you are a ship even without the jump flash. Of course, a civilian ship has a less than 50% chance of spotting a ship docked next to it since there doesn't appear to be a sensor range modifier table. So you need a 10+ to spot him and your average merchant probably has Sensor 0 or Sensor 1.

 

[CordwainerFish]

Of course, a civilian ship has a less than 50% chance of spotting a ship docked next to it

Helps if you take the lens cap off.

 

[Vormaerin]

Helps if you take the lens cap off.

You are asking an awful lot of those poor undercrewed merchants.

 

[CordwainerFish]

Knew I had this lying around:

 

[tytalan]

A lot of detecting other ships depends on the grade of sensors and the level of hull stealth. Even military grade is going to have a hard time detecting a ship with advance stealth hull, a DM of -10 will do that and that’s before you consider range. Even Advance sensors are running a -6 vs advance stealth.

 

[Vormaerin]

Obviously. You have a situation where the basic act of spotting another ship is overly difficult (the rules say it takes a Sensors roll without specifying a difficulty, so that defaults to 8+ before modifiers). And Stealth can give you negative modifiers that a ship has no effective way of countering that I have seen in the rules. If there are other modifiers out there, I'd love to know about them.

Though I don't know where you get -10. The rules say TL 14 stealth (Advanced) is -6. Which is still pretty overwhelming. The saving grace being it is ridiculously expensive.

 

[AnotherDilbert]

Though I don't know where you get -10. The rules say TL 14 stealth (Advanced) is -6. Which is still pretty overwhelming. The saving grace being it is ridiculously expensive.

Stacks with "Emissions Absorption Grid"? It did in HG'17.

 

[tytalan]

Obviously. You have a situation where the basic act of spotting another ship is overly difficult (the rules say it takes a Sensors roll without specifying a difficulty, so that defaults to 8+ before modifiers). And Stealth can give you negative modifiers that a ship has no effective way of countering that I have seen in the rules. If there are other modifiers out there, I'd love to know about them.

Though I don't know where you get -10. The rules say TL 14 stealth (Advanced) is -6. Which is still pretty overwhelming. The saving grace being it is ridiculously expensive.

View attachment 1515

The rule also says additional-1 for each different in tech level!
“
STEALTH
Stealth absorbs radar and lidar beams, and disguises heat emissions, applying a negative DM to Electronics (sensors) checks made to detect or lock onto the ship
(see the Stealth Types table). Apply an additional
DM-1 for every Tech Level the ship is higher than the sensors trying to locate it. At TL8, Stealth consists of an emissions absorption grid on the hull that nullifies electronic emissions. At TL10+, Stealth is achieved by applying a coating to the exterior of the ship and no additional tonnage is required. See the table below for the Tech Levels, cost per ton of hull, the DM applied to Electronics (sensors) checks when trying to detect the ship and tonnage required. Stealth cannot be combined with Reflec.”

 

[Sigtrygg]

What do they do with the energy they absorb?
Where do they hide the waste heat from the ship systems?

 

[Vormaerin]

@AnotherDilbert
No, it is included in the stealth systems in the Update, not a separate system.

@tytalan
Yeah, the TL is a modifier, but a 4 TL advantage is pretty massive. The expected value of a non military ship in the Imperium is TL 12. Most paramilitary ships are TL14+. There's probably some shipyards making TL9 or TL 10 ships, but that's a lot more likely outside the Imperium. Inside the Imperium, you'd have to have a really good reason to buy a ship that low tech. You aren't likely to get a -4 from the TL difference.

@Sigtrygg
Well, there is a +1 DRM if the power plant is on. +1 DRM per point of Thrust being used. So it isn't completely hiding the waste heat. But even a military ship (Sensors +0) is going to have a hard time spotting a full stealth ship. 14+ needed to spot the stealthed jump flash. 13+ to spot the ship itself (assuming power plant on, but sensors on passive and drives off). A ship's only going to have +2 or +3 from the ship's crew even it is a veteran sensor op on duty.

Ship's sensors are pretty crap in this edition.

 

[Shadowblayde99]

Obviously. You have a situation where the basic act of spotting another ship is overly difficult (the rules say it takes a Sensors roll without specifying a difficulty, so that defaults to 8+ before modifiers). And Stealth can give you negative modifiers that a ship has no effective way of countering that I have seen in the rules. If there are other modifiers out there, I'd love to know about them.

Though I don't know where you get -10. The rules say TL 14 stealth (Advanced) is -6. Which is still pretty overwhelming. The saving grace being it is ridiculously expensive.

View attachment 1515

Is all this in the High Guard rulebook?

 

[Vormaerin]

The basics are in the core rulebook. There's more detail in high guard.

 

[AnotherDilbert]

@AnotherDilbert
No, it is included in the stealth systems in the Update, not a separate system.

Thanks.

Ship's sensors are pretty crap in this edition.

Make sure to have some really good sensor operators, that will make up the difference.

 

[Condottiere]

Since we see everything, and there's no cloaking.

Distance and obviousness, versus sensitivity and pattern recognition.

I'd modify it by triangulation, and how many people are looking at the data.

 

[Vormaerin]

Thanks.



Make sure to have some really good sensor operators, that will make up the difference.

Yes, but the game fiction is that an experienced veteran is Skill 2 or Skill 3. And maybe a stat bonus of +1 because you put the best guys in the best training. So you can get +4? +5 if they are really high stat. We can assume that Imperial Navy will take the most apt people and intensively train them in their jobs so there is enough for those guys to be moderately common. But they are still going to have difficulty making the sensor ops check. Obviously, you can have scout ships with all kinds of upgrades to the sensors and have them hand off to everyone else (since you wouldn't want your fighting ships subject to the downsides of all those bonus sensors).

But a civilian ship can't reasonably expect to have a +5 Sensor Op nor funky advanced sensors. So if you have a stealth raider, they are probably literally incapable of detecting them unless the raider chooses to go weapons hot or really high thrust.

Most PCs have civilian ships. And Traveller chargen is designed to create reasonably rounded adventurers rather than the sort of specialists we are talking about. So I suspect most groups don't have an expert sensor op.

I personally think sensor ops is the best of the Electronics specializations, but most players tend to think Computer or Remote Ops is more exciting.

 

[AnotherDilbert]

Yes, but the game fiction is that an experienced veteran is Skill 2 or Skill 3. And maybe a stat bonus of +1 because you put the best guys in the best training. So you can get +4? +5 if they are really high stat.

Sure, that is what you can get if you really work at it, and it makes a massive difference. Perhaps even a bit more with augments.

But a civilian ship can't reasonably expect to have a +5 Sensor Op nor funky advanced sensors. So if you have a stealth raider, they are probably literally incapable of detecting them unless the raider chooses to go weapons hot or really high thrust.

Agreed, but if civilian ships with mediocre sensors and operators could see stealthed ships, stealth would be rather useless.

The Drinax Harrier with stealth and VLong range weapons is a nightmare for a cheap trader, and should be so.