Fleet resupply

[Geoff the Medio]

Actually, I wouldn't put in the time delay

Time delay for what?

the farther you are in, the more those 'generic supply units' cost.
...
This way a massive push into enemy teritory essentially drains the economy, preventing you from building more ships to keep up the charge.

I'm fonder of the idea of declining supply rate with distance, depending on the number of turns it would take your supply ships to make the round trip (but still actually getting some supplies each turn). It just seems more logical... since when does flying a ship (even one carrying supplies) cost more PP for a longer journey?

[vishnou00]

The supply line thing could be related the maintenance cost, so a empire with all its fleets in orbit of major worlds (supply depots) would have a lower maintenance cost than an empire whose fleets are spread thin across an underdeveloped border with many fleets in enemy territory.

[Krikkitone]

... since when does flying a ship (even one carrying supplies) cost more PP for a longer journey?

well it takes more 'ship-hours' to get there which means more maintenance costs on the freighters, also there would be more 'wastage' because the supplies that are getting to the front are what we Thought you would need X turns ago, so there is some wasted stuff.

Your method of Decreasing supplies reaching them essentially is like a range limit... with the problem of the 'concept' that the player says why can't I just ship more supplies to them?

Some mix of the two might actually work. Perhaps it only Costs more as the fleet gets farther up to a point... and then the max supply levels begin decreasing as well as the cost of the supplies that Do get there increasing.

I think the main difference is that in your method, ships/forces that are at lower than recommended supply would be somewhat common. In mine they would almost never be 'unsupplied', instead empires whose economies became devoted to maintaining their invasion fleets would be common.

(Again a mix might be good, so that as an empire began overreaching, its economy would struggle And its fleet would begin to suffer penalties)

as to vishnous point, I definitely agree.. maintenance cost should basically be the cost of supplies (which would be more for ships in combat/active duty, less for mothballed ships, etc.)

[Yeeha]

Resupplying fleet should be only from planets with shipyard or somekind of building or for resupplying attacker would take nearby free planet for few turns which would ruin the idea.Resupplying would make outposts very useful(i would like outposts as in moo2 not like in moo3),outposts should be weak and expensive but should be able to supply fleet like a planet.

[Geoff the Medio]

it takes more 'ship-hours' to get there which means more maintenance costs on the freighters

This maintainance could be applied just as it would to a combat ship. Example: every supply vessel you have assigned to ferry supplies to a fleet would cost 3 PP / turn, and every one unassigned would be 1 PP / turn. This is not the same as having the cost per ship change depending on how far their trip is... if the same number of supply ships is going in both cases, the supply costs for the supply ships themselves wouldn't be any different.

also there would be more 'wastage' ...

That's kinda stretching the bounds of relevance...

Your method of Decreasing supplies reaching them essentially is like a range limit... with the problem of the 'concept' that the player says why can't I just ship more supplies to them?

It's not a range limit, precisely because you can ship more supplies to them... you'd just assign another supply vessel to the fleet.

Also, I don't expect the supply issue to limit ship range. You could always fly the ships anywhere you want. The only issue might be that you run low on supplies, so the ships don't fight as well if they get in a battle when really far away. I also expect there to be sufficient capacity to hold general supplies in a fleet that it could go for a long time without any resupply (as long as it doesn't get in a lot of battles).

Some mix of the two might actually work. Perhaps it only Costs more as the fleet gets farther up to a point... and then the max supply levels begin decreasing as well as the cost of the supplies that Do get there increasing.

I don't quite follow what you're saying... could you elaborate / give example? what's "the max supply levels"?

I think the main difference is that in your method, ships/forces that are at lower than recommended supply would be somewhat common.

As long as you put a bunch of supply ships in the fleet, and don't stay too far from your supply lines (discouraging which is the whole point), then you wouldn't have any supply problems. Running low on supplies would only be common if you habitually take big fleets behind enemy lines... which seems like a pretty good effect of the system, to me.
[In mine they would almost never be 'unsupplied', instead empires whose economies became devoted to maintaining their invasion fleets would be common.[/quote]That makes sense. (though I'm not fond of the proposal, or at least your implimentation of it).

(Again a mix might be good, so that as an empire began overreaching, its economy would struggle And its fleet would begin to suffer penalties)

Even if you really want the extra distance to cost more empire production to send supplies, does it have to be an extra penalty like this? Couldn't the cost of making a bunch of extra supply ships, and the cost of maintaining them (just the standard maintainance cost for a ship) accomplish this as well?

It just doesn't make sense to me that by producing more stuff at a planet, you can ship stuff at the same rate (in supply/turn) a further distance. To do this, you'd need more ships... and those ships wouldn't be built immediately or disappear immediately according to your current supply needs.

as an empire began overreaching, its economy would struggle And its fleet would begin to suffer penalties)

when this starts to happen should really be a player choice, shouldn't it? even better, it could require some strategic planning: building a bunch of supply ships beforehand, to keep your attack fleets supplied when far away.

maintenance cost should basically be the cost of supplies (which would be more for ships in combat/active duty, less for mothballed ships, etc.)

No objections. This doesn't necessitate a growing penalty for supplying at longer distance, though. Sitting and doing nothing shouldn't consume any more supplies if you're really far away than it would if you were sitting, fully crewed and battle ready, but doing nothing, just out of port (not the same as mothballed, which would be cheaper, if it's an option) If your fleets are all at port, you don't need to ferry any supplies to them, so you don't have to pay the higher maintaince cost for "active" supply ships, since they're all sitting around doing nothing as well.

[vishnou00]

I wondering about something pretty fundamental: does the supply ships exist on the galaxy map?

If they don't, they would be abstracted with distance. Increasing cost (for the same supply flow) over longer distance would make sense, as it takes more ships to fill that supply line, and ship would be of a rent-a-ride deal: you don't manage, you don't develop, but it's there and you pay for it.

If they doesn't, having them automated with the same rules as not apperaring ships would have little consequences, but controlling them could lead to serious micromanagement issues.


I all case, they can appear (and be protected/destroyed) in encounters they go through.

[Daveybaby]

I'd like to avoid disallowing supply ships having defences altogether. There just needs to be a soft ceiling limit making putting more than minimal armament impractical.

The risk is that people start to build missile boats with their own built in resupply capacity, which IMO totally negates the strategic gameplay aspects of resupply. If theres not a total ban on weapons then there definitely needs to be a very significant disadvantage to using supply ships in combat.

Question: Do all supply ships assocaited with a fleet appear in the battle view, or just a fraction dependent on how many would be there in a given turn (eg. 1/4 if your supply route is 4 turns log).

I thought about this, and while its not 'realistic' or intuitive, i think that all of the ships should be present during combat. Otherwise: (a) It becomes next to impossible to significantly reduce someones supply capability via combat (in which case you may as well not bother putting supply ships in combat at all), and (b) What if you only have one, very large, supply ship?

If a supply ship is damaged, but not destroyed, how does that affect it's supply performance?

I would guess that a 50% damaged supply ship would lose 50% of its supply capacity. If FO goes crazy with the damage models then you could even track damage to capacity and damage to engines (speed) separately (not my preference though).

If a stealth attack on a fleet's supply ships damages but doesn't destroy a supply ship, can that attack be followed up in later turns with a better chance to destroy the damaged ship, or will it have headed off to do some supply ferrying, thus taking it out of harm's way?

Nah, i think keep it simple - supply ships are always there in combat - if you can destroy one its gone, if not, try again next turn.

Is it possible to assign a newly built supply ship to supply a fleet if the fleet is out in the field? Does the ship have to travel somewhere under normal ship movement rules before it can start supplying, or is there some other delay (there should probably be some rule along these lines).

I would suggest that a supply ship must reach its fleet before it can start resupplying. If you have an either/or situation you start to get UI issues with the player having to decide which supply ships are supplying which fleet. Keep it simple again - supply for a fleet = the number of supply ships it has at its location.

As I mentioned in the other thread, I'd suggest tracking missiles for each ship during battle and pool supply for the fleet between battles.

Agreed.

I'd suggest a grand total of three components to supply: Big Missiles, Fighters and Generic Supplies. (No fuel, in case that gets brought up).

Well, at this stage i'd keep it flexible (since we dont know exactly what form any of this stuff will finally take is). So just have something called 'supply points' - any item, be it big missiles, small missiles, big fighters, small fighters, repair capability, fuel, food, clean underwear will take up some fraction of a supply point.

How the decision is made where to spend those supply points is another matter. I would suggest a simple prioritisation system, the player can set top level supply priorities for a fleet. e.g. set high/medium/low priorities for missiles/fighters/fuel/repair.

Actually, I wouldn't put in the time delay (because you can probably assume that any competent general would have reloads on supply ships just one turn behind the battle fleet.. on a fairly continuous basis)

I agree, no delay. Once a supply ship is with its fleet it starts to resupply immediately. Take its supply capacity and divide by the number of turns round trip to a supply depot. Thus the further away from home you are, the less resupply you get per turn from a given ship. Simple.

Your method of Decreasing supplies reaching them essentially is like a range limit... with the problem of the 'concept' that the player says why can't I just ship more supplies to them?

Well... they can. They just assign more supply ships to the fleet. What could be more straightforward and intuitive than that?

The supply line thing could be related the maintenance cost, so a empire with all its fleets in orbit of major worlds (supply depots) would have a lower maintenance cost than an empire whose fleets are spread thin across an underdeveloped border with many fleets in enemy territory.

Personally i'm not a fan of the 'economic' model for resupply. All it does is reduce everything to a cost issue, thus removing much of the potential for strategic gameplay. Too much abstraction, IMO.

I also expect there to be sufficient capacity to hold general supplies in a fleet that it could go for a long time without any resupply (as long as it doesn't get in a lot of battles).

Exactly. The whole point is that you *could* design ships with 50 missile reloads, so that they can fight an extended campaign without needing resupply. However theyre not going to be very cost/space efficient. OR you can build ships with just enough reloads for one battle, and rely on your supply ships. But if your supply chain is broken/overextended then youre a sitting duck.

Its all about making decisions, with benefits and risks on either side. The technical term for this is interesting gameplay.

I wondering about something pretty fundamental: does the supply ships exist on the galaxy map?

Yes, they exist in the same place as the fleet they are resupplying. I wouldnt expect to see them shuttling back and forth - too much detail. Keep it simple. Supply ships supply the fleet they are with. The fleet has to protect its supply ships.

[Geoff the Medio]

I wondering about something pretty fundamental: does the supply ships exist on the galaxy map?

I was thinking of a quasi-abstracted system where the supply ships exist on the map, except partly if they're actually doing some suppying.

If supply ship is servicing a fleet, the ship would appear in the fleet window, perhaps specially marked so you'd know it's not "there" in the same sense as the combat ships. If the fleet is attacked, a number of supply ships appear in the battle, roughly the fraction that would be deliverying supplies per turn. (The game could keep track of which ship is there, and which is in transit, and when each will arrive if we want... it could just be random or cycle through them each turn).

On the turns when a particular supply ship isn't actually with the fleet, it would be "en route" with supplies, and not appear on the map. There's various rules to work out concerning what to do when a fleet is completely cut off from supplies... in which case the ships could all appear with the fleet, or could stay in limbo until the fleet becomes unblockaded again. Some provision for running blockades could also be included.

There could also be situations where a supply ship is required to normally fly arcoss the map (not in limbo). The only cases I can think of are:
1) if a fleet's combat ships are all destroyed, so the supply ships are without something to supply and need to get back to their empire
2) the ship is on the other side of your empire than the fleet you want to assign it to supply. We'd need to work out some semi-consistent rules for where a supply ship needs to be to start supplying a particular fleet. The closest world is probly not a good idea, as any blockade could cause the closest world to move significantly, and there could be two nearly equidistant worlds to a given fleet, so which world you'd need to go to would be semi-random.

I don't think there's any chance of convincing people to support an automated supply / freigther network with ships flying around normally on the map, but automated. Fear of micro is phobia-esque.

[Geoff the Medio]

The risk is that people start to build missile boats with their own built in resupply capacity, which IMO totally negates the strategic gameplay aspects of resupply.

We can outlaw big offensive weapons on supply ships, but allow defensive systems (pd/shield)... (or disallow all military equipment). We could also limit the capacity to store missiles on a self-supplied missle boat, and say that the supplies "arrive" all at once during a turn (at the start), so you only have say, two missiles per turn on a self-supplied boat, which is too little to do much damage. We could also say if a ship is involved in a battle in a non-passive role, then it can't function as a supply ship that turn.

... I think it'd be just easiest to outlaw offensive weapons on a supply ship.

I thought about this, and while its not 'realistic' or intuitive, i think that all of the ships should be present during combat.

I'm inclined to agree.

I would guess that a 50% damaged supply ship would lose 50% of its supply capacity. If FO goes crazy with the damage models then you could even track damage to capacity and damage to engines (speed) separately (not my preference though).

I don't expect damage to affect speed of a ship out of battle ever... it's probly too complicated. Reduced supply capacity proportional to damage would work.

I would suggest that a supply ship must reach its fleet before it can start resupplying.

hmm... that would certainly add a big strategic issue of deciding how much supply you'll need before you leave port... We'd have to be sure to include a supply-distance-rate quickchecker though (maybe a graph?)

Keep it simple again - supply for a fleet = the number of supply ships it has at its location.

touché

So just have something called 'supply points' - any item ... will take up some fraction of a supply point.
...
How the decision is made where to spend those supply points is another matter. I would suggest a simple prioritisation system, the player can set top level supply priorities for a fleet.

Agreed. Essentially what I meant... I think.

I agree with the rest of your post as well.

[tzlaine]

I don't think there's any chance of convincing people to support an automated supply / freigther network with ships flying around normally on the map, but automated. Fear of micro is phobia-esque.

The word you're looking for is "phobic". And though I can only speak for myself, you're right -- there's no chance of convincing me of that.

I like the idea proposed earlier of there being a certain percentage of supplies that come in, based on distance to the nearest supply point. I also like the idea of being able to buy and destroy supply ships. But I want them to remain abstracted (you may know exactly how many supply ships you have, but not where they are). As I mentioned in my first post, I also like the idea of privateers and escot-duty ships. So I'd add to that the ability to explicitly buy more supply vessels, when privateers destroy them (or even in anticipation of such losses). But I think it would be best to just indicate that a fleet is X% in supply, based on where it is, the level of privateer and escort activity, and the number of total supply ships in service.

So here's my amended idea:

1) R is the supply radius of any supply point; this may change based on tech.

2) Any fleet within R of a supply point is 100% supplied, in the absence of any privateers.

3) Any fleet at distance S (where R < S < 2 * R) can remain supplied as long as there are enough supply vessels to keep it in supply; there is a certain ratio of supply ships to fleet ships that is required for 100% supply. This also assumes no privateers are present.

4) The combat value (Cp) of every enemy privateer within raiding range of a fleet decreases the supply of that fleet by Cp times some factor. Specifically, Cp times some factor should yield a supply value reduced to X% of max. This is applied to the unmodified value from rule 2 or rule 3, whichever rule is in effect. So in the presence of privateers, a fleet that is R from the nearest supply point would be X% supplied, and one that is 2R from the nearest supply point, with only half the required supply vessels (making it only half supplied based on rule 2) would be (X/2)% supplied.

5) The combat value (Ce) of every friendly escort within escorting range of a fleet restores any supply reduction of that fleet (due to to rule 4) by Ce times some factor. This means that having friendly escorts reduces the value of the X in the X% mentioned in rule 4.

6) In addition, privateers will do damage to or destroy some supply and escort vessels, and escort vessels will do damage to or destroy some privateers.

This looks complicated, but only because I specified it pretty exactly (I'm a programmer, after all).

But the implications are these:

* You can't go rampaging through enemy territory nearly as easily as you could otherwise, say based on range alone.

* You must manage the supply you, uh, supply, to your expeditionary fleets, as well as manage your total supply infrastructure (number of supply ships in service).

* You must (or at least should, if you know what's good for you) manage your escorts and privateers to maintain supply and deny supply to the enemy.

All in all, I think this could add a lot of strategic depth without adding very much micromanagement.

[emrys]

kind of like the idea of fleets having 'attached' supply ships, with the supply rate each turn being calculated as capacity of the attached ships / time to nearest supply point, as Geoff and DaveyBaby have suggested.

Each fleet could have two psuedo-groups, supply ships and escorts. I prefer the idea that if the main fleet is attacked a random fraction of supply ships and escorts close to the proportion expected to be at that location (i.e. support fleet size/turns to nearest supply point) should appear along with the main fleet, although this does prevent an opponent from taking out all you supply ships in a fight, it does still allow him to take out a fair fraction of them, and also prevents a defending player from manipulating the system to use supply ships as both chaff and supply ships.

In addition it seems to me to be a rule that players will naturally grasp, since obviously the other ships are off ferrying things, which helps build the idea that the game hasabstracted parts that are just not that interesting, rather than that's it's built on a bunch of incoherent rules flung together (n.b. not a realism argument...). N.B. when taking together with raiding supply lines, it also prevents absurdities like losing more ships than you have, since you could otherwise see situations where some could get destroyed by raiding and some destroyed in battle.

The support ships should probably not appear in battles with their main fleet at all if their fleet is the attacker, since any competant general would probably leave the supply ships behind rather than risk them if he had the choice of when and where to fight.

The supply routes of fleets could be tracked on the map (and possibly discovered by opponents by spying), by which I mean a join-the-dots line should be stored representing the shortest path to supply for a fleet, not that the movement of individual supply ships or escorts should be tracked whilst they are attached to a fleet and actively supplying that fleet.

If a fleet moved into a system (deliberately or accidentally) through which an enemy's supply route was being traced at the start of the turn, they would 'catch' a fraction of supply and escort ships, giving them a shot at attacking them and reducing the support fleet of an opponents fleet ( and possibly gaining intel on the location/size/plans of the main fleet?). The supply route would then be recalculated next turn to take account of the blockage.

We could also have abstracted 'privateering' or 'raiding' fleets, i.e. fleets assigned to operate from a given location 'on detached duty' (i.e their exact location not shown on the main map, and not under direct player control) with a chance of intercepting supply routes within a certain range. The player could perhaps set their tendancy to break up and operate in small groups, smaller groups would have more chance of intercepting routes, but also more chance of encountering more escorts than they could handle.

Perhaps these 'supply raiders' vs 'supply escorts' battles could be heavily abstracted, to reduce the number of small battles players would be involved in, but the main fleets encountering supply groups should probably be less abstract, because it would be fun to hem in an opponent's fleet in that way, and picking off small groups caught unawares has a certain malicious pleasure to it!

Although I applaud tzlaine's desire to keep things as simple and uncomplicated as possible, In this case I suspect that too simple a system may not be worth doing, and at some level of abstraction would just become a tedious exercise ("oh, he's put more money into privateers, better spend more on escorts") rather than a fun, strategy enhancing extension. On the other hand, we do need to be careful the whole thing doesn't become too overblown, or it runs the risk of being overly complex, and the extra effort to play might overbalance the fun of the extra possiblities.

I think we need to aim to devise a system which is more than just a few numbers, adds some elements of map based strategy, but has minimal things to actively manage, or to clutter the display.

[Geoff the Medio]

emrys: I heartily approve of a) support ships not in offensive battle, b) spying to discover supply routes and c) catching a turn's fraction of supply and escort ships by cutting the route. (this could also prevent the fleet whose route was cut from getting supplies that turn)

I don't think having an additional abstracted privateering mechanism is really necessary, however... the mechanism in c) above would serve this purpose. Nonlocalized attack ships doesn't appeal to me... it should always be possible to root out / destroy the ships attempting to cut your supply lines (without waiting for them to attack you to get the chance). I also strongly dislike anything that boils down to a random chance of having a battle, which it seems radius of effect or nonlocalized privateers would. (Forcing the player to autoresolve the battle and calling it 'abstracted' doesn't really solve this issue, either.)

Having supply ships appear in defensive battles away from your own systems gives a nice target of opportunity aspect. Having only a fraction show up in the battle does create the problem of partially damaged ships and what to do with them though... If the subset of a fleet's ships that's chosen for any given fleet defensive battle or cut supply line escort battle is always random, some inconsistencies will arise. A sub-issue is how to deal fairly with different sizes / classes of supply ship servicing a single fleet.

It's also hard for the player to understand why s/he is losing supply ships if it's overly abstracted. The abstraction described seems more frustrating than fun, to me (though opions may differ). At least with supply lines being cut, you can get a specific location for the ships that attacked your supplies and hunt them down.

The option to chart an alternate supply route could be available to players who are willing to take a hit in the supplies / turn to avoid enemy raiding fleets. Otherwise you end up with a supply route flipping back and forth between two nearby paths, and a single raiding fleet running back and forth and raiding the line repeatedly without recourse by player whose line is being raided.

(It should still be possible to block both paths and stop supplies completely, however... just not to exploit the shortest path algorthim)

Admittedly, AOE privateers would more neatly resolve this.

some level of abstraction would just become a tedious exercise ("oh, he's put more money into privateers, better spend more on escorts") rather than a fun, strategy enhancing extension. On the other hand, we do need to be careful the whole thing doesn't become too overblown, or it runs the risk of being overly complex, and the extra effort to play might overbalance the fun of the extra possiblities.

Well put.

[vishnou00]

Personally i'm not a fan of the 'economic' model for resupply. All it does is reduce everything to a cost issue, thus removing much of the potential for strategic gameplay. Too much abstraction, IMO.

Me too, for the same reason, but what I propose would only abstract the building of the supply ship. You pay a certain amount of whatever, and then supply ships appear from you supply depots and do the supply thing (maintaining the strategic element while removing the building element).

4) The combat value (Cp) of every enemy privateer within raiding range of a fleet decreases the supply of that fleet by Cp times some factor. Specifically, Cp times some factor should yield a supply value reduced to X% of max. This is applied to the unmodified value from rule 2 or rule 3, whichever rule is in effect. So in the presence of privateers, a fleet that is R from the nearest supply point would be X% supplied, and one that is 2R from the nearest supply point, with only half the required supply vessels (making it only half supplied based on rule 2) would be (X/2)% supplied.

It would be interesting to be able to oversupply a fleet: you ship 200% of what you need, if some privateer or other disrup the supply line, say by 33%, you still have 133% of what you need. The remaining 33% is wasted (gameplay balance thing to prevent oversupply everywhere) or not.

The support ships should probably not appear in battles with their main fleet at all if their fleet is the attacker, since any competant general would probably leave the supply ships behind rather than risk them if he had the choice of when and where to fight.

I would have they behind, but still in the battlefield. If a fleet is pierced or outmanuvered (maybe by ships specialized to do that) the fleet would lose some or all its supply ships.

Perhaps these 'supply raiders' vs 'supply escorts' battles could be heavily abstracted, to reduce the number of small battles players would be involved in, but the main fleets encountering supply groups should probably be less abstract, because it would be fun to hem in an opponent's fleet in that way, and picking off small groups caught unawares has a certain malicious pleasure to it!

Just as you don't have direct control over the ship, those battle could be full auto, where you would have a report and maybe a battle recording to show you what went wrong (who attacked, with what). Then again, I don't really like the idea of a third party (privateer) meddling in military affairs. They could be a unit bought (not built, and you don't choose the design) somewhere, directly under the control of an empire (but maybe an anonymous player in battles).

[Daveybaby]

@Tzlaine : I can see where youre headed, and agree that it would make things simpler, but IMO its not a major micromanagement task to organise supply for your fleet, any more than it is to ensure that you have enough PD ships, or troop transports.

Re: Supply ships entering offensive combat - i think that, if they are sent into the system along with the rest of the fleet then they should be in the resulting combat and thus vulnerable to attack. The player could choose to leave them at the previous system until the defences are subdued (in the same way as you might do with troop transports) but you risk running out of supply and/or having the supply ships you left behind ambushed and destroyed. Its decision/risk/benefit again.

w.r.t. supply ships running around on the map - there seem to be 2 options:

(1) Just keep all supply ships at the fleet's location. If that location is attacked, then ALL of the supply ships are present in combat, and can be destroyed. A blockade of supply routes results in no supply getting through, but no supply ships are destroyed.

Pros:
Simpler to implement.
Protecting your supply ships in combat becomes more critical, the enemy can potentially completely destroy your resupply capacity in one go, which makes for interesting gameplay.

Cons:
Not very realistic or intuitive - how are they resupplying my fleet if they never go anywhere?


(2) Have a the supply ships shuttling back and forth around the map. Only a percentage are actually located at the fleet's position at any time, with the rest being spread out between the fleet and the supply depot. If the fleet is attacked, only a percentage of the supply ships are in combat. If a system along the supply route is occupied by enemy ships, then a percentage of the ships can be attacked and destroyed.

Pros:
Makes much more sense - the player gets more of a feel for what is going on with resupply.
Supply ships can be whittled down without confronting the fleet directly, forcing the player to defend his supply lines.

Cons:
What happens if a system on the supply route is blockaded? Are some supply ships destroyed? Does this happen every turn? Or do the remaining supply ships try to find an alternate route?
If supply ships en-route are attacked, they could just retreat before a shot is fired.
Very difficult to strike a critical blow to someone's supply capacity, reducing options for strategic gameplay.
Potentially results in lots and lots of tiny boring battles.

[Geoff the Medio]

[Privateers] could be a unit bought (not built ... )

Bought from whom? Enemy empires? Conjured from thin... space vacuum, for a few billion credits?

directly under the control of an empire (but maybe an anonymous player in battles).

Huh? So a nameless players has to join the game to control everyone's privateers during battles?

I have no objection to having the option to autoresolve supply convoy raids, but it should also be an option to play the battle manually. Seeing enemy ships blow up is fun, especially when combined with the cornered-prey aspect of a poorly defended supply convoy being intercepted by some well-armed raiders.

You pay a certain amount of whatever, and then supply ships appear from you supply depots and do the supply thing

How is that any more abstracted than building the ships just like combat ships? (seriously... other than appearing at supply depots instead of shipyards... you've just very vaguely described how to build anything in-game)

I would have they behind, but still in the battlefield. If a fleet is pierced or outmanuvered (maybe by ships specialized to do that) the fleet would lose some or all its supply ships.

A good point... Having them appear in battle, though behind, also give the opportunity to set traps for fleets (get them to attack, so their supply ships are behind instead of closely guarded as they would be when defending). Also gives a role to small cloaked ships that are too weak to do much in the main battle, but could sneak around and attack the waiting supply ships from behind.

Could there be some advantage to having your supply ships appear in battle, so the attacker isn't left wondering why s/he can't just leave them a few parsecs away while dealing with the battle? Mid-battle resupply is probably too complicated / micro intensive, unless abstracted, and then it would be unstrategic... Other ideas?

Also regarding supply convoy raids, the ability to capture raided supply ships might be nice. Under the system where ships with the fleet give supplies, and ships have to be offically with the fleet to give supplies to it system, they'd then join the raider fleet, giving it supplies. You could escort them hope or to join another fleet.