Minefields in VGAP4

This page last updated Feb 2007. Latest section is Gabor's theory on minesweeping by ramming. Author: Paul Honigmann. Thanks to Tim, JoSch, Andreas Benne, Frank Kohlbrook, Elminster, Darkmoor, Porthos, Hilmar Benne, Lord Dago and Gabor for help with this page!
See also: the official Help files page on mines

Basic facts about mines

There are several types of mines: Barbitic (often abbreviated to "barb"), essentially "normal" mines; Laser mines, good against fighters but only marginally useful against anything else; Gravitonic ("grav") mines, useful against hyperjumping ships and fairly useful in general; Web mines, which do little damage but essentially trap you in glue; and Nova mines, a Robot speciality (like a super-barbitic mine). Energy Mines are a kind of Large Weapon.
Cloakers do not have a reduced chance of hitting mines. The chance depends purely on a ship's speed.
Minefields can be "cloaked", which turns off their function as mines but makes them difficult to see. This is the basis of several trap tactics, where people lay cloaked minefields around a valuable target and detonate them all together if enemies arrive.
All races can sweep cloaked mines with a 25% success rate (Host 193)
You can't add mines to already laid minefields, i.e. enlarge a field by adding mines; you always make a new (overlapping) one.
You can recharge minefields using the REC command code. This is useful because minefields have a finite life - about 20 turns. Example: a mine laying ship which is set to lay mines, but has this command code, will recharge a minefield within 200LY which is about to expire, back to a lifetime of 20 turns. This saves a lot of micromanagement, driving ships around to re-lay minefields.
If you lay more mines than are allowed - i.e. if max minefield radius set by the Host is 30 LY and you attempt to lay a 40LY one - then you seem to get TWO minefields in one turn. The excess mines form a second, smaller field with the same centre.
If you know a race's UFC (Universal Friendly Code), then you can use it as a ship's Friendly Code to move through their mines as if you are that race - ie you are immune to their mines. (It doesn't stop Grav Mines knocking you out of hyperspace though.) The Bird race can sometimes find out your UFC so don't assume mines will always work against them. If you ally with Privateers, they get a mail from Host.exe with your UFC.
Unlike VGAP3, you cannot allow allies to pass through a minefield by setting the minefield's Friendly Code. Nor do nearby planets' Friendly Codes matter. It is simpler than that. You simply switch off the ATTACK switch for them in your Race screen, (ie: set a non-combat alliance) and your mines will not hurt them.
As a rule of thumb, a ship of 200kT mass or greater can survive a single mine hit. Ships under 100kT will always be destroyed. Swarming races (small cheap low mass ships) have problems with minefields.
If a cloaked ship takes 25% system damage it can no longer cloak.
Web Minefield radius = Ord ^ (0.45)
Other Minefield radii = Ord ^ (0.40)
Minefields list density level on minefield display. A minesweeper can only remove one density level a turn. A density 2 minefield acts like two overlapping minefields.
The Glory device now destroys all space mines within 50 LY. It destroys both cloaked and non-active mines. It destroys all types, including web mines. It is a good area-effect minesweeping device, if expensive (one ship per pop!)
Hitting a grav mine during normal space movement damages the ship's hyperdrive. Damage to hyperdrives keeps them from working.
You can move through Barbitic / Grav / Laser minefields safely at speed 13 or less. And as long as speed is under 26, you only have 1/3 hit probability on Barb, Laser and Grav Mines.
You can move through Web fields safely at speed 6 or less.

Sweeping minefields

Mines are not swept by beam weapons, like in VGAP3.
They can be swept by the following methods:

using the Mine Sweeper device found on specialised ships, at the rate of one mine field per turn. NOTE: this is about the only part of the game where ship experience has any effect. If a minelayer and a minesweeper both have their devices turned on, then the minelayer usually lays after the sweeper, trapping them inside a minefield next turn. However if the sweeper has a higher experience, it acts after the minelayer and sweeps the newly laid minefield. This fact is immensely useful when a fleet is advacing into thick enemy minefields.
(Having your mine sweeper device turned on makes 50 units of sensor image noise and reduces your scan range by 50%. This is significant for cloaking ships.)
Alternatively if you have the Mine Field Destabiliser device, it has an 80% chance of sweeping one field per turn at a distance of up to 150LY. If it fails to destroy the first one it finds, then has an 80% to destroy the next one and the next one. . . It can only destroy one minefield a turn, it makes no sensor noise. It can destroy cloaked and inactive mines (except cloaked barbitics). It will destory your own mines. It does not sweep Webs.
The Glory Device, found on some ships (noticeably two Stormer hulls, the Peoples' Army Martyr, and a hyperjumping Centaur one), will clear all minefields whose centres are within 50LY of its detonation point, even if they are cloaked. It is a popular method of clearing paths through walls of mines.
Another technique is to overlap a barbitic or Nova minefield with the centre of the field-to-be-swept. Detonating the Barbitic / Nova field destroys any minefields whose centres are within it. See the Crystal page / anti-Crystal tactics re: damage to ships caught within detonating minefields.

If you are attempting to sweep minefields, the owner might detonate them; detonation happens before movement and mine sweeping, so if you are inside a minefield you are in trouble if the owner notices you. However, the damage from laser and barbitic mines is so slight you can ignore damage from them detonating.

Laser and Grav mines can be swept even if they are cloaked.

Only the Robots can sweep cloaked Barbitic or Nova mines.

(Host 193:) All races can sweep cloaked mines with a 25% success rate

How to sweep minefields with pods:

Lord Owl mentioned this tip as he and I were battling versus a Robot. I am awed by its lateral-thinking cleverness, though he tells me he did not think of it. Each pod will cost 25mc but I imagine it is still cheaper than losing a ship:
> > >I am sweeping novas now with hundreds (!) of supply pods (filled with 1 precious med).
> > I don't understand how you can do that..?! Sweep with pods?
> Hitting minefields. Each pod that gets hit substracts one power from the minefield (as does any object hit by a minefield). Powercheck at end of turn deletes a minefield if it has power 0.
Note that like a photon, pods have a natural non-zero speed of 20 or whatever even after being brought hitting Webs. If they get caught in Webs, gravs or laser mines they don't get destroyed: they keep restarting their trajectory and draining the minefields for many turns, so they're surprisingly cost effective.If the Webs disappear they sail on. One pod can drain energy from minefields turn after turn. Unless it hits barbs / novae and blows up.

How to sweep minefields with wings: Use lots of minimum sized WIngs (size 10) going at maximum speed (to increase chances of hitting mines). Don't load HG on the Wings. The WIngs might lose 1-2 fighters per barbitic / grav mine hit, but they can drain the power of Web, Nova, Grav and Barbitic mines several times before dying. Refuel by finishing at the same point as a ship at the end of each turn. Don't try this on Laser mines. End the turn outside the minefields as exploding novas and barbitics can do a lot of damage to wings.

A refinement: Thriyon reports that RCS Poppy fighters - which are immune to laser mine hits - can still be used in this manner to sweep laser mines, and (on at least one occasion) Novas, without taking losses.

Sweeping by ramming
G Teroe did some maths after the mine damage reductions in Host 198 and discovered that ships of sufficient mass, ie >400kT, can now sweep barbitic mines simply by barging into a minefield and deliberately hitting as many as possible. For example a ship travelling at top speed might hit 9 mines in a turn, and be able to repair all the damage at the end of the turn. Use 2 or 3 such ships and you drain the minefield of energy in one turn, so it cannot be recharged by a nearby minesweeper.
Personally I'm sceptical that this is entirely safe, or that you can repair the damage that quickly, but here's the maths:

[Gabor writes:]
This is what you can currently find for minefield hits during motion thru a BMF:

m6_MineOdds(id) = Hull.Stealth + 200
...
rOdds1 = m6_MineOdds(id)
rT = VectorLen(id)
rOddsM = g_fig(5)
rOdds2 = (rT + 1) ^ 3 * (rOdds1 / 100) * (rOddsM / 10000)
If rT < .13 Then rOdds2 = rOdds2 / 3
IF rT < .066 THEN rOdds2 = 0

# 100% hull damage to 100kt or less ships.
# Hull Damage: (100 / Ship Mass) x (Random Number between 0 and 150 + 130). New to host 198: Ships with a hull mass of over 400kt take less damage from Barbitic mine hits, maximum damage is now ((100 / Mass) * 80 * Rnd.

The are some questions which arise with this data:

1) "100% hull damage to 100kt or less ships.
(100 / Ship Mass) x (Random Number between 0 and 150 + 130)."
The first sentence suggests, that there is over 100kT hull mass a chance not to get 100% damamge or more due to a single mine hit. But (Random Number between 0 and 150 + 130) is at least 130. So up to hull masses of 130 you get always more than 100% hull damage due to a single hit.

2) "(100 / Mass) * 80 * Rnd"
This is a hull damage of 4000/(hull mass) in the mean. So a 500kT hull get 8% per hit. A 1000kT ship 4%. A Cube 1.6%, an Enforcer Dreadnought 1.33%, a Nexus 1%.

So unless the odd are not too high, even for middle sized ship barbatics are as if they were not there. What are then the odds?

3) rT in the former formula should be the vector length of the travelled way per movement tick. So it is Speed/200. g_fig(5) are the barbatic mineodds (15). hull.stealth should be the warpsignature parameter of the hull (shortly called WS).
Then the formula for the the odds of a mine hit during a single movement tick reads
3/200000 * (WS+200) * (1+Speed/200)^3
If the ships has to go the distance of L thru the MF then it spends L * 200 / Speed movement ticks within the MF.
So in the mean there are
3/1000 * (WS+200) * L/Speed * (1+Speed/200)^3 mine hits
And finally such a over 400kT sized ship gets in the mean this damage:
MeanD(WS,HullMass,Speed,L) = 12 * (WS+200)/HullMass * L/Speed * (1+Speed/200)^3
Lets take a Cube (my favourite standard test Dreadnought):
hullMass=2500, WS=70, L=300 (e.g. 10 overlapping 5000er barbatics), Speed=190
MeanD=12*270/2500*300/190*(1+190/200)^3 ~ 15 %
Wow! A Cube at full speed runs throu 300Lj barbatics and only gets 15% damamge in the mean. Respect, respect!
The mean number of hits it suffers is:
MeanHits(WS,Speed,L)=3/1000 * (WS+200) * L/Speed * (1+Speed/200)^3
For the former example this is a mean of 9.5 hits.

So who needs mine sweepers anymore? Just send heavy ships moving arround and arround within a minefield and it is cleared. We laugh about the damage! It is so small that we can fully repair after the end of the turn!

BTW: If you spend all the time in the MF then L=Speed and you see that for speeping purposes the max speed is the best...

Detonating minefields

All detonating minefields explode before movement.
(Warning: exploding minefields zap your own ships within them!)
A detonating barbitic minefield used to kill some fighters in a wing, though not usually all of them like a laser minefield does. But Tim stated in a recent newsgroup email that Barbitic fiields do not do this. Host change or a bug he is ot aware of?
Nova Barbitic mines do twice the normal damage that a Barbitic does when it is detonated. A standard Barbitic will do 22% hull damage to a 100kt mass hull ships and a Nova Barbitic will do 44%.

Damage from being inside a detonating barbitic minefield: Hull damage = 2000 / (hull.mass + 1) + 2
System damage = twice the hull damage

Increasing damage by overlapping minefields

Overlapping is useful if you are protecting a valuable point such as a homeworld or jumpgate. If enemies converge on it, you can do lots of damage to their entire fleet if you can catch them in several simultaneous minefield detonations.

However, it is tricky to get the minefields to overlap in the optimum way - i.e. so that you can blow them all up without wasting any (because if the centre of one is inside another which blows up, it will be destroyed before it can detonate and damage the victim; and Host.exe is written so that the minefields blow up one at a time, not simultaneously). If you have, say, 3 barbitic minefields over one spot, and you detonate one, it removes both others. You could have 200 minefields in one spot and one mine would blow them all. (This is also a standard tactic for sweeping mines.)

A little trigonometry will show you that it is impossible to overlap more than 5 minefields in one place. So you will often see Jumpgates, Homeworlds and other strategically iportant points protected by a little rosette of 5 overlapping minefields.

How to overlap minefields

Shipcalc.exe is a utility which includes a "minefield calculator" which will help you position minefields optimally.

Damage from running into a barbitic minefield:

Hull Damage = (100 / hull_mass) * (RND * 100 + 100) // RND is a number from 0 to 1
IF (RND * 50) < Hull_SoftSpot THEN Ship_DamageHull = Ship_DamageHull + (RND * 200) + 20

Note: no one's ever seen a big ship destroyed by one mine hit, so I don't know why there is a reference to Soft Spot here - PH

Removed from this document: host code fragment about barbitic mines, dating from 2002. Host mine code was changed in 2003 and again in Host 198, and probably in between. I refer you to the Wiki for more up to date code if you are interested.

However the code revealed some interesting consequences. The relevant items are:

Warrior shuttles are immune to minehots if they carry a High Guard
Ships are immune if they are within 10LY of a Virgo carrying High Guard and Wings - it's not clear from the code that they need to be owned by the same person with the Virgo! Might be a rule loophole to exploit there, if anyone can be bothered to test it...
A ship's scanner profile is increased by 800 if it hits a mine
Host 198 toned down Barbitic damage: Ships with a hull mass of over 400kt take less damage from Barbitic mine hits, maximum damage is now ((100 / Mass) * 80 * Rnd

Interesting consequence of the maths - how to minimise chances of hitting mines

Way back in December 2002, Gabor Törö did some number crunching on the odds to hit mines. He noticed that a ship flying at 90LY through a 25LY thick barbitic minefield had nearly 80% odds of not hitting any mines. That means 4 of 5 ships travel to the center of a 50LY diameter field and get no hit? Could that be?

Gabor wote: "I calculate the odds to be about 30% to hit at least 1 mine. The formula USED to include (rt+1)^2, but I believe it's now ^3. Look at the host changes...

"If we use grav mines instead of Barbitic... the chances jump up to 61%. Laser mines: 85% Web mines? 98% !!"

Roger Norris explained it thus: "Oddly enough...cutting your speed in half, to 45, actually INCREASES your chances of hitting a mine in this case (to about 35% for barbitics)! The reason is because you're inside the minefield twice as long. Host does the mine hit calculations every movement phase, not every lightyear... the increased number of chances to hit a mine (2x more chances since you're going twice as slow) more than makes up for the decreased chance of hitting a mine during every movement phase.

"It looks like the optimum speed to go through any minefield is about 93, except of course for the speeds at which you can't hit minefields :)

"The WORST speed to attempt a minefield at is one higher than the minefield immunity speed."

I (Paul Honigmann) haven't been able to find anyone who KNOWS if that is correct, so I tested it with Host 193 in a scripted game: I found:

Crossing 76LY of a barbitic minefield,

8 / 8 Fed Vendettas travelling at speed 93 were destroyed. Doesn't seem very safe to me!
22 / 26 Fed Vendettas travelling at speed 45 were destroyed. They only crossed 45LY of the 76LY of course - this was in one turn. The remaining four may well have died too, except the minefield ran out of energy after being hit so many times! Still not very safe.

So personally, I think I'll be sticking to low speeds, or big ships...

Special racial abilities with mines

The H Ross and RU25 Ships (Evil Empire) are highly resistant to minefield damage. These ships only take around 10% normal damage for a ship of its size when hitting a mine. Groups of H Rosses can be more-or-less-safely HYP'd into a minefield area with their minesweepers switched on, to sweep several minefields at once.
The RCS Maelstrom hull has the same powers as the H Ross. (Or possibly full minefield immunity. Thriyon reports repeatedly sending them through layers of laser minefields at full speed and never hitting one. Have asked Tim for clarification.)
Scavengers in their own ships can travel safely through Grav + Barb + Nova mines. Lasermines have normal power on them and webmines double power.
Exploding Enforcer grav mines do 25% system damage
The Aczanny Sparrow Class Scout is immune to Grav+Barbs (tested), I have heard this is true even if it owned by non-Aczanny.
Any ship owned by a Crystal player can travel through a web minefield without any danger of hitting a web mine (according to the documentation).
Any ship built by a Crystal player can travel through a web minefield without any danger of hitting a web mine even if owned by a non-crystal race (according to the documentation).
Crystals are immune to damage from detonating web minefields (read it).
Crystals are immune to the effects of hitting web mines.
Si-90 Poppy Strike Fighters (Fighter 3 of the RCS) can fly through laser minefields - but this does not include immunity to a detonating laser minefield. That still destroys them. (Checked by Thriyon in 2004)
Virgo with a Wing and 1 Hg on board give minefield immunity to all ships of the owner of the Virgo within 10LY. It must be owned by the CoM for this to work. This permits the CoM to fly entire fleets safely through minefields.
The Warrior Shuttle is immune to mine hits if it is owned by the CoM and carrying High Guard
The Privateer MCBR takes 2X damage from detonating Barbitic minefields, (Normal damage if it hits one) (read it)
Aczanny and RCS can only lay Laser never others (read it).
The Robots are the only ones who see and can sweep cloaked Barb and Nove Mines (not tested). No longer true - see host 193 changes. They can now sweep them 25% of the time, so can everyone else.
Under the latest rules, Robot mines are always active, visible and sweepable. Robots are no longer allowed to cloak mines. As a consequence, Robots can't HYP through their on mines do Novae block hyperships? (not that they have HYP ships anyway - and they can't clone other races' hulls - so not much of a problem). New, Host 193: Robots can cloak mines
Robots are almost immune to detonating Barbitic and Nova mines.

Nova Mines

Fighters are immune to hitting Robot Nova Barbitic mines. (Though possibly not to detonating Nova fields.)

The big thing about Nova mines is that if you have a fleet inside the radius of a number of normal (barbitic) minefields and they are detonated, your ships only get damage from one minefield. Unless they are Novas. So if your fleet is tricked into entering overlapped Nova mines, it is almost certain to take very heavy damage. Luckily Robots have slow ships and use mines mainly as a defensive tactic!

Nova Mines are like combined Barbitics and Grav mines. Ie, they block hyperjumps. Since Robots can't turn them off (cloak them), it is almost impossible to HYP across Robot space. That's been changed in Host 193. Robots can now cloak them.


Nova damage Algorithm (mentioned by Tim on Newsgroup, June 2004) A 500kt ship should take 12% damage from a Nova Blast. hull damage = 2 * ((2000 / (hull.mass + 1)) + 2 ) It will case this much system damage: system damage = 4 * ((2000 / (hull.mass + 1)) + 2 ) A robot ship of any size takes only 3% hull damage from a Nova Mine

Web mines (discussed in more detail on the Crystals page, under Race Abilities. )

Web mines do 20% engine damage f you run into one, and your ship comes to a dead stop in space.
Unlike VGAP3, Webs don't drain fuel every turn you are inside a web field. The Cystal race instead uses their X Field device to drain Repair Units from nearby ships. It's more complicated to use than VGAP3, if you are a Crystal player.
Webs stop all pods, ships and Wings unless they are travelling at 6LY/turn or less.
Web mines do 10% engine damage to stationary ships if the Web field is exploded. Sitting in a web field does no damage to your ship.
If you detonate overlapping Web minefields, they do not destroy each other. They each do 10% engine damage. In this way the Crystals can do extreme engine damage. Their X Field will capture ships with >100% engine damage.
Unlike VGAP3, Webs can be laid by anyone if they capture a Crystal ship.
Flying through Web minefields increases your visibility. Every phase that you are in a web adds (Phase_VECTOR * 5) + 1. If you are going speed 100 you will gain 3.5 noise units a phase.
Host 198: Ships with a hull mass of over 500kt can crash through web mines and only have a 10% chance that a web mine hit will stop the ship

Grav mines

Grav mines knock ships in hyperspace, out of hyperspace.
You cannot HYP out of an active (uncloaked) Gravitonic Minefield. Even your own! You will hit your own grav mines. Even if you set your Friendly Code to your UFC. It's not a bug - it's what they're meant to do. The owner can turn the grav mines off, but not make them semi-permeable.
Rebels have difficulty detecting grav mines. Mivorari grav well defuser disables grav well generators and grav mines in the area
Grav Mines have 2.6 times more likely to hit an enemy ship, than a barbitic.
Grav Mines do 1/10th the normal damage of a Barb Mine damage(max 10% damage)

Laser mines

Laser mines can be swept even if they are cloaked.

Laser Mines are 5.2 times the barb mine chance to hit an enemy.
Laser Mines will destroy a random number of fighters.
Laser Mines can do heavy damage to ships under 60kt.
Laser Mines can do no more than 3% damage to ships over 100kt.
Laser Mines raise the warp sig of the unit striking them by 20%.
Exploding laser minefields destroy free (undocked) Wings within them, of whatever size.
Exploding Laser minefields increase the sensor image of whatever is inside them by a huge factor.
The RCS type 3 Fighters are immune to hits from lasermines. Only exploding lasermines will destroy them.

Just how obsessive can you be about minefields?

Here is an extract from the newsgroup, March 2006. Kaos asked a question about Gravitonc Mine Fields (GMF's) and Gabor Toeroe replied -

To setup a fast GMF protection I use to lay a few GMFs at max radius in all directions with respect to the point which is to be protected. Theses MFs are as close as possible to the point but do not cover it. This way if you deactivate or cloak one of them you only open a small sector.
And later after a while I lay a ring of small GMFs of radius of 12 at a distance around the point which my fastest interceptors can reach till tick 50 for example.
Then you only have to open one of this small GMFs to let your forces hyp through while blocking almost all hostile jumps.
And very later a second ring of small GMFs decreases the chance for a successful hostile hyp through even more...

Screenshot from a game showing excessive minefield laying by some players

Thinking of games I've played with Germans (see typical screenshot, right) I had to say -
>What is it with German players and minefields? They all lay precision matrices of them - a thing of wonder and beauty to behold upon one's scanners - I always marvel at German minefields.

(Kaos:) > And I thought I was being particular by drawing my proposed rings of protective minefields in CAD to determine the proper co-ords for my points in space.
Clearly I am an amatuer compared to the greats.

Gabor again -
> It is no attribute of the German's itself although some of them use excel sheets to lay their MFs. I used to do it the same way till I recognized that you can do it with the client very easily:

Example: You have a minelayer which is intented to lay a ring of overlapping 500er MFs at a distance of 100 lj arround a single point. The diameter of such MFs is 24. So you choose a distance of 20 for neighboring MFs. Take the minelayer and send it to to point which has a distance of 100 to the point which is to be protected. Then set a second WP back. Give the minelayer a speed of 100 and order it to lay a 500er MF with an activated repeat switch (disable magnetic waypoint option).

Next turn the 1st MF is laid and the minelayer has a WP back to the center. Now change the speed to 20 (disable magnetic waypoint option) and take the little blue triangle in the middle of the WP line and drop it at a location where you assume the next correct position of the minelayer, that is a location which is 20 lj away at a distance of 100 to the center and make a few fine corrections. Make sure that the HUD is activated to check the path lengths to each WP. Repeat this procedure until the ring is closed. This way ou get without any excel sheet an almost perfect circular ring of MFs. without geat affords. The only thing you have to do from turn to turn is to set via the colored WP triangle a new 1st WP.

This example can be extended also to regions which shall be protected by an effective wall of MFs.

And in general: If you use all the six possible WPs and "points in space" (not bouys) one can construct the needed WPs for perfect geometries without external help.