Integrity Losses
Ships loose integrity each week at an approximate rate equal to their integrity mod.

Hull Type	Weekly Integrity Drop
Heavy	0.5
Normal	1
Light	2
XLight	4

Integrity decay is not linear, below 50% the chance of incurring multiple integrity losses becomes significant.

Chance of Additional Integrity Loss = ((100.0-current_integrity)^3)/25000 %

Each loss triggers another possible loss. At 10% integrity, a XL ship has a 3% chance of cascade breakdown, so it's not likely to blow too many ships up without any warning.
Ships may also loose integrity for maneuvers such as jumping, entering orbit and landing.

Other things may cause integrity losses including but not limited to traversing wormholes and entering nebulas.
Ships in battle will suffer an integrity loss daily but only lose integrity when the battle goes to 4 rounds. The amount of integrity lost is based on the ship hull type.
HH - 1 week
NH - 4 weeks
LH - 1 week
XL - 1 week
The integrity modifier based on the hull type applies to all loses. Advanced tech may alleviate some of these losses.

Maintenance restores integrity. It is conducted at a starbase with maintenance complexes.
The manifest shows how many patches are required in order to restore the ship up to 100% integrity.

Each hull type has an output value:

Hull Type	Output
Heavy	5
Normal	0.5
Light	0.1
Xlight	0.1

Cost to restore approximate weekly integrity loss in output value

QTY Hulls x Integrity Mod x Output Value
Example:
100 Heavy Hulls = 250 (=100 x 0.5 x 5)
100 Normal Hulls = 50 (=100 x 1 x 0.5)
100 Light Hulls = 20 (=100 x 2 x 0.1)
100 Xlight Hulls = 40 (=100 x 4 x 0.1)

As a standard patch is 100, this means it requires approximately 2.5 patches per week to keep a 100 heavy hull ship in peak condition.

Maintenance time will depend on patch output used by the visit and maintenance will be an order that runs until complete. It will take 1 TU per 20 mu of damage repaired used, with a minimum of 20 TU's per maintenance visit.

A 100 heavy hull ship will require approximately 12.5 TU�s (250/20) per week spent on maintenance or 650 TU�s per year � approximately 2 weeks spent in maintenance.

Note that Damage to armour and hulls will also require patches.

Maintenance can be performed manually by issuing the 'Maintenance Visit' order but if you have a ship sitting at a starbase it is possible to use 'Maintenance Options' order to automatically run maintenance on the ship when it reaches a certain integrity value.

The standard patch has an output of 100.
Higher tech patches have a higher output. They will therefore restore integrity and damage appropriate to their level.

Patch mk	Output
mkI	100%
mkII	125%
mkIII	150%
mkIV	175%
mkV	200%

The mkV patch will reduce the time to complete repairs by 50%.

All actions have a chance of reducing the integrity of a ship. The chance can range from 0% through to 100%, i.e. some will never actually reduce the integrity of a ship under normal circumstances. Each action also has a maximum integrity loss. This means that should the action trigger an integrity loss, the integrity of the ship will drop by a random amount up to the maximum integrity loss. Before this loss is applied to the ship however, it is first multiplied by the ship�s integrity modifier. For example, a ship landing on a planet may incur a maximum integrity loss of 2%. For a ship constructed out of heavy hulls, the maximum loss will be 1% but for a ship constructed out of xtra light hulls this could be as much as 8%.

Once a ship falls to zero integrity, it will break up and no longer be a ship. It will suffer an integrity breakdown and be reclassified as debris, effectively consisting of a list of remaining items. Debris can be picked up by anyone as long as they have the debris position number. No hulls or armour will survive an integrity breakdown.

Low Integrity
Even if a position has not dropped to zero integrity, it has a chance of blowing up or suffering an induced integrity breakdown but only if involved in combat or otherwise suffering damage. In combat the break down is only tested once per round when the ship was damaged.

Chance to Resist Integrity Breakdown = Square Root((Integrity/100.0)*(1.0-Damage Ratio))*100.0 %
Damage Ratio = Damage to Ship / Max Damage ship can take

If the chance to resist breakdown is less than 80% and the ship has took damage then the resistance is tested. If the ship fails then it suffers integrity break down after the combat.

Having integrity of at least 80% will ensure a good chance of avoiding blowing up in combat.

Both installing and uninstalling items will reduce the integrity of a ship. This is based on the quantity of items and not the size of them. Jettisoning the items avoids the integrity drop but has the unfortunate side effect of destroying the item. The theory is that the item is cut out, leaving the ship intact while uninstalling the item removes the installed item intact at the cost of the hull.

Due to integrity losses only ships with current integrity greater than 20% will be allowed to have items installed in them. At any time current integrity falls below 20% any further attempts to install items will fail.

Refit
If a ship is replacing items that are specified as being part of the ship in the ship�s blueprint, then a refit order will be invaluable if the ship requires many items to be installed. A refit order, conducted while in a starport will attempt to install items in order to return the ship to its original design. Presuming that the starbase/outpost has patches, these will be automatically used to counter the normal integrity loss caused by installation.

Ships can be upgraded, improving armour and hulls. Hulls and armour retain the same characteristics, i.e. Light Hulls can only be upgraded to Light Hulls mkII and Ablative Armour mkII can only be upgraded to Ablative Armour mkIII.

The order Upgrade ship can be issued by a ship while docked a starbase with 1 shipyard for every 10 hulls of the ship.

There are 3 types of upgrade
[1] Hull Size Upgrade - requires ship hulls and increases the ship size to the target hulls.
[2] Hull Tech Upgrade - requires hull upgrades items.
[3] Armour Tech Upgrade - requires armour upgrades items.

The items must be available in the starbases you are currently landed at and the ship requires security clearance via a pickup authorisation or the security code or other access.

[1] Allow the size of existing ships to be increased by up to 20% of the original BP
- 20% up to 100
- 10% after 100
- Can not increase size past 200 hulls
- Just requires the difference in hulls in upgrade patches.

[2]/[3] Allow the armour or hulls to be upgraded in mk
- Require as many upgrades as you have hulls or armour plates.
- Uses hulls/armour upgrade patches
- Hulls/armour upgrade patches BPs from the appropriate Armour/Hull techniques (mk II/III/IV)
- You can only update 1 mk at a time
- The update patches will have at least the difference in minerals between the upgrades and some production.
- It costs more production to produce a mark I ship and upgrade to mark II than creating a mark II ship from scratch but less production than scrapping a mark I and producing a mark II (based on average reclaimed patches from salvage).
- Upgrading will increase integrity to 100%.