Calculating maint storage

[Arwyn (OP)]

So, bit of an issue I keep running into is maintenance on smaller ships. I currently have a 6k ton patrol craft with 2 years of MSP on board, but what I keep consistently running into is repeat engine failures sending the stupid things to the repair yard. These ships currently run 2 size 25 engines, and one will fail and immediately take the MSP down to 42%. Almost immediately thereafter, the other engine pops its clogs and of course, not enough MSP and its dead Jim. Off to the yards again.

My base rule has been to keep most ships at 2 to 2.5 years of MSP, but these small ships with big engines are making a mockery of that. And yes, I know I could make the engines smaller, this was based around a ship I could put out for a year idling in a system to provide some protection. I have done this in the past with no issues (smaller engines) but these were built to be as efficient and cost effective as possible. Great idea! But their reliability has left a lot to be desired....

Now I know the short answer is more MSP. What I am wondering is if there as easier way to calculate NEEDED MSP based on the engine sizes. I have not found a good way to calculate that. If someone has a method that I am just plain missing, I would greatly appreciate any sharing of knowledge! With the proliferation of math nerds on the forum, I suspect someone has already done some arcane calculations to figure out the perfect size/cost/fuel/msp on a excel spreadsheet from hell.

[nuclearslurpee]

It's not really that complicated. The MSP to repair a component is equal to its BP cost (for normal maintenance failures; 2x if damage incurred in combat), so take the BP cost of your engine and multiply it by however many times you want to be able to repair an engine failure. Offhand, I think engine cost is nominally half the engine power, with a reduction if the EP modifier is less than 1.0x.

If it is not feasible to ship some maintenance facilities out to your system to keep this ship operating (hard to imagine, as these are only 25k tons each and don't take so much population to operate), you might consider sending a commercial supply ship with a stockpile of MSPs which can resupply the ship after an engine breakdown. Particularly at higher tech levels this could be more feasible than cramming umpteen storage bays onto the ship itself.

[Arwyn (OP)]

It's not really that complicated. The MSP to repair a component is equal to its BP cost <snip>

/facepalm

Thanks, that was staring me in the face the whole time. Now I feel like an idiot, but thank you!

[nuclearslurpee]

It's not really that complicated. The MSP to repair a component is equal to its BP cost <snip>

/facepalm

Thanks, that was staring me in the face the whole time. Now I feel like an idiot, but thank you!

If you want something more complicated, of course this is Aurora so I have it for you:

The BP cost of 1 MSP is nominally 0.25 BP (0.1 duranium, 0.1 gallicite, 0.05 uridium - assuming 1 BP = 1 mineral, which is typical but not an absolute rule). This means that fixing a failure with MSP is 25% of the cost of repairing the component in a shipyard with raw minerals. Combat/critical failure damage repair is still cheaper even with the 2x cost multiplier as it is only 50% the mineral cost.

However, not all minerals are created equal, and your economy may be in a situation such that 1 unit of duranium or gallicite is worth more than 10 units of, say, corbomite or mercassium. In this case even though the BP cost may be larger it might be worth leaving some damaged components to be repaired in a shipyard if it means conserving a more valuable mineral. For regular component failures this isn't usually important since you have no control over what fails, but when considering repairs of battle damage it can be worthwhile to leave some components damaged until the ship reaches a shipyard to conserve duranium and/or gallicite - provided you will not miss that component in a battle between now and then, of course!

None of this is relevant for engine damage since those cost gallicite to build so you almost always want to use MSP to fix them, but now you know about something complicated so I hope that makes you feel smarter. 

[Kiero]

If you don't want to calculate everything on the side:
- Create an engine prototype.
- Start new ship design.
- Look for "Max Repair".
- Add your engine, and check "Max Repair" (it should go up).

It will work most of the time, especially with large engines.

Also pay attention to:
AFR: Annual Failure Rate. The chance the ship will suffer a component failure over the course of one year
IFR: Incremental Failure Rate. The chance the ship will suffer a component failure during a single 5-day increment

Combine the two so you will know how much MPS you'll need for the desired deployment in the worst-case scenario (engine failures, since most of the time they need the most MPS to fix).

[Gabethebaldandbold]

see maximum repair msp, see annual failure rate to see how many times a year you can expect your engine to fail (worst comes to worst, you now have spent less because something else failed instead of the engine)
You should put MaxRepairCost X Failures per Year X years you want your thinghy to operate for.

[M_Gargantua]

You seem to have a lack of Engineering Spaces.  Maintenance storage helps fix thing when they break, but engineering spaces help them not break in the first place.  Look at the AFR (Annual Failure Rate) listed at the top, and see what the designer says is the maintenance lifetime with no maintenance storage.  Add Engineering spaces until those numbers satisfy you and then you can add maintenance storage to buffer the lifetime further.

[Migi]

Note that decreasing the size of the engines won't reduce the maintenance cost, assuming you also increase the power rating to get the same amount of engine power, because the cost of it is based on engine power.

I don't know the formula, but AFAIK failure rate increases as the maintenance clock increases, which is why the glossary tab uses the phrasing "during the first year after an overhaul".
Because your ships use more than 50% of MSP after a single engine failure, you can't withstand 2 full failures, and the second is more likely because the maintenance clock has increased.

To improve the situation you could increase MSP storage to withstand 2 failures, which I think would make your 'real world' results more closely match the maintenance life stat. Alternatively you could swap MSP storage for engineering space to reduce the base failure rate, but you should make sure you have enough to withstand 1 failure.

My suggestion would be to look at all the values in the class design on the line starting with Maint Life, rather than looking at maintenance life only.
 

Code: [Select]

Maint Life 0.79 Years     MSP 203    AFR 256%    IFR 3.6%    1YR 256    5YR 3,838    Max Repair 198 MSP

If you consider the example above, you can see that the estimated maintenance life is 0.79 years or about 9.5 months, and the expected usage in 1 year is 256 MSP, 26% more than it has on board.
However these comforting stats hide the fact that a single failure can drain 98% of the MSP on board. If you look at the IFR you have a 3.6% chance of the ship using all its onboard MSP every maintenance cycle, or (roughly) 6 times per month.
In this case, I would guestimate the deployment time by taking the inverse of the AFR where AFR is expressed as a decimal (so 90% is 0.9). The result is in years, so in this case 1 / 2.56 = 0.39 years, or 4.7 months. (I actually gave the class a 6 month deployment time which now seems a little long).
This way you are estimating the time for a single failure, which is effectively when the ship becomes incapable of further deployment.

[nuclearslurpee]

Note that decreasing the size of the engines won't reduce the maintenance cost, assuming you also increase the power rating to get the same amount of engine power, because the cost of it is based on engine power.

If you do it this way, then it won't help, but if you use more engines which are smaller and have the same EP modifier your MSP consumption rate will decrease, since each engine failure will consume less MSP. This is one of the reasons along with keeping down the research costs to use smaller engines, with better fuel efficiency and smaller total propulsion section being reasons to go the other way.

My suggestion would be to look at all the values in the class design on the line starting with Maint Life, rather than looking at maintenance life only.
 

Code: [Select]

Maint Life 0.79 Years     MSP 203    AFR 256%    IFR 3.6%    1YR 256    5YR 3,838    Max Repair 198 MSP

If you consider the example above, you can see that the estimated maintenance life is 0.79 years or about 9.5 months, and the expected usage in 1 year is 256 MSP, 26% more than it has on board.
However these comforting stats hide the fact that a single failure can drain 98% of the MSP on board. If you look at the IFR you have a 3.6% chance of the ship using all its onboard MSP every maintenance cycle, or (roughly) 6 times per month.
In this case, I would guestimate the deployment time by taking the inverse of the AFR where AFR is expressed as a decimal (so 90% is 0.9). The result is in years, so in this case 1 / 2.56 = 0.39 years, or 4.7 months. (I actually gave the class a 6 month deployment time which now seems a little long).
This way you are estimating the time for a single failure, which is effectively when the ship becomes incapable of further deployment.

This is good advice, it is always wise to look at all of the data points you have and tweak your design accordingly based on your needs. Maint life is always only an estimate and subject to a lot of variance based on which components break down.

[Arwyn (OP)]

Thanks for the replies. The actual maintenance life I build for is generally 2 years, which is what these ships are built for, they sit at 2.02 right now. The issue that I am running into specifically is that the large engines mean that I can lose one safely, but it takes the maint supplies down below half,  but the second engine failure results in damage, as it doesnt have sufficient supplies to repair.

Normally I dont run into this issue, as I tend to run multiple smaller engines. In this particular case, even though I had planned for 2+ years of supplies, the large size of the engines had caught me off guard since the consumed more supplies than I had planned for. The sequence was during training new ships up, one engine would fail. If I caught the message, no harm, I would resupply and life goes on. If I missed the message, then the supplies would go to 42%, and the next failure would be a engine failure that resulted in damage and a trip to the yard.

The simple solution was I should have planned for supplies based on 2 engine failures and have supplies at 20% and go standing orders, or change to have a failure drop me to roughly 20% the first time and take advantage of standing orders.