Cost of owning vehicles/equipment - Optimal time to replace - Detailed cost analysis

[humbe]

...With the exception of usually poorer lighting, transmission options, and slower max speed, classic tractors are usually the best HP/$ value you can get in game.

Yeah.. A lot of the reasons why real farmers will prefer modern gear isn't reflected in the game. Only thing I can think of is if you play with a manual gearbox, I'd be willing to pay quite a bit extra for a Fendt Vario or some similarly nice transmission

[NDDan]

Thanks for the positive comments

Added a portion on used vehicles above. They are truely a bargain, as, possibly a bug, cause initial price to be set to the used price, so they are really cheap maintenance wise.

Yes, this is strange. If you buy something used for 50% off, the value of it immediately becomes 50% of what you just paid for it, so it’s already down to 25%. I agree that this seems like a bug.

Thanks for your great analysis.

[humbe]

...
Yes, this is strange. If you buy something used for 50% off, the value of it immediately becomes 50% of what you just paid for it, so it’s already down to 25%. I agree that this seems like a bug.

Thanks for your great analysis.

Yes.. You buy something that already has age and operation time on it, which reduces sell value below the initial 12% of a new vehicle. The sell price mechanics are the same, so thus the value loss is more than 12%. Also, they typically already have paint damage and needs repair, and you don't get to know paint and maintenance condition before you buy it, so the real cost is a bit more due to having to repair it immediately to. The paint state doesn't really factor in as it wears of so fast anyhow.

One would think that if they kept the initial price as the new price, then the sell value would be correct, far less than 12% of what you bought it for, but it seems the buy value is far below what you can sell it for, so if that was the case, you could buy used gear, repair and repaint and then sell it with gain immediately. I guess that might be why they put in the rebated price there, because the sell value is too good to be true

Oh.. And a note about the operation time cap of 50 hours before maintenance cost stops to increase further due to time used. I'm starting to think, as this drops of fairly quickly, that this is intended to just be a mechanic to indicate that new gear doesn't need much repairs.. And getting to the cap just means, now the vehicle is no longer new, so you're in steady state and will have to start replacing components as they wear out and so on.

I don't object with the price of maintenance after figuring out the details, but would be nice if they could increase the time interval between repairs and rather take more for each repair, so you at least could run through a few diesel tanks between each repair. Also.. Would be good to flatten the curve to begin with, so the optimal time to repair was at like 30-50% state rather than as soon as possible and as often as possible.

[george.earlslight]

Hello, first off all thanks again for your effort on analyzing the maintenance game mechanics.
Out of respect for your work I've decided to post my own findings as a reply to your thread, commenting where I managed to make improvements.
I've split the analysis in parts.

Part 1. Damage taken over time

This is what I've found to be a very peculiar game decision by Giants, and a downgrade of previous game versions.
Vehicle damage accumulates as long as there's a driver on a vehicle (player or AI).
It doesn't matter if you turn the engine on and idle, if you're pulling a 20ton cultivator over mud, or just chilling admiring the views engine turned off.
As long as you're tabbed in a vehicle, it gets damaged.
Paint does get degraded depending on work and whether being on a field or on road.

Now on to the math.
Your formula is accurate as to the instantaneous damage rate. I'm going to add that it's also depended on a constant found on each vehicle's .xml

Code: Select all

<wearable wearDuration="480"

All base game vehicles have a wearDuration of 480 and it anyway doesn't have much influence on the final result.
A value of 48000 would lower the damage rate by 25%.
As such, the formula approximation is the following

Code: Select all

damageRate = (0.35 / (wearDuration/60))+(0.00298*operatingHours)

The rate increase does cap at 50h, as you've mentioned.
It seems that the rate is a bit off as operating time increases, so there's probably more to it in the actual ingame formula.

Now I'm going to jump for a bit to your final conclusion.
When calculating monthly damage, it seems you've made your calculations having a constant rate of damage over operating time.
This is not correct, as the rate is not constant. You need to integrate over the range of operating time.
We could integrate using the analytical method, but this is not how the game works.

The game engine calculates the new damage on every update tick and sums it up.
This is similar to calculating an integral using approximation.

I've written a python script to calculate this.

Code: Select all

def damageRate(wearDuration, operatingTime):
    if operatingTime > (3600*50):
        operatingTime = 3600*50
    return (0.35 / (wearDuration/60)) + (0.00289*(operatingTime/3600))

def damageDone(wearDuration, operatingTimeStart, operatingTimeEnd):
    totDamage = 0
    simTime = operatingTimeStart   
    while simTime < operatingTimeEnd:
        damage = damageRate(wearDuration, simTime) * (1/3600)
        totDamage = totDamage + damage
        simTime = simTime + 1
    return totDamage

for optime in range (1800,54000,1800):
    print(damageDone(480, optime-1800, optime))

The difference here is not trivial, as your results can be 15-20% less on the monthly maintenance cost and this is accumulating fast.

The results are very close to what is stored in the vehicles.xml <wearable damage>

[george.earlslight]

Part 2. Cost of repairs

My findings match yours exactly.
The formula seems correct as

Code: Select all

0.09*(damage^1.5)*price

I agree that this is overly simplistic, but I will summarize my comments on the last part.

Some more python scripts for testing.

Code: Select all

def repairCost(price, damage):
    return (0.09 * pow(damage, 1.5) * price)
    
def repairCostOverTime(price, wearDuration, operatingTimeStart, operatingTimeEnd):
    return (repairCost(price,damageDone(wearDuration, operatingTimeStart, operatingTimeEnd)))

[george.earlslight]

Part 3. Devaluation

As you've mentioned, its clear that equipment loses value depending on operatingTime and age.
I've managed to calculate the individual part very close to the actual results, by keeping each part at zero one at a time, but the final result seems off.
Again, it seems there's something more in what Giants uses in their code.

Operating time devaluation is perfectly exact, as you've mentioned.
My addition to your findings is that I'm assuming Giants is caclulating always on the initial used price, the price with the 12% deduction.
So I've drawn my plots accordingly and it seems the formula is an exact match, along with what is probably written in game code.

Code: Select all

usedPrice=0.88*price

Code: Select all

sellPrice=(1-(5/3000*operatingHours)*usedPrice

I've also managed to find the devaluation by age formula.
The value loss factor exactly matches the logarithmic function. Again, the plot is over the usedPrice.
Devaluation starts at 8 months in, anything less and the price is the initial used price.

Code: Select all

sellPrice=(1.25-(0.125*ln(age)))*usedPrice

I'm having a constant error, which I didn't manage to find the source of.
Adjusting the function to

Code: Select all

sellPrice=1.25-(0.125*ln(age))-0.00189)*usedPrice

seems to completely eliminate the error.

Now plugging in both factors, age and operating time, should result in perfectly predicting the sale value.
But it's not. As age and operating time increases, it seems that there's also more to the formula. I didn't put much effort on trying to find out what's up


Python script

Code: Select all

def sellValue(price, age, operatingTime):
    usedPrice = price * 0.88
    
    if age > 7:
        ageDevaluation = 1.25-(0.125*math.log(age))
    else:
        ageDevaluation = 1
    
    useDevaluation = (1-(5/3000*operatingTime/3600))
    
    return (usedPrice*ageDevaluation*useDevaluation)

[george.earlslight]

Part 4. Deciding when to replace

Now this is the part where I'm trying to answer my initial question.
Could there be an optimal time to replace your equipment?

The short answer is it doesn't seem so.

But there can be a time when it's almost the same cost.
It's dependent on something most players don't know when playing, how many ingame years one is going to be in a single map.
Playing a map for 8 years, 10 years or 12 years, are all going to produce different results.
The other input is how many hours the tractor is going to work each year.
This is probably easier to predict, once you've played the game a bit.
My tractors are used about 12-16h per year.
One concession I had to make is to calculate the repair intervals as if repairing each work hour.
This is not something I always do, but it fits my play style the closest.
The python scripts can be adjusted to change the repair interval or restructured to repair at specific damage percentage.
Repairing at specific damage is not something I personally do.

On to the methodology, we first calculate the cost of ownership of a tractor we never replace.
As we plan to keep it forever, its sell price doesn't matter.
We only care about the increasing cost of maintenance.
Here's the script and an example result for the Fendt 1038 and playing on the map for 10 years.

Code: Select all

#assumes repair every hour, wearDuration = 480 as per Giants base
def costOfOwnershipKeep(price, opHoursPerYear, yearsToRunSim):
    sumCost = 0
    for hours in range (1, yearsToRunSim*opHoursPerYear):
        #print("--- Hour ", hours, "---")
        hourCost = repairCostOverTime(price, 480, (hours-1)*3600, hours*3600)
        #print("Hourly Cost ", hourCost)
        sumCost = sumCost + hourCost
    #print("---= Keep the equipment =---")
    #print("Total operating Cost ", sumCost)
    return sumCost
    
costOfOwnershipKeep(329000,16,10)

	Code: Select all --- Hour 1 --- Hourly Cost 284.4907877464182 --- Hour 2 --- Hourly Cost 312.210424689934 --- Hour 3 --- Hourly Cost 340.77610086327354 --- Hour 4 --- Hourly Cost 370.16346281333176 --- Hour 5 --- Hourly Cost 400.3501468940273 --- Hour 6 --- Hourly Cost 431.3155221572384 --- Hour 7 --- Hourly Cost 463.0404774908134 --- Hour 8 --- Hourly Cost 495.5072436679148 --- Hour 9 --- Hourly Cost 528.6992432725746 --- Hour 10 --- Hourly Cost 562.6009631254026 --- Hour 11 --- Hourly Cost 597.1978450489814 --- Hour 12 --- Hourly Cost 632.4761917158634 --- Hour 13 --- Hourly Cost 668.423085002493 --- Hour 14 --- Hourly Cost 705.0263147908387 --- Hour 15 --- Hourly Cost 742.2743165590208 --- Hour 16 --- Hourly Cost 780.1561164132092 --- Hour 17 --- Hourly Cost 818.6612824573699 --- Hour 18 --- Hourly Cost 857.7798815910962 --- Hour 19 --- Hourly Cost 897.5024409804498 --- Hour 20 --- Hourly Cost 937.8199135713081 --- Hour 21 --- Hourly Cost 978.7236471156625 --- Hour 22 --- Hourly Cost 1020.2053562637218 --- Hour 23 --- Hourly Cost 1062.2570973423353 --- Hour 24 --- Hourly Cost 1104.8712454961305 --- Hour 25 --- Hourly Cost 1148.0404739141677 --- Hour 26 --- Hourly Cost 1191.7577349036646 --- Hour 27 --- Hourly Cost 1236.0162426048291 --- Hour 28 --- Hourly Cost 1280.8094571682661 --- Hour 29 --- Hourly Cost 1326.131070239554 --- Hour 30 --- Hourly Cost 1371.9749916153376 --- Hour 31 --- Hourly Cost 1418.3353369521449 --- Hour 32 --- Hourly Cost 1465.2064164233996 --- Hour 33 --- Hourly Cost 1512.5827242326895 --- Hour 34 --- Hourly Cost 1560.4589289019073 --- Hour 35 --- Hourly Cost 1608.8298642621169 --- Hour 36 --- Hourly Cost 1657.6905210831587 --- Hour 37 --- Hourly Cost 1707.036039284886 --- Hour 38 --- Hourly Cost 1756.8617006790696 --- Hour 39 --- Hourly Cost 1807.1629221963822 --- Hour 40 --- Hourly Cost 1857.9352495575672 --- Hour 41 --- Hourly Cost 1909.1743513520025 --- Hour 42 --- Hourly Cost 1960.8760134905492 --- Hour 43 --- Hourly Cost 2013.0361340028617 --- Hour 44 --- Hourly Cost 2065.6507181520274 --- Hour 45 --- Hourly Cost 2118.71587384217 --- Hour 46 --- Hourly Cost 2172.227807296817 --- Hour 47 --- Hourly Cost 2226.1828189877015 --- Hour 48 --- Hourly Cost 2280.5772997958516 --- Hour 49 --- Hourly Cost 2335.407727388032 --- Hour 50 --- Hourly Cost 2390.6706627933236 --- Hour 51 --- Hourly Cost 2418.4710032765515 --- Hour 52 --- Hourly Cost 2418.4710032765515 --- Hour 53 --- Hourly Cost 2418.4710032765515 --- Hour 54 --- Hourly Cost 2418.4710032765515 --- Hour 55 --- Hourly Cost 2418.4710032765515 --- Hour 56 --- Hourly Cost 2418.4710032765515 --- Hour 57 --- Hourly Cost 2418.4710032765515 --- Hour 58 --- Hourly Cost 2418.4710032765515 --- Hour 59 --- Hourly Cost 2418.4710032765515 --- Hour 60 --- Hourly Cost 2418.4710032765515 --- Hour 61 --- Hourly Cost 2418.4710032765515 --- Hour 62 --- Hourly Cost 2418.4710032765515 --- Hour 63 --- Hourly Cost 2418.4710032765515 --- Hour 64 --- Hourly Cost 2418.4710032765515 --- Hour 65 --- Hourly Cost 2418.4710032765515 --- Hour 66 --- Hourly Cost 2418.4710032765515 --- Hour 67 --- Hourly Cost 2418.4710032765515 --- Hour 68 --- Hourly Cost 2418.4710032765515 --- Hour 69 --- Hourly Cost 2418.4710032765515 --- Hour 70 --- Hourly Cost 2418.4710032765515 --- Hour 71 --- Hourly Cost 2418.4710032765515 --- Hour 72 --- Hourly Cost 2418.4710032765515 --- Hour 73 --- Hourly Cost 2418.4710032765515 --- Hour 74 --- Hourly Cost 2418.4710032765515 --- Hour 75 --- Hourly Cost 2418.4710032765515 --- Hour 76 --- Hourly Cost 2418.4710032765515 --- Hour 77 --- Hourly Cost 2418.4710032765515 --- Hour 78 --- Hourly Cost 2418.4710032765515 --- Hour 79 --- Hourly Cost 2418.4710032765515 --- Hour 80 --- Hourly Cost 2418.4710032765515 --- Hour 81 --- Hourly Cost 2418.4710032765515 --- Hour 82 --- Hourly Cost 2418.4710032765515 --- Hour 83 --- Hourly Cost 2418.4710032765515 --- Hour 84 --- Hourly Cost 2418.4710032765515 --- Hour 85 --- Hourly Cost 2418.4710032765515 --- Hour 86 --- Hourly Cost 2418.4710032765515 --- Hour 87 --- Hourly Cost 2418.4710032765515 --- Hour 88 --- Hourly Cost 2418.4710032765515 --- Hour 89 --- Hourly Cost 2418.4710032765515 --- Hour 90 --- Hourly Cost 2418.4710032765515 --- Hour 91 --- Hourly Cost 2418.4710032765515 --- Hour 92 --- Hourly Cost 2418.4710032765515 --- Hour 93 --- Hourly Cost 2418.4710032765515 --- Hour 94 --- Hourly Cost 2418.4710032765515 --- Hour 95 --- Hourly Cost 2418.4710032765515 --- Hour 96 --- Hourly Cost 2418.4710032765515 --- Hour 97 --- Hourly Cost 2418.4710032765515 --- Hour 98 --- Hourly Cost 2418.4710032765515 --- Hour 99 --- Hourly Cost 2418.4710032765515 --- Hour 100 --- Hourly Cost 2418.4710032765515 --- Hour 101 --- Hourly Cost 2418.4710032765515 --- Hour 102 --- Hourly Cost 2418.4710032765515 --- Hour 103 --- Hourly Cost 2418.4710032765515 --- Hour 104 --- Hourly Cost 2418.4710032765515 --- Hour 105 --- Hourly Cost 2418.4710032765515 --- Hour 106 --- Hourly Cost 2418.4710032765515 --- Hour 107 --- Hourly Cost 2418.4710032765515 --- Hour 108 --- Hourly Cost 2418.4710032765515 --- Hour 109 --- Hourly Cost 2418.4710032765515 --- Hour 110 --- Hourly Cost 2418.4710032765515 --- Hour 111 --- Hourly Cost 2418.4710032765515 --- Hour 112 --- Hourly Cost 2418.4710032765515 --- Hour 113 --- Hourly Cost 2418.4710032765515 --- Hour 114 --- Hourly Cost 2418.4710032765515 --- Hour 115 --- Hourly Cost 2418.4710032765515 --- Hour 116 --- Hourly Cost 2418.4710032765515 --- Hour 117 --- Hourly Cost 2418.4710032765515 --- Hour 118 --- Hourly Cost 2418.4710032765515 --- Hour 119 --- Hourly Cost 2418.4710032765515 --- Hour 120 --- Hourly Cost 2418.4710032765515 --- Hour 121 --- Hourly Cost 2418.4710032765515 --- Hour 122 --- Hourly Cost 2418.4710032765515 --- Hour 123 --- Hourly Cost 2418.4710032765515 --- Hour 124 --- Hourly Cost 2418.4710032765515 --- Hour 125 --- Hourly Cost 2418.4710032765515 --- Hour 126 --- Hourly Cost 2418.4710032765515 --- Hour 127 --- Hourly Cost 2418.4710032765515 --- Hour 128 --- Hourly Cost 2418.4710032765515 --- Hour 129 --- Hourly Cost 2418.4710032765515 --- Hour 130 --- Hourly Cost 2418.4710032765515 --- Hour 131 --- Hourly Cost 2418.4710032765515 --- Hour 132 --- Hourly Cost 2418.4710032765515 --- Hour 133 --- Hourly Cost 2418.4710032765515 --- Hour 134 --- Hourly Cost 2418.4710032765515 --- Hour 135 --- Hourly Cost 2418.4710032765515 --- Hour 136 --- Hourly Cost 2418.4710032765515 --- Hour 137 --- Hourly Cost 2418.4710032765515 --- Hour 138 --- Hourly Cost 2418.4710032765515 --- Hour 139 --- Hourly Cost 2418.4710032765515 --- Hour 140 --- Hourly Cost 2418.4710032765515 --- Hour 141 --- Hourly Cost 2418.4710032765515 --- Hour 142 --- Hourly Cost 2418.4710032765515 --- Hour 143 --- Hourly Cost 2418.4710032765515 --- Hour 144 --- Hourly Cost 2418.4710032765515 --- Hour 145 --- Hourly Cost 2418.4710032765515 --- Hour 146 --- Hourly Cost 2418.4710032765515 --- Hour 147 --- Hourly Cost 2418.4710032765515 --- Hour 148 --- Hourly Cost 2418.4710032765515 --- Hour 149 --- Hourly Cost 2418.4710032765515 --- Hour 150 --- Hourly Cost 2418.4710032765515 --- Hour 151 --- Hourly Cost 2418.4710032765515 --- Hour 152 --- Hourly Cost 2418.4710032765515 --- Hour 153 --- Hourly Cost 2418.4710032765515 --- Hour 154 --- Hourly Cost 2418.4710032765515 --- Hour 155 --- Hourly Cost 2418.4710032765515 --- Hour 156 --- Hourly Cost 2418.4710032765515 --- Hour 157 --- Hourly Cost 2418.4710032765515 --- Hour 158 --- Hourly Cost 2418.4710032765515 --- Hour 159 --- Hourly Cost 2418.4710032765515 ---= Keep the equipment =--- Total operating Cost 324985.21754533396

Now that we've established the total cost of ownership, we can script replacing the tractor at a specific amount of workHours like so.
We also run an example of replacing the Fendt every 40 hours over 10 years

Code: Select all

def costOfOwnershipReplace(price, opHoursPerYear, replaceAtOpHour, yearsToRunSim):
    sumCost = 0
    operatingTime = 1
    age = 0
    for hours in range (1, yearsToRunSim*opHoursPerYear):
        #print("--- Hour ", hours, "---")
        if operatingTime >= replaceAtOpHour:
            replaceCost = price - sellValue(price, age, operatingTime*3600)
            #print("Replace cost ", replaceCost, " at age ", age, " and opHours ", operatingTime)
            sumCost = sumCost + replaceCost
            age = 0
            operatingTime = 1
        else:
            hourCost = repairCostOverTime(price, 480, (operatingTime-1)*3600, operatingTime*3600)
            #print("Hourly Cost ", hourCost)
            operatingTime = operatingTime + 1
            sumCost = sumCost + hourCost
            if (operatingTime % opHoursPerYear) == 0:
                age = age + 1
    #print("---= Replace the equipment =---")
    #print("Total operating Cost ", sumCost)
    return sumCost

costOfOwnershipReplace(329000,16,40,10)

	Code: Select all --- Hour 1 --- Hourly Cost 284.4907877464182 --- Hour 2 --- Hourly Cost 312.210424689934 --- Hour 3 --- Hourly Cost 340.77610086327354 --- Hour 4 --- Hourly Cost 370.16346281333176 --- Hour 5 --- Hourly Cost 400.3501468940273 --- Hour 6 --- Hourly Cost 431.3155221572384 --- Hour 7 --- Hourly Cost 463.0404774908134 --- Hour 8 --- Hourly Cost 495.5072436679148 --- Hour 9 --- Hourly Cost 528.6992432725746 --- Hour 10 --- Hourly Cost 562.6009631254026 --- Hour 11 --- Hourly Cost 597.1978450489814 --- Hour 12 --- Hourly Cost 632.4761917158634 --- Hour 13 --- Hourly Cost 668.423085002493 --- Hour 14 --- Hourly Cost 705.0263147908387 --- Hour 15 --- Hourly Cost 742.2743165590208 --- Hour 16 --- Hourly Cost 780.1561164132092 --- Hour 17 --- Hourly Cost 818.6612824573699 --- Hour 18 --- Hourly Cost 857.7798815910962 --- Hour 19 --- Hourly Cost 897.5024409804498 --- Hour 20 --- Hourly Cost 937.8199135713081 --- Hour 21 --- Hourly Cost 978.7236471156625 --- Hour 22 --- Hourly Cost 1020.2053562637218 --- Hour 23 --- Hourly Cost 1062.2570973423353 --- Hour 24 --- Hourly Cost 1104.8712454961305 --- Hour 25 --- Hourly Cost 1148.0404739141677 --- Hour 26 --- Hourly Cost 1191.7577349036646 --- Hour 27 --- Hourly Cost 1236.0162426048291 --- Hour 28 --- Hourly Cost 1280.8094571682661 --- Hour 29 --- Hourly Cost 1326.131070239554 --- Hour 30 --- Hourly Cost 1371.9749916153376 --- Hour 31 --- Hourly Cost 1418.3353369521449 --- Hour 32 --- Hourly Cost 1465.2064164233996 --- Hour 33 --- Hourly Cost 1512.5827242326895 --- Hour 34 --- Hourly Cost 1560.4589289019073 --- Hour 35 --- Hourly Cost 1608.8298642621169 --- Hour 36 --- Hourly Cost 1657.6905210831587 --- Hour 37 --- Hourly Cost 1707.036039284886 --- Hour 38 --- Hourly Cost 1756.8617006790696 --- Hour 39 --- Hourly Cost 1807.1629221963822 --- Hour 40 --- Replace cost 58781.333333333314 at age 2 and opHours 40 --- Hour 41 --- Hourly Cost 284.4907877464182 --- Hour 42 --- Hourly Cost 312.210424689934 --- Hour 43 --- Hourly Cost 340.77610086327354 --- Hour 44 --- Hourly Cost 370.16346281333176 --- Hour 45 --- Hourly Cost 400.3501468940273 --- Hour 46 --- Hourly Cost 431.3155221572384 --- Hour 47 --- Hourly Cost 463.0404774908134 --- Hour 48 --- Hourly Cost 495.5072436679148 --- Hour 49 --- Hourly Cost 528.6992432725746 --- Hour 50 --- Hourly Cost 562.6009631254026 --- Hour 51 --- Hourly Cost 597.1978450489814 --- Hour 52 --- Hourly Cost 632.4761917158634 --- Hour 53 --- Hourly Cost 668.423085002493 --- Hour 54 --- Hourly Cost 705.0263147908387 --- Hour 55 --- Hourly Cost 742.2743165590208 --- Hour 56 --- Hourly Cost 780.1561164132092 --- Hour 57 --- Hourly Cost 818.6612824573699 --- Hour 58 --- Hourly Cost 857.7798815910962 --- Hour 59 --- Hourly Cost 897.5024409804498 --- Hour 60 --- Hourly Cost 937.8199135713081 --- Hour 61 --- Hourly Cost 978.7236471156625 --- Hour 62 --- Hourly Cost 1020.2053562637218 --- Hour 63 --- Hourly Cost 1062.2570973423353 --- Hour 64 --- Hourly Cost 1104.8712454961305 --- Hour 65 --- Hourly Cost 1148.0404739141677 --- Hour 66 --- Hourly Cost 1191.7577349036646 --- Hour 67 --- Hourly Cost 1236.0162426048291 --- Hour 68 --- Hourly Cost 1280.8094571682661 --- Hour 69 --- Hourly Cost 1326.131070239554 --- Hour 70 --- Hourly Cost 1371.9749916153376 --- Hour 71 --- Hourly Cost 1418.3353369521449 --- Hour 72 --- Hourly Cost 1465.2064164233996 --- Hour 73 --- Hourly Cost 1512.5827242326895 --- Hour 74 --- Hourly Cost 1560.4589289019073 --- Hour 75 --- Hourly Cost 1608.8298642621169 --- Hour 76 --- Hourly Cost 1657.6905210831587 --- Hour 77 --- Hourly Cost 1707.036039284886 --- Hour 78 --- Hourly Cost 1756.8617006790696 --- Hour 79 --- Hourly Cost 1807.1629221963822 --- Hour 80 --- Replace cost 58781.333333333314 at age 2 and opHours 40 --- Hour 81 --- Hourly Cost 284.4907877464182 --- Hour 82 --- Hourly Cost 312.210424689934 --- Hour 83 --- Hourly Cost 340.77610086327354 --- Hour 84 --- Hourly Cost 370.16346281333176 --- Hour 85 --- Hourly Cost 400.3501468940273 --- Hour 86 --- Hourly Cost 431.3155221572384 --- Hour 87 --- Hourly Cost 463.0404774908134 --- Hour 88 --- Hourly Cost 495.5072436679148 --- Hour 89 --- Hourly Cost 528.6992432725746 --- Hour 90 --- Hourly Cost 562.6009631254026 --- Hour 91 --- Hourly Cost 597.1978450489814 --- Hour 92 --- Hourly Cost 632.4761917158634 --- Hour 93 --- Hourly Cost 668.423085002493 --- Hour 94 --- Hourly Cost 705.0263147908387 --- Hour 95 --- Hourly Cost 742.2743165590208 --- Hour 96 --- Hourly Cost 780.1561164132092 --- Hour 97 --- Hourly Cost 818.6612824573699 --- Hour 98 --- Hourly Cost 857.7798815910962 --- Hour 99 --- Hourly Cost 897.5024409804498 --- Hour 100 --- Hourly Cost 937.8199135713081 --- Hour 101 --- Hourly Cost 978.7236471156625 --- Hour 102 --- Hourly Cost 1020.2053562637218 --- Hour 103 --- Hourly Cost 1062.2570973423353 --- Hour 104 --- Hourly Cost 1104.8712454961305 --- Hour 105 --- Hourly Cost 1148.0404739141677 --- Hour 106 --- Hourly Cost 1191.7577349036646 --- Hour 107 --- Hourly Cost 1236.0162426048291 --- Hour 108 --- Hourly Cost 1280.8094571682661 --- Hour 109 --- Hourly Cost 1326.131070239554 --- Hour 110 --- Hourly Cost 1371.9749916153376 --- Hour 111 --- Hourly Cost 1418.3353369521449 --- Hour 112 --- Hourly Cost 1465.2064164233996 --- Hour 113 --- Hourly Cost 1512.5827242326895 --- Hour 114 --- Hourly Cost 1560.4589289019073 --- Hour 115 --- Hourly Cost 1608.8298642621169 --- Hour 116 --- Hourly Cost 1657.6905210831587 --- Hour 117 --- Hourly Cost 1707.036039284886 --- Hour 118 --- Hourly Cost 1756.8617006790696 --- Hour 119 --- Hourly Cost 1807.1629221963822 --- Hour 120 --- Replace cost 58781.333333333314 at age 2 and opHours 40 --- Hour 121 --- Hourly Cost 284.4907877464182 --- Hour 122 --- Hourly Cost 312.210424689934 --- Hour 123 --- Hourly Cost 340.77610086327354 --- Hour 124 --- Hourly Cost 370.16346281333176 --- Hour 125 --- Hourly Cost 400.3501468940273 --- Hour 126 --- Hourly Cost 431.3155221572384 --- Hour 127 --- Hourly Cost 463.0404774908134 --- Hour 128 --- Hourly Cost 495.5072436679148 --- Hour 129 --- Hourly Cost 528.6992432725746 --- Hour 130 --- Hourly Cost 562.6009631254026 --- Hour 131 --- Hourly Cost 597.1978450489814 --- Hour 132 --- Hourly Cost 632.4761917158634 --- Hour 133 --- Hourly Cost 668.423085002493 --- Hour 134 --- Hourly Cost 705.0263147908387 --- Hour 135 --- Hourly Cost 742.2743165590208 --- Hour 136 --- Hourly Cost 780.1561164132092 --- Hour 137 --- Hourly Cost 818.6612824573699 --- Hour 138 --- Hourly Cost 857.7798815910962 --- Hour 139 --- Hourly Cost 897.5024409804498 --- Hour 140 --- Hourly Cost 937.8199135713081 --- Hour 141 --- Hourly Cost 978.7236471156625 --- Hour 142 --- Hourly Cost 1020.2053562637218 --- Hour 143 --- Hourly Cost 1062.2570973423353 --- Hour 144 --- Hourly Cost 1104.8712454961305 --- Hour 145 --- Hourly Cost 1148.0404739141677 --- Hour 146 --- Hourly Cost 1191.7577349036646 --- Hour 147 --- Hourly Cost 1236.0162426048291 --- Hour 148 --- Hourly Cost 1280.8094571682661 --- Hour 149 --- Hourly Cost 1326.131070239554 --- Hour 150 --- Hourly Cost 1371.9749916153376 --- Hour 151 --- Hourly Cost 1418.3353369521449 --- Hour 152 --- Hourly Cost 1465.2064164233996 --- Hour 153 --- Hourly Cost 1512.5827242326895 --- Hour 154 --- Hourly Cost 1560.4589289019073 --- Hour 155 --- Hourly Cost 1608.8298642621169 --- Hour 156 --- Hourly Cost 1657.6905210831587 --- Hour 157 --- Hourly Cost 1707.036039284886 --- Hour 158 --- Hourly Cost 1756.8617006790696 --- Hour 159 --- Hourly Cost 1807.1629221963822 ---= Replace the equipment =--- Total operating Cost 328509.69412612385

As we can see, the replace cost is offset by the lower maintenance, up to the point that it makes sense to replace the tractor 3 times, albeit at a small loss.

Now we can combine the two scripts but first calculating the keep forever cost and search for the soonest time we can replace and have economic benefit.

Code: Select all

minCostToReplace = price*10
    minCostToReplaceHours = 0 
    costToKeep = costOfOwnershipKeep(price, opHoursPerYear, yearsToRunSim)
    for replaceHours in range (1, yearsToRunSim*opHoursPerYear):
        costToReplace = costOfOwnershipReplace(price, opHoursPerYear, replaceHours, yearsToRunSim)
        if costToReplace < costToKeep:
            print("Replace at ",  replaceHours, " op Hours")
            print("Operating cost to keep ", costToKeep)
            print("Operating cost to replace ", costToReplace)
            return
        else:
            if costToReplace < minCostToReplace:
                minCostToReplace = costToReplace
                minCostToReplaceHours = replaceHours
    print("Replacing not profitable")
    print("Operating cost to keep ", costToKeep)
    print("Min Operating cost to replace ", minCostToReplace, " each ", minCostToReplaceHours, " hours")

whenToReplace(329000,16,10)

Code: Select all

Replacing not profitable
Operating cost to keep  324985.21754533396
Min Operating cost to replace  328509.69412612385  each  40  hours

[george.earlslight]

Part 5. Summary

As it seems, your first reply to my question was correct but I had a good time trying to validate it.
Keeping equipment forever, but repairing as soon as possible is the most economic decision game wise.

And this is where Giants can do better.
First and foremost, adding damage while sitting on a tractor without even the engine on is just plain wrong.
Moreover, adding the same amount of damage, only dependent on work hours, ignoring the type and amount of effort, is also wrong.
Encouraging the player to repair their equipment so often is not realistic or fun.

With the introduction of seasonal cycles, it would make sense to allow the farm economy flow naturally.
Run maintenance every X hours of work or once a year. Do you need to run maintenance many times per year?
That would be a sign that you need more or bigger equipment.

Personally, I'd be interested to a maintenance themed DLC.
Maintenance is a very important part of any farm and as such I think the game would benefit out of it.
Remove the damage percentage, it doesn't translate to anything in real life.
Replace it with operating hours since last service.
Add effects relevant to the equipment, if it's not properly serviced.
Ruptured tyre, faulty hydraulics, turbo pipe disconnected, not starting for tractors.
Row not pushing seeds, hydraulics not lowering on seeders/planters.
Row tine fallen off on cultivator.
This would create an interesting system, where maintenance isn't just a function of time and cost on the player's mind.

Bellow the link to the calculation sheets and the full python script.

Code: Select all

https://docs.google.com/spreadsheets/d/1KyPVa1dgnLlYSG7xfbVcrGCKHRhVL5mz8P0u7xKiv_Q/edit?usp=sharing

	Code: Select all import math def damageRate(wearDuration, operatingTime): if operatingTime > (3600*50): operatingTime = 3600*50 return (0.35 / (wearDuration/60)) + (0.00289*(operatingTime/3600)) def damageDone(wearDuration, operatingTimeStart, operatingTimeEnd): totDamage = 0 simTime = operatingTimeStart while simTime < operatingTimeEnd: damage = damageRate(wearDuration, simTime) * (1/3600) totDamage = totDamage + damage simTime = simTime + 1 return totDamage def repairCost(price, damage): return (0.09 * pow(damage, 1.5) * price) def repairCostOverTime(price, wearDuration, operatingTimeStart, operatingTimeEnd): return (repairCost(price,damageDone(wearDuration, operatingTimeStart, operatingTimeEnd))) def sellValue(price, age, operatingTime): usedPrice = price * 0.88 if age > 7: ageDevaluation = 1.25-(0.125*math.log(age)) else: ageDevaluation = 1 useDevaluation = (1-(5/3000*operatingTime/3600)) return (usedPrice*ageDevaluation*useDevaluation) #assumes repair every hour def costOfOwnershipKeep(price, opHoursPerYear, yearsToRunSim): sumCost = 0 for hours in range (1, yearsToRunSim*opHoursPerYear): #print("--- Hour ", hours, "---") hourCost = repairCostOverTime(price, 480, (hours-1)*3600, hours*3600) #print("Hourly Cost ", hourCost) sumCost = sumCost + hourCost #print("---= Keep the equipment =---") #print("Total operating Cost ", sumCost) return sumCost def costOfOwnershipReplace(price, opHoursPerYear, replaceAtOpHour, yearsToRunSim): sumCost = 0 operatingTime = 1 age = 0 for hours in range (1, yearsToRunSim*opHoursPerYear): #print("--- Hour ", hours, "---") if operatingTime >= replaceAtOpHour: replaceCost = price - sellValue(price, age, operatingTime*3600) #print("Replace cost ", replaceCost, " at age ", age, " and opHours ", operatingTime) sumCost = sumCost + replaceCost age = 0 operatingTime = 1 else: hourCost = repairCostOverTime(price, 480, (operatingTime-1)*3600, operatingTime*3600) #print("Hourly Cost ", hourCost) operatingTime = operatingTime + 1 sumCost = sumCost + hourCost if (operatingTime % opHoursPerYear) == 0: age = age + 1 #print("---= Replace the equipment =---") #print("Total operating Cost ", sumCost) return sumCost def whenToReplace(price, opHoursPerYear, yearsToRunSim): minCostToReplace = price*10 minCostToReplaceHours = 0 costToKeep = costOfOwnershipKeep(price, opHoursPerYear, yearsToRunSim) for replaceHours in range (1, yearsToRunSim*opHoursPerYear): costToReplace = costOfOwnershipReplace(price, opHoursPerYear, replaceHours, yearsToRunSim) if costToReplace < costToKeep: print("Replace at ", replaceHours, " op Hours") print("Operating cost to keep ", costToKeep) print("Operating cost to replace ", costToReplace) return else: if costToReplace < minCostToReplace: minCostToReplace = costToReplace minCostToReplaceHours = replaceHours print("Replacing not profitable") print("Operating cost to keep ", costToKeep) print("Min Operating cost to replace ", minCostToReplace, " each ", minCostToReplaceHours, " hours") whenToReplace(329000,4,10)

[humbe]

Great finds And thanks for adding your finds. Will have to look at details once I get back home..

[paul_c]

Brilliant! So......ummm.......50 hours?

[humbe]

Brilliant! So......ummm.......50 hours?

Hehe.. Feel free to replace your gear after 50 hours but sounds to me the conclusion still stands. Cheaper the longer you keep the gear so you have to decide when the loss of buying new is small enough to work for you or you are just tired of your old stuff

[paul_c]

I will read and digest it but I don't think there is a clear answer - sure, you can carry on using the same equipment and if you replaced like-for-like new, then theoretically there is a point "x" hours its more cost effective to replace (which will also be a complex function of other things, such as work time/year and how often you can get it in for repair). But I like my idea of doing a half-step upgrade each time. Additionally, replacing a bit sooner gives the advantage of tweaks on the performance/power of a tractor, for example if you like a cab with a better view, or 4WS, or whatever.

The other option is to buy a tractor merely for those jobs where speed/fuel economy isn't so important - for example, transport, loading, ploughing, cultivating - and NEVER repair it, ever. Just let it degrade then just keep using it until its thousands of hours old. (Its a shame my most recent boss subscribed to this idea...)

My hunch is that repairs little and often are a good strategy until ~40 hours, then keep using it for 5-10 more hours, then get a replacement (half a step up) at that point. Then you build a useful and varied fleet, rather than simply like-for-like. Also, I will never sell a tractor, unless it becomes genuinely unused due to replacement(s) and work style.

[george.earlslight]

I'm guessing 40-50h would match most play styles.
You can always phase out older equipment and use them in odd jobs, while using newer/bigger to keep maintenance and work hours low.
That's the natural evolution of most farms.

Honestly I'm more interested in a maintenance revamp from Giants after finding out how the current system works.

[humbe]

As long as theres no point at where Im losing money by still using something, Ill probably decide on when to buy new based on when I have money to spare and when I need more power as I tire of low working width..