new ship speed formula

[Ichthyic]

OK, so rolling through the old reddit posts, I saw someone had long ago figured out what the formula is for overall speed given ship weight and engine power.

its:

speed [distance units / second] = ((EnginePowerModifier * power) + (2000 * BaseShipSpeed - weight) * gear * TurboSpeedMultiplier) / 2000

where EPM is a constant at 4.5, and BSS is a constant at 8.

which means that ship weights tend to entirely be overpowered by engine power, and you only get about 22% difference in speed between the heaviest and lightest ships with max engine power.

so, I was fiddling with the numbers to give a heavier (pun intended) influence of weight into the formula, and have come up with a scaling that gives weight about double the influence it does currently.

it requires two things:

changing the constants for EPM and BSS, and increasing the scale of ship weights.

both are easily modded.

if we change the EPM to 4, and the BSS to 10, and increase the weight scale of ships from 500 to 10000 instead of 300 to 5000, it pretty much exactly doubles the influence of weight on overall ship speed. also, as engines become more powerful, they tend to overwhelm the difference in speed between very large ships and very small ships, as it should.

set up like this, the bounds would look like:

ship with 1000 power engine:

500 weight ship at gear 2 = 23.5
10000 weight at gear 2 = 14

ship with 5000 power engine:

500 weight at gear 2 = 39.5
10000 wgt at gear 2 = 30

so, with the lightest ship, you get about 50% increase in speed going from 1000 power to 5000 power, but with the heaviest ship, you get a little over 100% increase in speed going from 1000 to 5000.

the overall ship maximum speeds stay pretty close to the original, but the influence of weight is now much more important, and even MORE important to get a big engine into a big ship.



so what do people think? are these good numbers? do they scale nicely? should I make a mod?

any other suggestions?

[Dimensional Traveler]

What is TurboSpeedMultiplier?

[Ichthyic]

1.75

it's what happens when you hit the turbo key (default "F").

doubles your rate of fuel consumption for 1.75 times speed increase, and a reasonable chance per tick that your engine will explode, causing damage (about 30 damage IIRC).

you can use a suppressor to keep your engine from exploding while using turbo, if your ship has an aft compartment slot.

[Dimensional Traveler]

The formula is easy enough to put into a spreadsheet, so I did. I haven't been playing Sunless Sea very long, just a couple of weeks, but the first thought I have is this could seriously impact the economics of fuel and supply. Especially when first starting out. What is your proposed weight for the starting ship (Ligeia-class Steamer)? I think your comparisons should start with that ship since it is the starting ship, when finances are the tightest. For the same reasons you also need to compare speeds at gear 1 since that would be the usual cruising speed to conserve fuel I believe. (I just found the fuel consumption formula in the wiki, will have to do some number crunching with that and speeds.)

I also get different speeds under your proposed changes:
ship with 1000 power engine:

500 weight ship at gear 2 = 23.5 - I get 21.5
10000 weight at gear 2 = 14 - I get 12

ship with 5000 power engine:

500 weight at gear 2 = 39.5 - I get 29.5
10000 weight at gear 2 = 30 - I get 20

For comparison, these are the speeds I get using the original values you posted.
1000 power engine
500 weight ship at gear 1 = 10
500 weight ship at gear 2 = 17.75
10000 weight ship at gear 1 = 5.25
10000 weight ship at gear 2 = 8.25

5000 power engine
500 weight ship at gear 1 = 19
500 weight ship gear 2 = 26.75
10000 weight ship at gear 1 = 14.25
10000 weight ship gear 2 = 17.25

Starting ship (Ligeia-class Steamer, 800 power engine, 1000 weight ship):
gear 1 = 9.3
gear 2 = 16.8

This could just be a missing set of parenthesis in the formula as you posted it. At any rate those are my initial thoughts, will try to remember to followup once I crunch fuel efficiencies.

[Dimensional Traveler]

Okay, having done some playing with a spreadsheet I feel very confident in saying I have no clue how I feel about your proposal. :) On the other hand I did make some interesting findings about fuel efficiency!

To start, here are the speeds I get from the speed formula you provided and fuel consumption rates I got from the official Wiki for Sunless Sea.[sunlesssea.gamepedia.com]

(((Engine Power*0.0005)*(1-Fuel Efficiency))*Gear Speed)+Light = Fuel drain/s(in %)
Gear Speed is 1 for half speed and 2 for full speed
Light is 0 if off, 1 if on. (this means that the ship's light use 1% of fuel every second, regardless of your speed)

All of the calculation results below are for the starting ship, a Ligeia-class Steamer weight 1,000, with the default engine, an Elderly Steeple-Engine power 800.

Speed in "distance units per second"
Ship Speed (1) 9.3
Ship Speed (2) 16.8
Ship Speed (Full) 28.05

Fuel consumption in %/second
Lights on Lights off
Gear 1 1.4 0.4
Gear 2 1.8 0.8

With those I figured out "distance units per unit of fuel"
Fuel Economy (distance units per unit of fuel)
Gear 1, lights off 2325
Gear 1, lights on 664.2857143
Gear 2, lights off 2100
Gear 2, lights on 933.3333333

Caveats:
1) I have no idea what a "distance unit" is or how it relates to distances between locations in the game.
2) Fuel consumption is in "Percent per Second" but I could not find in the Wiki what it is a percent OF. I am assuming it is a percent of 1 unit of fuel. I or someone would have to test to confirm that.

Observations:
Keeping the lights on burns a LOT of fuel. Even with a big engine on a small ship, in most combinations the lights burn more fuel than moving the ship.
With the lights off speed 2 is not much less efficient than speed 1 (a bit surprising to me).
Speed 2 with the lights off is about THREE TIMES more efficient than speed 1 with the lights on.
Speed 2 with the lights on is 50% more efficient than speed 1 with the lights on.

Just for fun, here are the results for a Lampad Cutter (wgt 300) with a Compulsion engine (power 3500):

Ship Speed (1) 15.725
Ship Speed (2) 23.575
Ship Speed (Full) 35.35

Fuel consumption in %/second
Lights on Lights off
Gear 1 2.75 1.75
Gear 2 4.5 3.5

Fuel Economy (distance units per unit of fuel)
Gear 1, lights off 898.5714286
Gear 1, lights on 571.8181818
Gear 2, lights off 673.5714286
Gear 2, lights on 523.8888889

Three and a half times the power pushing one-third the weight only gets you a bit under a 70% increase in speed. And a lot less fuel efficiency. Interesting. And the lights still burn a significant percentage of the fuel.

I don't know how these would compare to your proposed Mod because I would need to know the exact numbers you would change the ships' weights to, but a change of just the EPM and BSS as suggested without changing ship weights would result in ship speeds increasing by 5% to 20% and fuel efficiency by 5% to 25%, depending on the exact ship-engine combinations.

Tentative Conclusions:
If you need to conserve fuel, turn the lights out.
If you are running low on food, turn the lights out and speed up.

[Dimensional Traveler]

I think I scared Ichthyic away. :(

[Wlerin]

If you mouseover the fuel bar you'll see it gives the amount remaining as a percent, that's what fuel consumption is a percent of. Engine fuel consumption is Power/1000 at Gear 2, or Power/2000 at Gear 1. The light always consumes 1% of a barrel per second while on regardless of other concerns.

[Ichthyic]

yeah, sorry, didn't feel like arguing how to do maths.

my calculations are correct.

I'll post the scales I ended up using for ship weights tomorrow, but basically it was a rising scale where the heavier you started, the more got added, and that ends up in double the weight for the dreadnought.

I've played with every ship under this new balance, and it works just fine.

all it means is that you really need to focus on putting bigger engines in bigger ships now, which is what a lot of people were asking for once upon a time.

[Wlerin]

@Ichthyic You realise your original recommendation actually slows the large ships down, right?
From 15.5 - 33.5 with the old weights and constants, to 14 - 30 with the new ones (ignoring the starter engines). It was actually ever so slightly more beneficial under the original values to buy a bigger engine for a bigger ship. (2.16x~ vs. 2.14x~)

Didn't bother checking the smaller weight classes.

[Dimensional Traveler]

Originally posted by Ichthyic:

yeah, sorry, didn't feel like arguing how to do maths.

my calculations are correct.

I'll post the scales I ended up using for ship weights tomorrow, but basically it was a rising scale where the heavier you started, the more got added, and that ends up in double the weight for the dreadnought.

I've played with every ship under this new balance, and it works just fine.

all it means is that you really need to focus on putting bigger engines in bigger ships now, which is what a lot of people were asking for once upon a time.

Ichthyic, I wasn't trying to "argue how to do maths" with you. Even if I wanted to I couldn't because I don't know your proposed new ship weights.

You asked for opinions and input on your proposed Mod. It seems to me that it is likely to impact the need for and ability to buy sufficient fuel and supplies in the game, especially early in the game. So I wanted to find some way to compare the base game against your proposed changes. In the process I also discovered some (IMO) neat info that helps me play better. For that I thank you for providing and pointing to where the equations are.

I hope you will post your new ship weights to go with your Mod. I'm the kind of person who likes playing with numbers and I would like to explore the effects of your proposal.

I also intend to upload the spreadsheet I made for this so other players can use it. Maybe it will even help you or provide a leaping off point for something new from you. (Maybe not, its entirely up to you.) In any event I was not trying to discourage you or put you down. I just wanted to participate and help. I'm sorry if you feel otherwise.

[Wlerin]

Originally posted by Ichthyic:

OK, so rolling through the old reddit posts, I saw someone had long ago figured out what the formula is for overall speed given ship weight and engine power.

its:

speed [distance units / second] = ((EnginePowerModifier * power) + (2000 * BaseShipSpeed - weight) * gear * TurboSpeedMultiplier) / 2000

fwiw the reason Dimensional Traveller was getting his calculations wrong is because the formula you posted is incorrect. Presumably you added extra parentheses to try and make it clearer when posting, but the final closing parenthesis comes too late.

This is the correct formula, though only the outermost parentheses are actually necessary (and those are the only ones in the reddit version):

speed [distance units / second] = ((EnginePowerModifier * power) + (2000 * BaseShipSpeed - weight)) * gear * TurboSpeedMultiplier / 2000

[Dimensional Traveler]

*bleep* I thought I copied it correctly. Thanks for the correction. A link to the corrected spreadsheet can be viewed here:
https://docs.google.com/spreadsheets/d/1OiX0QsTK4-TzGunt9xedzD3Q3lDNEieI4Rr53iRP1S4/edit?usp=sharing

[Dimensional Traveler]

For Ichthyic and any others interested I have added another tab to the spreadsheet to allow side-by-side comparisons of different ship/engine combinations and/or comparing the effects of modifying the game constants (Engine Power Modifier, Base Ship Speed and Turbo Speed Modifier). Permissions should allow anyone to download a copy of it if they wish.