Ship speed and fuel consumption tables

[Dimensional Traveler]

After participating in a thread about a possible Mod to ship weights and engine power to increase the need for bigger engines in bigger ships I created a spreadsheet to calculate ship's speed and fuel economy. A copy is available on Google Docs at the link at the bottom of this post. Since I don't know how long a "distance unit" is on the Sunless Sea map I would suggest only using these for comparisons between ship/engine combinations. (I would just make this a Guide but I bought the game elsewhere, not from Steam so they won't allow that.) I would also like to thank Ichthyic for making me aware of where these formulas could be found.

Ship's speed is calculated by a formula from Reddit. The URL is below:
speed [distance units / second] = (EnginePowerModifier * power + 2000 * BaseShipSpeed - weight) * gear * TurboSpeedMultiplier / 2000
where EnginePowerModifier is a constant at 4.5, and BaseShipSpeed is a constant at 8.
TurboSpeedMultiplier = 1.75 ("F" button)
https://www.reddit.com/r/sunlesssea/comments/5yyhbg/ship_speed_formula/

Fuel Consumption is calculated using a formula from the official Wiki for Sunless Sea. Again the URL is below:
(((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)
https://sunlesssea.gamepedia.com/Fuel#Usage

Once you know how far you will go in a second and how much fuel that takes, it is easy to calculate how far you can go with 1 unit (barrel) of fuel. These numbers are rounded to the nearest whole number for formatting purposes.
(Speed * 100) / Consumption

The spreadsheet can be viewed here:
https://docs.google.com/spreadsheets/d/1OiX0QsTK4-TzGunt9xedzD3Q3lDNEieI4Rr53iRP1S4/edit?usp=sharing

[Wlerin]

Your parentheses are wrong. 800 Power & 1000 Weight gives 9.3 and 18.6 speed at 1 and 2 respectively.

Also use Google Sheets[sheets.google.com] instead of this unreadable mess.

[Dimensional Traveler]

Originally posted by Wlerin:

Your parentheses are wrong. 800 Power & 1000 Weight gives 9.3 and 18.6 speed at 1 and 2 respectively.

Also use Google Sheets[sheets.google.com] instead of this unreadable mess.

Thanks for the formula correction. Sorry you found the tables difficult to read, now you can see the spreadsheet for yourself.

[Dimensional Traveler]

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.

[desolation0]

So quick basic takeaways if I'm reading it right.

1. Practically always at least second gear. At no extra cost in fuel efficiency for propulsion you'll reduce either your terror per distance or the cost of running the lights per distance.

2. If running your lights constantly and can't explode, always full speed. The savings in lighting makes up for the cost in propulsion compared to second gear. The only exception seems to be the Compulsion engine which very slightly favors second gear. That seems to be close enough that fear costs, which do still go up with a light, still tip towards maintaining full speed constantly.

3. Lights out probably means second gear for absolute efficiency. This would come down to your expense for removing fear per distance of course. The faster your ship and engine, the less fear you accumulate over a given distance. This is most useful to note if you have fear points to spare, but absolutely must stretch your fuel to the next port.

[Wlerin]

One more problem with the table:
Full Power negates Fuel Efficiency
https://docs.google.com/spreadsheets/d/1BM7Yh2qjn_lu4kKvsX_3lBfyab_cJk-25zcq7Tg3DP4

Use either the Avid Suppressor or the Fulgent Impeller, not both (unless you want to be prepared for emergency getaways I guess).

[Dimensional Traveler]

I appreciate the help in fixing problems with this, Wlerin.

Originally posted by Wlerin:

One more problem with the table:
Full Power negates Fuel Efficiency
https://docs.google.com/spreadsheets/d/1BM7Yh2qjn_lu4kKvsX_3lBfyab_cJk-25zcq7Tg3DP4

How do you know? Not necessarily disagreeing, just wondering how you know that. (Plus its annoying when reality refuses to conform to your mathematical model of it.)

Use either the Avid Suppressor or the Fulgent Impeller, not both (unless you want to be prepared for emergency getaways I guess).

Just because using both would use more fuel than it is possible to carry running at full power constantly? :) (Wait, did we just invent a Victorian warp drive? Is the Dawn Machine powered by exploding Full Power Fulgent Impellers?! Is that my imagination I see disappearing over the horizon?)

I realized there is another problem with the Full Power mileage. It assumes that you engage Full Power instantly every time you start burning another unit of fuel. Difficult if it is even possible. Any delay at all in clicking on the button/hitting the F key costs fuel efficiency. Personally I don't think I'll even try and will just cruise around at gear 2 full speed.

(Now I'm thinking about removing those Full Power rows entirely. They just may be open mirrorboxes of dream snakes.)

[Iconian]

@Dimensional Traveler: I created a guide last year that may prove useful for some of the information you're talking about: https://steamcommunity.com/sharedfiles/filedetails/?id=1397427536&searchtext=Search+Sunless+Sea+Guides

[Dimensional Traveler]

Originally posted by Iconian:

@Dimensional Traveler: I created a guide last year that may prove useful for some of the information you're talking about: https://steamcommunity.com/sharedfiles/filedetails/?id=1397427536&searchtext=Search+Sunless+Sea+Guides

Thanks, I did read it before I started on my spreadsheet but it didn't really provide the information I was looking for.

[Wlerin]

Originally posted by Dimensional Traveler:

Originally posted by Wlerin:

One more problem with the table:
Full Power negates Fuel Efficiency
https://docs.google.com/spreadsheets/d/1BM7Yh2qjn_lu4kKvsX_3lBfyab_cJk-25zcq7Tg3DP4

How do you know? Not necessarily disagreeing, just wondering how you know that.

By testing it in game. It's very obvious if you're using the Fulgent Impeller.

[Dimensional Traveler]

Originally posted by Wlerin:

Originally posted by Dimensional Traveler:

How do you know? Not necessarily disagreeing, just wondering how you know that.

By testing it in game. It's very obvious if you're using the Fulgent Impeller.

Okay, thanks. I'll modify the spreadsheet when I have more time, probably this weekend.

[Kyun]

From the code, fuel power and efficiency both work together ; efficiency is accounted for first, then the turbo doubles the fuel usage - NavigationConstants.TurboFuelCostMultiplier = 2 by default. Light is indeed not affected.

RecalculateFuel() :
...

float num = (!(Boat.TargetSpeed < 0f)) ? (Boat.TargetSpeed / Boat.SpeedIncrementUnit) : (0f - Boat.TargetSpeed / Boat.SpeedIncrementUnit);
float num2 = num * GameProvider.Instance.NavigationConstants.EngineFuelDecrementUnit * (float)Boat.EnginePower;
if (Boat.FuelEfficiency > 0)
{
	num2 -= num2 * ((float)Boat.FuelEfficiency / 100f);
}
Boat.PercentageThroughFuelBarrel -= num2 * Boat.TurboMultiplier * (Boat.Turboing ? GameProvider.Instance.NavigationConstants.TurboFuelCostMultiplier : 1f);
if (Boat.Headlight == HeadlightPower.FullPower)
{
	Boat.PercentageThroughFuelBarrel -= GameProvider.Instance.NavigationConstants.LightFuelDecrementUnit;
}

...

[Wlerin]

So I tested it again, and the results were... interesting. I was losing 2-3% of a barrel per tick observed (2.25% calculated, due to Tireless Mechanic + Fulgent Impeller) at Gear 2. If Efficiency is included, one would expect to lose 4-6% (4.5%) per tick at Full Power. If it is not included, one would expect 10% per tick at Full Power.

Observed was 7-8%.


What is Boat.TurboMultiplier?

[Kyun]

Boat.TurboMultiplier seems to be related to engines overheating (turbo boost and fuel usage) :

if (TargetEngineTemperature > 200f && !Turboing)
{
	Turboing = true;
	TurboMultiplier = GameProvider.Instance.NavigationConstants.TurboSpeedMultiplier;
	...
}
if (TargetEngineTemperature <= 200f && Turboing)
{
	Turboing = false;
	TurboMultiplier = DEFAULT_TURBO_SPEED;
	...
}

DEFAULT_TURBO_SPEED = 1 I think

[Wlerin]

Second condition turns Turbo off if your engine cools down far enough. TurboSpeedMultiplier should be 1.75, so when Turbo is active (and the engine is still hot) TurboMultiplier is also 1.75.

Which... explains the numbers I observed above (2.25%*1.75*2==7.875%), but that should affect every other engine too?

[Kyun]

Plots for each ship : https://ibb.co/PG4Cwx8

Speed (vanderbights / minutes) is blue, efficiency (venderbights / 1K creds) is green.
Turbo data points are triangles with dashed lines while non turbo data points are squares.
The lightgreen lines mean the ship light is on. Your efficiency lies in the shaded area between the dark (always light off) and light green (always light on) according to the frequency of light you are using.

You need to take into account the fuel and the rations used by the crew, which I did. Fuel cost = 10, supply = 20.

Short version :
For all ships, turbo boosting with the smallest engine is always better than anything else until you get the last engine ; the efficiency is decreasing until then, turbo or not. You trade speed for a lot of money.

It is even worse to use turbo with intermediate engines for all ships. The efficiency loss when turboing with the smallest engine is smaller and smaller as ship weight increases, and turns into an efficiency gain for bigger ships (2000+ weight) since rations becomes more of an issue than fuel.

Starting at 3000 weight and 18 crew, you start using more rations than fuel, and increasing the engine power is good if you DO NOT turbo at all as efficiency starts to increase. Sadly, the smallest engine with turbo is still better at both speed AND efficiency (the green triangles are above the squares ones with engine power 800 and 2000+ weight).

For the best ship and a crew of 28, the last engine offers almost the same efficiency with and without using turbo. So use the avid suppressor and go turbo.

The last engine is the best for all ships above 500 weight (both speed and efficiency, turbo or not).

TD/DR :
Use the smallest engine + supressor unless you never turbo and your ship has 3000 or more weight.
Then use the last engine with or without the supressor, the efficiencies are equivalent.
With the supressor you'd be faster but the fuel used costs the same than the supplies used without the supressor and not turboing. It's a trade off between speed and a free utility slot.

Note : using the light is less of a loss with turbo rather than without (green area is smaller for turbo). It makes the game a little easier if you can afford to use the light whenever you want.

The last engine very high speed means you won't get a lot of events when docking to ports along the way.

From this, don't use claymen until you get the last engine unless you do not turbo and have 3000+ weight.