Submarine faster underwater?

[Galliumsphinx]

For the past 100 hours of gameplay, Ive been building and testing a Uboat, it has a top speed of 9.5m/s on the surface but 15.5m/s submerged. Physics states that the increased drag underwater should reduce my top speed. Any idea whats going on with my vehicle?

[Trench-foot]

It may be that air has a higher resistance than water, might want to run an experiment on that.

[BRRRT]

no somethings definetly wrong, maybe your surface engines are less powerful then the electric engines?

[XLjedi]

If you notice the speed differential with electric motors both on surface and underwater...

Couple other things come to mind:

Maybe not having to fight wave action on surface, and possibly an efficiency gain for the prop being full submerged. Once below a certain depth maybe the game engine doesn't penalize for running the prop too shallow.

[Drepface]

stormworks is weird like that. From experience, hydroplane style boats go the fastest with a given engine setup, followed by subs and then "normal" boats

[GrumpyOldMan]

Originally posted by Drepface:

stormworks is weird like that. From experience, hydroplane style boats go the fastest with a given engine setup, followed by subs and then "normal" boats

From what I can tell water physics are pretty sophisticated, ships have to work against waves, and a marginally submerged submarine beneath huge waves will get rocked around by the wave current unless you're submerging to greater depth.
Too bad the devs don't give any more insight since I'm sure more people are interested in the workings behind the curtain (similar to how factorio folks are doing it).

[Jerro]

Could just be the propellers not being fully submerged when it's surfaced.

[GrumpyOldMan]

Originally posted by jerrj:

Could just be the propellers not being fully submerged when it's surfaced.

As far as I know partial submerged propellers aren't a thing in Stormworks.

[Ra-Ra-Rasputin]

The water's surface has higher resistance because of things like wake robbing energy away from the boat. A real sub is amusingly slowed down by a couple of knots simply because the periscope is up, and it's not so because the periscope is a fragile instrument that demands it to slow down.

That being said, the game does simulate this difference a little too eagerly, to the degree that having a boat underwater has very very little resistance.

For grumpy old man, partially submerged props are definitely a thing. They have less resistance meaning they run at much higher RPS, but they also provide far less thrust. This is easy to test with the big props

[Galliumsphinx]

The problem is not with my motor setup or the props being only partly submerged when on the surface. I tested the speed using a snorkel so that the propulsion method is a constant variable during calm weather. The props are about three meters underwater when on the surface. The boat only picks up speed once hull is fully submerged. The periscope and snorkel both can be raised without affecting the phenomenon.

[XLjedi]

FWIW, modern subs are faster submerged... your VIIC is a bit of an anachronism in this game. They didn't make 30 knots submerged, and were faster on the surface.

The game engine is probably not THAT sophisticated to be able to detect an efficient teardrop shape vs. an old Uboat.

I guess if I had to error in one direction or the other, I'd go with faster submerged and not worry too much about what happens if someone builds a paddle-boat from the early 1900's that can do 50 knots.