And here is my attempt at a twin-cylinder steam engine. I had trouble wiring the extra cylinders in to make the timing of the rods right (1-2-3-4).
https://steamcommunity.com/sharedfiles/filedetails/?id=3365923819

Here's the upgraded paddle boat:
https://steamcommunity.com/sharedfiles/filedetails/?id=3365899695

Yes, it works fine. I rebuilt the paddle boat to use two of your Jupiter-style engines for each individual paddle wheel - since the bigger the paddle wheel, the harder it is to spin them at top revs, even with the Johnson bar at near-neutral. In addition, using giant wheels as floats helped reduce water resistance.
Only thing is that when trying to add multiple cylinders, the valve gear got stuck, and wouldn't move the way I wanted it. I may have timed it wrong. I have a prototype. I'll send the rebuilt paddle boat and the multi-cylinder engine attempt for you to check out. Thank you for your help!

I have looked at your creation, and it works perfectly for me. Could you maybe see if it also does indeed work for you? First put the Johnson bar in the forward most position by hitting the orange button 6 times, then adding throttle by repeatedly hitting the orange button on the regulator. The creation works best when the johnson bar is all the way forward

This is the Marine Parts mod by DR3K
https://steamcommunity.com/sharedfiles/filedetails/?id=2826571135&searchtext=marine+parts

So far it's just the Legend Mod extended, the modpack, X's train Mod, Fant mod and DR3K's marine parts. Any others were the same ones used for your Jupiter Locomotive. The Paddle Wheels are from DR3K's marine parts mod. Much more efficient than the Fant mod Paddles

I tried to spawn the vehicle, but I can't because I seem to miss a mod or more, do you know which ones?

Update: I've also tried to add multiple cylinders (minimum of 2 with the same valve gear, but it's not working right - it moves back-and-forth, and when I move the johnson bar either way, the engine just stalls/does not move. The second set of cylinders is set up exactly like the first on both sides. Could something wrong with the timing or wiring of the pistons? I will send you the prototype file soon. Please let me know what can be done. Thank you for your help.

Thank You!

I'll have a look at it soon, in the mean time, I did create a river paddle steamboat a while ago that does use piston power for rotating the paddle, but without any valvegear. Its movement is powered by thrusters. You can try it if you need some further inspiration: https://steamcommunity.com/sharedfiles/filedetails/?id=3362934424

Here is the link:
https://steamcommunity.com/sharedfiles/filedetails/?id=3362928655

Hello, lumgaming! Sorry to bother you again, but I was having trouble figuring out how to increase the top speed of the pistons in the steam engine setup/the Jupiter you built. I've already created a prototype of a paddle boat, but it's not nearly fast enough. My target speed is 25kph, maybe more. I've tried using fant's mod and DR3K's marine parts mod, which both work, but it's still slow. I'll send you a link of the prototype to try it out and see what you think. Let me know if any changes need to be done

Thank You! Keep making awesome creations!

I'd say have a module for each piston / valve gear set or delete the parts off of the module for one side so that it works for a single piston and single valve gear rod, then connect them together with the regulator and johnson bar connected to each module. Good luck with your build!

The only last problem I'm Having is when I used X's train mod for the rods - in the same setup way as the Jupiter - the valve gear moved the wheels back and forth, but didn't move at all when the Johnson bar was moved - either forward or back. How can I alleviate that?
Update: I had to reverse the direction of the bearings. LOL.

The only thing I have to ask last is how can I connect mutiple rods and cylinders/valve gears together to create a multi-cylinder/triple expansion steam engine?

Update: I did use one of the tick buttons wired into the counter. It worked exactly as described!
I'm a little rusty with building a Stephenson-type valve gear, though (which is normally used in marine steam engines, such as the Titanic). Do you have an example or do you know of any creation that would be close to being compatible with your engine control unit? Thank you so much for your help and patience, I'm kind of a newbie/enjoyer of creations rather than a builder.
BTW, you have yourself a follower! Great creations!

You could also connect a normal (not 1 tick) button to the multiplier, set the other number going into the multiplier to a low number, say 0.1, and have it constantly add its value to the counter, which means the johnson bar moves smoothly, though it would be nearly impossible to set it to 0 unless you use the white reset button

The sensor can be any distance as long as the in the description specified counters are set to that distance, though nothing can be in between the sensor and the target. The johnson bar works by having the buttons connected to a math block that multiplies the button from 1 to 15, which then outputs it into the main counter. This counter sets the position of the valve gear. A black button is -1, an orange one is 1 and a white one resets said counter. So when you press the move forward button it sends out a signal of 1, gets multiplied to 15 and that is added to the counter. The black button subtracts 15 and the white one resets it to 0, the neutral position. Hope this helps.

Not only that, how did you integrate a neutral position/reset switch for the Johnson bar? That would be great for a steam ship to make an immediate stop of the engines!

Oh OK, thank you! Yeah, the problem I was trying to solve was I wanted to build a realistic control system of valves and for the steam engine - which I would later control through an EOT (Engine Order Telegraph) I made. I still need to figure out how to resize the interior light that the legend mod has, though. Then the EOT will be complete. By the way, is there a certain distance or specification for the smart sensor to be away from the driving rods of the engine?

It basically takes the current position of the valve gear by its distance to a sensor, which then calculates the force applied to the piston proportionally to this distance. It also has a sensor on the piston position so that it knows when to flip the direction of power on it. The valve gear works by literally rotating the position on the axle by a ceirtain amount instead of the normal more complicated mechanical system, because I find this to be a lot less laggy and smoother.

It has been a while since I last played the game, but I did find in my blueprints a logic circuit block that I used on my 2-6-0 that should hopefully help with your project:
https://steamcommunity.com/sharedfiles/filedetails/?id=3360779117

Great replica of the Jupiter! By the way, can you make a tutorial on how to set up this logic? I've been trying to create a marine steam engine with Stephenson Valve gear, and have tried to reverse-engineer the valve gear from different locomotives - but haven't had any success.