I've decided to make a guide on how I've made submarines, with the intention of giving some people the knowledge to make their own subs. This is a style that ditches the common use of pistons and xml modded fuselages in favor of building a sub which (though lacking in ballast control) is able to maneuver freely through the water as a submarine does. Note that this style of building was inspired by this submarine

1)Get the Underwater Camera Mod or Ocean Mod. I recommend Ocean mod if you can run it.

2)Get the FineTuner Mod

3)Get the Overload Mod (unless you prefer xml modding the old fashioned way)

4)Build the body of your submarine. When building a replica do NOT worry about the size right at this stage, just focus on getting the shape and overall proportions correct.

5)Assuming you're making a replica, and you made proportions correct, open this website
-)Then access the submarine's Wikipedia article so you can gain the length of the real sub. Use the button in the designer with the 'i' in it to find your craft's length.

6)Go to the website, use the '_ is what percent of __' part of it. Put the REAL sub's value into the first (left) blank, and your creation's value into the second (right) blank.
-)Click Calculate, copy the answer and move the decimal point two numbers to the left.
-)Access the scale tool in the FineTuner interface, Uncheck 'scale only selected parts' and paste your modified value into the all the Width, Height, and Length values.

(Example: Skipjack sub length: 251.7 ft, SP craft length: 51.2 ft.

Percentage Calculator
251.7 is what percent of 51.2 Calculate: 491.6015624999999
491.6015624999999 >>> 4.916015624999999

VV Finetuner>Scale>uncheck (scale only selected parts) VV
Width:4.916015624999999
Height:4.916015624999999
Length 4.916015624999999

Click Scale

Your sub should now be merely a foot off from the actual length if that.

7)Once you've gotten the size of your sub down (which will be big if you're making a replica that's not a midget sub) the next thing you need to do is add buoyancy. Use two fuselage parts and put them inside your sub. Nudge them in a manner so they will keep the sub level.

8)Add a Gyroscrope, adjust its values to help keep your sub level. As an alternative you can also utilize buoyancy and weight blocks to create a more natural stabilization. (Guide coming soon)

9) Use this engine or an engine like it and add it to your sub. Though the engine from my inspiration submarine works it's got a MUCH higher part count and isn't as easy to modify. Adjust the length of the propeller blades (through xml if necessary) to boost the engine's power.

10)Add the control surfaces, use structural wings and put them on rotators. Use Overload, add in and adjust damperMultiplier to the Rotator part of the Overload menu. Adjust it with big but simple numbers (100, 1000, 10000) till the rotators don't wobble anymore. Don't put it too high, or the rotators will be slow.

11)Adjust the structural wings to proper shape, then increase the width, and ONLY the width. Set the width to a very high value, then use overload to scale down the width. There's a unique exploit in SP which allows wings to keep their lift even when they are scaled down to a smaller size.

Though it will make your sub rather good at gliding in the air, it will be necessary to ensure responsive controls underwater.

12)Put a VERY large vertical structural wing inside the submarine to keep it moving straight. Putting a horizontal wing of similar size would be advised as well, as it can help endure effective depth control with the orientation of pitch (i.e. preventing the sub from moving forward while the nose is down).

13)Use Overload/xml modding to adjust the buoyancy of the fuselage pieces. Play with the numbers with the goal of getting as close to making your sub neutral in buoyancy (not quite float yet not quite sink) as possible. I suggest doing this after getting the engine and control surfaces working so you can better get a feel for if the buoyancy is properly neutral enough for underwater maneuvering.

14)The final step will be to add fine-tuned adjustments, adjusting the width of control surfaces, drag, size of the engine propellers, buoyancy, and more in order to get the submarine just right, especially if you're building a replica.

Assuming you've done everything just right (and I've explained it well enough) then these should be the steps to ensure you make a functioning submarine! I hope this guide can inspire some others to build, especially those more proficient in building than I!

Final notes

-) It is recommended that you not let your sub exceed 1 million pounds in weight to ensure responsive controls