Okay sorry this took so long my brother's house cough on fire. So all you need to do is take the fuselage attached to the piston and add couple more zeros on buoyancy. Then put a VTOL engine and put it into the buoyant fuselage block. Have the nozzles at the rear of boat where the prop is and have it to where you turn and the nozzles move.(change the input) you can also try shrinking down the buoyant fuselage block

@MASTERMEMES now see

@Aarav ok post it then

@MASTERMEMES I'll post anyway. Tell me if you need help

Tell me if you need me to do this so i download it.

I never made a sub. But I have an idea. Put a piston with a fuselage on it . Make sure that they are in the COM . Then with the xml mode make the fuselage very floaty . Finally make the scale of them very very smale .make sure the piston is controlled with trim or vtol . And for make it float make the minimal range of the piston -1 or -2. That depends on how big is your sub. If you didn't now how to do this things just give it to me and I will do it for you trust me.

@Aarav that's ok I just want know how to fix the bouyant so it can supmerged and surface without bouncing. Btw thanks :)

I've made your variant ! Average speed is 35mph , and do you want it floating , I covered the cockpit for you , and do you want something else ? Tell me and if not I'll submit it

Well I will get it to you in the morning. Hopefully. 😉

@Planeacceleration oh ok.. well it's night here (West Indonesian time)

I'll take a look at it this evening,(usa time) I have work this morning.

Love the shape

@Planeacceleration

@FatEgg