If no on was hurt and minimal damage? My guesstimate following a Court Martial conviction would be 3-5 in Leavenworth and a BCD. Doing something stupid like lighting off a Hi-Cap {The AFFF system} with planes on board likely the same. Without the planes? NJP. Setting off the General Alarm? That would get you NJP meaning likely either three days Bread and Water or a week or so brig time. Doing a deliberate malicious hazard that resulted in death or severe damage to the ship? You be a long time in Kansas and possibly death.
The main reason things don't happen like that is because you are never alone and sailors can't drink at sea except on rare occasions where they can have one maybe two beers if Liberty has been a long time or not practical.
The truth? You could endanger a ship many ways both innocent unintentional and deliberate to do harm and damage acts. INTENT carries a lot of weight in the punishment and it should. I know how to put a carrier {the conventional ones} D.I.W. and not go below the second deck to do it. Every Machinist Mate and most other Snipes plus fire fighters were taught it. Woe unto someone doing it as a stupid prank though. You were messing with a 1200 PSI system. It was a procedure to save the ship and lives. Thankfully I only heard of it possibly being used on time on our ship while I was on it and it was an emergency act.
I’ve worked a bit on 350 psi Hydraulic systems, and only a couple of times on the 1,500 psi systems. Doing what you are suggesting is certainly a very, very dangerous thing to do - both to the ship, as well as the sailor.
I honestly don’t know what scares me more, electricity or hydraulics. So, what do I do? I’m an engineer and work with both. Let’s just say that I have a HUGE amount of respect for those who work with Hydraulics.
You may search high and low; I doubt you’ll find a more safety conscious engineer in the Hydraulics area than me. I get shivers just thinking about that. Ewwww, nasty, nasty, nasty.