Unfortunately, there's not much that can be done to prevent a hull from being penetrated by a round that can also penetrate body armor.
Body armor is specifically designed to catch a bullet and slow it down over a distance, which is why the shot still leaves a bruise or broken bones (in some cases).
Even having a steel hull that's 3/4" thick steel isn't a guarantee that it's bullet proof. The .50 cal rounds in the video below aren't armor piercing, yet they very nearly penetrate the steel plate. That's a gigantic amount of mass to have in a spaceship and would take a massive amount of fuel to propel it, as well as try to get it to change direction for "evasive maneuvers". You need Star Trek level tech to make that happen, essentially greatly reducing the momentum caused by the mass and Newton's laws of motion.
And a .50 cal handgun can easily penetrate multiple thinner steel car doors, with the glass and the interior still installed, but it's caught by a Kevlar vest. As this is done by a civilian, it's also not an armor piercing round, which is proven by it not going through the vest.
In the US Army Basic Training I had 23 years ago, we were shown the capabilities of a M16A2 armor piercing round before we were given the rifles to practice with. The relevant example here is that a steel ammo box was filled with water and shot. Neither the 2 sides of the box or the water significantly slowed down the 5.56mm round. For comparison, 5.56mm is a similar caliber to a .22 rifle, just with a much higher muzzle velocity and different shape. I wrote more about that here.
And yes, water can have an effect on bullets, just not the amount in an ammo can. And the higher the velocity the faster the bullet fragments in water, however this wasn't tested with armor piercing bullets.
And if you want to see what a .50 cal armor piercing (AP) round will do, here's another video. Apparently this guy isn't in the US. This is still considered an easily carried weapon for the battlefield, so could easily be used on a ship during boarding. It's also the same caliber as the .50 Desert Eagle of the handgun in a video above, so well within the realm of battle use, but it won't have the same stopping power due to the shorter barrel.
If you think changing the medium of the gun will make a difference, steel is more dense than body armor, so it wouldn't as easily be vaporized with a laser or plasma gun, but then you have surface finishes to deal with.
I wrote another Answer about lasers from my experience with laser cutters in non-professional manufacturing, and even included a video I made testing my theories about lasers and anti-laser armor.
Some of that Answer would also apply to plasma, but you're still dealing with something that is considerably hotter than the melting temp of most materials, so would easily penetrate steel just like body armor. The reason why a plasma cutter or laser cutter works on steel is because it is so much hotter than the melting point that it instantly vaporizes the material in front of it, rather than heating the whole piece.
You might be able to get away with plasma or lasers, due to the body armor being relatively thin, but you'd still need thick hulls, which would still have literally tons of mass. If you go with aluminum, which is more reflective and lighter than steel and would help prevent laser holes, it wouldn't work against plasma or slugs.
If you upgrade your hull with force fields, you might be onto something, but that would take a considerable amount of power, which might be better used to get away from your attacker. And that would probably have prevented your ship from an enemy breach, or at least boarding, anyway.
Also, if you have that level tech to be able to have it everywhere on the inside of your ship, you might be using it for body armor as well. There's this long standing race between armor and things to penetrate armor, with the piercing elements always getting the upper hand faster than the armor can change to protect it's wearer.
I can't find any article that specifically says it ATM, but in the race between protecting the wearer and killing an enemy, killing the enemy always wins in the end. Nothing is bullet proof, only bullet resistant. Your force field is turned down low to preserve power, so it'll take a 9mm, but not a .45 cal. Or it's turned up to deal with a regular .50 cal, but an AP round goes through. Or it's turned up all the way, and now you can't return fire, because cycling between protection and firing takes too long. Not to mention that dropping your shield to fire your own weapon also allows projectiles in.
There really isn't a practical way to prevent hull breaches from weapons that can pierce body armor. Unfortunately, there's just too many variables involved as well as too many forces to deal with to handle with anything, but magic or handwavium.