For whatever reason you've decided boarding another ship is required. The other ship's crew is not keen on the idea. What can a crew of merchants do to stop you? Quite a bit if the captain has half a brain; and they don't give masters papers to people with less than a whole brain!
Boarding actions require getting close to your target ship. Usually that requires you need to disable its drives. The power plant is the best target because once it is shut down the target ship enters a powered down state. The technical term for this is 'screwed.' Otherwise both the maneuver and jump drives have to be taken offline. A ship that jumps out of system with your boarding party is a little inconvenient.
I recommend a Select program for those trying to disable a ship. Having a person onboard the ship can also be very handy. A pilot can find it hard to maneuver with a body pistol against his head.
A ship that is brought to maneuver-0 can't maneuver in the normal scheme of things. It may still have working thrusters and gyros for docking and such. A ship that can move a couple of meters a second can make a mess of another ship close by. Of course your captain may say to hell with this and keep station a few hundred meters or a couple of klicks away.
Some ships have boarding tubes: flexible extensions with an airlock on the end to latch onto a target's hull and begin cutting a hole through the hull using saws or lasers. The tube is sturdy enough not to be damaged by less than a gee of acceleration. Many ships don't have these. Unless you run a salvage operation they scream PIRATE for one thing. Another way to get over is to use a launch or boat to avoid damaging the main ship. This might be hard on the boarding party and the launch.
Boarding parties may also use vacc suits and go EVA to get to the other ship. They can use grapple guns or rocket thrusters depending on how close the ships are.
A few militaries use boarding capsules (no stats, I'm making this up.) A boarding capsule is like a closed boarding tube with rocket thrusters at one end and a bunch of restraints for some troops. The attacking ship launches a capsule, it slams into the target and cuts a way in.
While I'm on this topic a ship is dangerous in far more ways than just squashing your launch or throwing a boarding party into space with random jerks. You have active sensors and communications transmitters . Those things reach across millions of klicks and can cook you right in your space suit. A ship might generate heat and radiation around it when under full power. Remember designers only have to worry about shielding the main compartment which is on the inside of the hull. A distributed structure hull might fill the space around it with radiation when its power plant is running and for a few hours afterwards. The crew might feel killing your future offspring is not deterrent enough and also pump whatever corrosive chemicals they can spare into the void creating a gas cloud that will eat your space suit,
Finally that unarmed trader may turn out to have a heavy machine gun or VRF gauss cannon in its otherwise empty turret. useless for starship combat but fine to put holes in a launch a few hundred meters off or raise merry hell with some idiots in vacc suits. Really paranoid captains may attach fragmentation devices to the hull on armored plates. Hand grenades hate vacc suits and their wearers.
My next post will cover the antics once you get to the ship you want so badly.