Right now boarding feels weird, one second your ship has full crew the next one you have a drifting hulk which hurts balance and makes 0 sense on lore so i thought on some changes.

  1. Make boarding a damage over time effect rather than instant
    This has been mentioned in other posts already so yeah why not lets say x ship deals 12 boarding damage make it 4 every 3 seconds that will give time for the boarded oponent to react

  2. Increase ship troops

  3. make it that every time a tick happens there is a chance the ship can suffer a critical strike

Basically this would represent the boarders dealing damage to critical parts of the ship maybe to make it balanced make that only 1 or 2 effects can happen max and maybe 3 for space marines.

  1. Make it too that every time a tick happens the boarding action can be cancelled or halved.

This chance could be based on ship tonnage ,on the number of troops and some factions could get an extra % on ship protection against boarding crits like tyranids since boarding a tyranid ship will probably be a terrible idea, this also means that some skills or upgrade could be directed toward this( meaning that boarding a fully crewed ship will be harder than crewing a ship thats close to ecome a drifting hulk).