I have seen several players in discussion about the very high level of scuttle damage applied when a drifting hulk explodes, and how this is unduly punishing for fleets that rely heavily on boarding like Space Marines and Tyranids, and at the same time I have seen other players talking about how boarding and other assault attacks, especially from Tyranids, can extremely quickly wipe out the crew of even a battleship and leave it drifting. Both sides of this debate feel the situiation is unfair, and I have seen for myself that both sides have a point, and after some thought I have lit upon what I think might be a solution.
I would suggest that all capital ships (escorts have crews too small to effectively fight off a concerted boarding action from a larger ship) should get access to a dedicated 'repel boarders' stance, which reflects the general crew being armed and rushed to improvised barricades, bulkheads being locked down, power being diverted to internal defence networks and force fields, and similar such measures.
The effect in game might be a reduced risk of suffering critical damage from assault boats, lightning strikes, boarding actions and other assault options like Lictor Infestations, along with increased resistance to troop losses caused by such attacks. Using the stance would also have negative effects, possibly reducing fire rate, ship manouverability and the cooldown rate of ship abilities while in the stance, since the crew are at the barricades and armed to fight boarders instead of being at their posts, making using the stance a trade off for the player.
At the same time, since boarding is less of an overwhelming threat in all instances with such a stance available, scuttle damage could be reduced to a more reasonable level, perhaps something like 100 damage to all ships within its area of effect absorbed by shields, or possibly the chance of successfully scuttling the ship is not certain, with the greater the forces committed to the boarding of a ship by an attacker, the lesser the odds that it can be successfully scuttled before the crew are all killed, making borading a real all or nothing manoeuver.
I would further suggest that recrewing a ship with a skeleton crew should also carry greater penalties (the original crew being all dead and the replacement crew being heavily understrength and not familiar with the ship). Reduced fire rate is a good start, but I would also say that the recrewed ship can no longer perform assault actions of any kind of its own (it has too few personnel aboard to attempt such a feat) and all ability cooldowns should be extended by 50% for the remainder of the battle. That seems like a reasonable consequence for the loss of an entire ship's crew strength.