The key to win melee batlles is so damn simple, that it totally ruins it.
Do as follow:
- In every of your ships put the highes lvl Security Room you can get.
- Reassign 2 of your crew with the highest combat values to security (only for this battle)
As long as your attack value is a lot higher than that of your enemy, it's very hard to loose.
If your attack value is lower than that of your enemy it is very hard to win ever!