[Grandpa Kim]

In my experience, boarding parties work quite well in the vanilla game. Against unshielded ships with no SDD, they are awesome. The best design, in fact, contains no weapons but the boarding party. Against shielded ships, shield depleters are the best weapon. Against the SDD... well, don't worry about the SDD. Either it won't be knocked out and you will not capture the ship, though contrary to what's been said, your boarding ships may still try to board thus destroying both ships-- a win for you, or your line ships will knock out the SDD and you will board successfully. You may get it virtually intact or you may get a gutted hulk. It's a crap shoot.

But the key it to have lots of boarding ships. Somewhere between 10% and 20% of each fleet should be boarding ships and you will make captures regularly.