First a couple of explanations. All of the math that Cryptic uses for most of the game uses the basic form of BASE x [or / ] ( 1 + (buff1 + buff2 ... + buffN) / 100 ) ). Where buff# is a source of skill increase (i.e captain skills, ability affect, gear, etc). That form of math has a diminishing return or (or a curve which flattens out as your increase the buff# total.

So if you have a BuffN sum of say 150. Adding +20 won't increase your net value by that much. (20 x (1 + (150 / 100)) = 20 x (1 + 1.5) = 50. 20 x (1 + ( 150 + 20)/100)) = 20 x ( 1 +1.7 ) = 54 (which is a net increase of +4).

That is why weapon consoles do add as much as you would thing. The weapon damage foumula is as follows (via Geko in an interview).

Base weapon damage x ( 1 + <weapon-mk-modifier> + <ship-tier-modifier> + <weapon-training-skill>/100 + <X-weapons-skill>/100 + <consoles-total> / 100) + 0.015 x <# non-dmg-attribs> + 0.075*<# of DMG attribs).

The weapon MK and Ship Tier modifiers start at 0 and go up (MK X weapon is 1.0 and Tier 5 Ship mod is 1.0). (The above is from memory. The numbers may be off. )

And hull damage resistance uses a different, more complicated formula. See

http://www.stowiki.org/Damage_resistance . The curve is one that approaches 75% by never reaches it.