In Eve, there are three mining barges. The Covetor clearly holds the distinction of having the highest mining yield for group operations, however I am more interested in the comparison between the highly defensible Procurer for low-sec mining and the Retriever for high-sec AFK mining.
Do these two barges have the same mining yield?
On the surface it seems so, the Procurer only has one turret but it has a 66% cycle reduction in Ice mining and a 200% yield on strip while the Retriever has two turrets, each doing 50% more yield and 33% less cycle on ice. However, when you factor in skills, mining crystals and other equipment that increases yield (or decreases ice cycle time), does one barge outmine the other?
Best Answer
These mining barges serve different purposes.
The Procurer is massively more durable than the retriever. It has far more armor, shield, etc (and a Mining Barge skill bonus to shields) which make it idea for situations where defense might matter (suicide ganks in high sec, wormhole mining, etc).
The retriever is very flimsy, but has double the ore-hold, reducing the number of trips back to station.
From a yield perspective, looking at regular mining, they are basically the same:
Where X is 1 normal strip miner: Procurer: 1 turret @ 300% = 3X Retriever: 2 turrets @ 150% = 3X The retriever has 1 extra low slot, which might increase the yield slightly through mining upgrades.
Effective Hit Points (EHP): Procurer: 5500 + 5000 + (6000 * 1.25) = 18000 (also 4 med slots = much greater shield tank) Retriever: 2000 + 1700 + 2300 = 6000 (with only 1 mid slot!)
Cargo: Retriever: 22000 * 1.25 = 27500 m3 Procurer: 12000 m3
I think the above summarizes the tradeoffs. The mining yeild is very similar - but defense vs cargo space is really the decision making factor.