I got a brand new Westmarine trolling battery and I hooked it up to my charger to top it off. The charger ran for about 3 hrs at 6 amps and the meter on the charger still didn't read "full". I have a three stage "smart" charger that is supposed to start at 6 amps, then drop down to 4 amps and then 2 amps until the charge is full. My charger stayed at 6 amps for three hours and then I just unhooked it. Do you have to charge a brand new battery or is it on full charge right out of the store?

That all depends on just how "new" it is. Sometimes batteries set around for several months before they are sold and need a good charging. If you own a hydrometer, check the cells with it.  If you don't own one, plug it back in and give it some more time and buy a hydrometer.

Every battery I ever bought was from sears and they test it before it leaves the store.  It should be charged when you bring it home.

Most likely you probably just haven't charged the battery enough.  Gotta realizie, a 6 amp charger for 3 hours, that's only 18 amps.  even if that's only a group 24 and 105 Ah, if the battery was at 75%, that would not have been enough to charge it to 100%.  When you buy a battery, no telling how long it has set on the shelf.  I've seen a lot of batteries at 50% off the shelf.  Actaully, I've seen junk batteries sold because they sat on shelf for almost a year without ever having a sevrice charge put on them.  

If you want have fun, check out the manufactor date.  This is a date code etched into the battery, usually around the side near the top.  This is not the same as the delivery date sticker or burned into the battery, that has nothing to do with the date it was made, the could be months and months difference between the two.