I just recently purchased an Optima Blue Top Battery to push my trolling motor, and I am not sure how to set my charger to charge the battery.  I have a charger with three settings for "charge rate" and three settings for "battery type":

Charge Rate: 2A, 10A, or 15A

Battery Type: Regular, Deep Cycle, or AGM Gel Cell

I'm assuming it would be best to set the charge rate @ 2A, because I've been told the slower charge will preserve battery life.  But, I don't know if the Optima Blue Top would be considered a 'regular,' 'deep cycle,' or 'AGM Gel Cell' type of battery.  

Any help/explanation on this would be greatly appreciated.

P.S.  Here is a link to the Optima Batteries website.  I have a model D27M:

https://www.optimabatteries.com/products/bluetop

Optima blue top batters are AGM cell (sprial) style batteries.  As far as your amperage goes, I am not exactly sure on the AGMs.... the others are completely fine to do 15 amps on.  Your battery should say somewhere I would think, if not on their site.  I really dont think it matters too much... the more amps the faster your charge. The main thing is you would want to be sure to turn it off when fully charged or make sure your charger has a "float" mode where it wont overcharge it.  

10 amp, AGM Mode.  

NEVER use the 2 amp mode on anything but your lawn and garden size batteries.

On an AGM, it's not quite so critical not to use the 2 amp mode, but on the standard flooded cell battery, you could never fully charge a full size group 24/27 etc. it in the 2 amp mode

AGM batteries are NOT Gel batteries and require different charging cycles than wet lead acid and AGM's.  A lot of people get the AGM and Gel batteries confused.

With a marine battery, the general rule of thumb is to charge it at 10% of the amp hour rating of the battery. For example, 100 amp hour battery should be charged at 10 amps. Always charge the battery no more than 24 hours after using it and try not to discharge it more than 50%. The shallower the discharge, the longer the battery will last. Here is a list of battery groups and the approximate amps which they should be charged.  

12V U1 4.5 Amps

12V Group 22NF  6.0 Amps

12V Group 24 8.0 Amps

12V Group 27 10.5 Amps

12V Group 31 13.5 Amps

thank y'all for the great info!

I have Optima batteries on my boat and my old battery charger was not charging fully I talked to the Optima rep for my area and he recommended a Professional Mariner Charger I switched to one and have not had any problems since. They are a little pricey I got mine at the spring sale at BPS for 249 but they are regularly about 300.