24v battery charging question?

[mlovelace]

I just installed a 24v trolling motor. I have 2. 12v batteries that are deep cycle. I just purchased a charger and noticed it stated I need to take the batteries out to charge? It stated to leave in the boat, I would need special equipment? Just curious to if you leave your battery in the boat and bring a charger to it or do you take your batteries out? Also, what is it meaning you can leave in and charge with special equipment. I am using a portable charger Schumacher...ship to shore.

THank you, Mike