Battery Size Recommendations?

I just got back from the lake and my trolling motor batteries finally went dead around 2:30pm this afternoon. I knew they would need replaced soon as I got 4+ excellent, trouble free years out them. They were AC Delco Voyager's 2 - M27MF, 1 - M24MF My question is are these batteries big enough for color electronics, a Mercury Optimax 225, Motorguide 767 Brute trolling motor 24v? I am considering a new trolling motor as well which might be 36v? Therefore do I need more power? Staying with the AC Delco Voyager line as they have been awfully good to me.
Feedback and opinions welcomed. Thanks in advance.

My philosophy is to always put the biggest possible batteries you can in. It's always better to have to much than not enough. more peace of mind as far as I'm concerned.

I just replaced mine with 29's

I bought a portable charging unit to keep in my boat as a backup, incase one of my batteries went dead on me. I fish a lot at night and since I have to keep my lights on while fishing according to the fish and game, to avoid a ticket. I am going to go to another battery for my boat as well. Just to add my fish sonar's to and nothing else. I have always been fond to the batteries from Wal-Mart..They have a very good warranty and if something goes bad with one, Wal-Mart is open 24-7 so I can get a replacement.

Now for Trolling motor, I have a Motorguide digital 70 on my boat...It has the Gator Mount and has all the power I need to push my Triton 196 on plane if need be.... Great Trolling motor in my honest opinion... it is a 24 volt system...

Now this info is just my own personal use, a lot of other members don't like Wal-Mart Batteries and prefer other types...But go with your best instincts and you'll do fine....

Gonna have to replace my cranking battery myself. At the moment I am running all Everstart 27's. And since I get my wife's discount at the Wally World plus their warranty, I will stay with the Everstart.
On this cranking baterry I may go to a 29, only if the battery box will allow it to fit. I don't want to change out the box if I can help it. I carry a 4th battery in the summer for night fishing, just to run my blacklights and spot light.