I have a 21' cobia glass boat with a 350 mercruiser. I have 2 36" bags that I use. I like to troll with the wind and most of the time I use both bags. but when the wind is light I only need 1 bag to get me down to speed. 2 bags just gives better boat control in rough water. and at times with both bags I do have to bump the throttle up just a little. but like said its easier to speed up just a little than to try to slow down.

and you do want trolling bags and not drift socks. you can use trolling bags for drifting but drift bags doesn't fair so well when trolling, I've used both.