Hey fellas there are several variables that go into bag selectionsuch as boat size, engine hp, and time of year you do most of your trolling. For me I run 54" bags in the early spring to early summer, mid to late summer I can run 36" bags. Rule of thumb its easier to speed up than to slow down. Yes you will burn a bit more fuel, but you keep more control too.

Rough sizing
18-23 foot boats can usually get away with 30-36" bags
24-26 36"-48"
27-30 48"-54"

These are just rough numbers put ya close like I said depends on hp and speeds your looking for. We usually sell the bags and if your need to adjust size up or down bring it back pay the difference or well give you the difference back as long as they aren't damaged your good to go. These bags are tough never had any issues with them being swapped out like skipper 9 said 7 yrs no joke. Feel free to call stop in or pm me.