2d shows a "cartoon like" image of stuff under the boat...
DI shows a "picture like" image of stuff under the boat...and out to the sides a few feet...
SI shows a "picture like" image of stuff under the boat, out to the sides 100+ ft...and which side of the boat...

SI advantage is finding structure....then re-position the boat to effectly fish that "new-found structure" with the DI or the 2d...

Rickie