I have never used underspins and I hope you will give me an education;  I do have a sizeable assortment of them, unused.  Lets say I'm in 40 feet of semi clear water, 55 degrees, no grass, tons of shad balls near the bottom.  What is your retrieval method and choice of trailers?

Kinda deep for an underspin IMO.

 

I'd throw a DropSwim in that situation.

My underspin success definitely leans toward small baits.  2.8" keitech was a mainstay, but this year I've done much better with a 3" armor shad straight tail.  I really like the northland tackle smeltinator underspin in 1/2oz 1/0.  I've never been on fish in 40', but 25-30' fow crawling on the bottom or slow rolling mid column is my cold water success.

 

scott

I fish underspins a LOT, but never that deep. I'm not patient enough to let them sink that far and will normally choose something with a much heavier weight/bulk ratio for a quicker sink. 

 

For me, underspins are a go-to technique in like 12' of water or less. If you ever have questions about their use in that scenario, I'd be happy to talk. 

For the 40ft situation mentioned.  Heavier head and roll on the bottom

3 hours ago, webertime said:

For the 40ft situation mentioned.  Heavier head and roll on the bottom

I did that today but no bites;  all bites came from strolling.