You can keep them from rolling up in a ball by keeping them on ice and/or by stunning them, hold them by the head and whack the last 1/3rd of the the reel agains someting solid. I was going to say a rock but you'll have difficulty finding one on the boat
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You can 3 way them to get them down deep or depending on the depths you are fishing go weightless, weighted sliding egg, or rubber core... If on a boat I prefer to cast them to structure...